Chapter 17 PEDIATRIC ENDODONTICS

Transcription

1 Chapter 17 PEDIATRIC ENDODONTICS Clifton O. Dummett Jr and Hugh M. Kopel Treatment of pulpally inflamed primary and permanent teeth in children presents a unique challenge to the dental clinician. Pulp diagnosis in the child is imprecise as clinical symptoms do not correlate well with histologic pulpal status. Age and behavior can compromise the reliability of pain as an indicator of the extent of pulp inflammation. Furthermore, treatment goals are developmentally oriented and may be relatively short term by comparison to the long-term restorative permanence of adult endodontics. Because of this latter fact, a major focus in pediatric pulp therapy is vital pulp treatment, that capitalizes on the healing potential of the noninflamed remaining portions of the pulp. With instances of irreversibly inflamed and necrotic radicular pulps, conventional concepts of nonvital pulp treatment are indicated. However, they must be modified to accommodate physiologic root resorption in primary teeth and continued root development in young permanent teeth. Lewis and Law succinctly stated the ultimate objective of pediatric pulp therapy: The successful treatment of the pulpally involved tooth is to retain that tooth in a healthy condition so it may fulfill its role as a useful component of the primary and young permanent dentition. 1 Premature loss of primary teeth from dental caries and infection may result in the following sequelae: Loss of arch length Insufficient space for erupting permanent teeth Ectopic eruption and impaction of premolars Mesial tipping of molar teeth adjacent to primary molar loss Extrusion of opposing permanent teeth Shift of the midline with a possibility of crossbite occlusion Development of certain abnormal tongue positions It is for this reason that maximum attempts must be made to preserve primary teeth in a healthy state until normal exfoliation occurs. A major contention in contemporary research involving vital pulp treatment is the definition of healthy pulp status ascribed to many of the treatment outcomes. This issue will be addressed in more detail later in this chapter. Vital pulp therapy is based on the premise that pulp tissue has the capacity to heal. In addition to the biologic basis for the healing capacity of the pulp, differences between primary and permanent teeth exist from a morphologic and histologic standpoint. These differences must be addressed by the clinician to successfully treat pulpally inflamed teeth in children. PULP MORPHOLOGY Anatomic Differences Between Primary and Permanent Teeth Anatomic differences between the pulp chambers and root canals of primary teeth and those of young permanent teeth have been described 2 (Figure 17-1): (1) Pulp chamber anatomy in primary teeth approximates the surface shape of the crown more closely than in permanent teeth. (2) The pulps of primary teeth are proportionately larger and the pulp horns extend closer to the outer surfaces of the cusps than in permanent teeth. (3) The pulp-protecting dentin thickness between the pulp chamber and the dentinoenamel junction is less than in permanent teeth. These three factors increase the potential for pulp exposure from mechanical preparation, dental caries, and trauma. (4) An increased number of accessory canals and foramina, as well as porosity in pulpal floors of primary teeth, has been noted in comparison with permanent teeth. 3 This is thought to account for the consistent pulp necrosis response of furcation radiolucency in primary teeth versus periapical radiolucency in permanent teeth. 4 6

2 862 Endodontics Figure 17-1 Comparative anatomy between primary (left) and permanent (right) molars. Primary teeth are smaller in all dimensions; their enamel cap is thinner, with less tooth structure protecting the pulp. Primary pulp horns are higher, particularly mesial. The roots of primary molars are longer and more slender, are pinched in at the cervical part of the tooth, and flare more toward the apex to accommodate permanent tooth buds. All of these factors tend to increase the incidence of pulp involvement from caries or complicate canal preparation and obturation. Reproduced with permission from Finn SB. 2 A comparison of root canals in primary teeth with those of young permanent teeth reveals the following characteristics: (1) the roots of primary teeth are proportionately longer and more slender; (2) primary root canals are more ribbon-like and have multiple pulp filaments within their more numerous accessory canals; (3) the roots of primary molars flare outward from the cervical part of the tooth to a greater degree than permanent teeth and continue to flare apically to accommodate the underlying succedaneous tooth follicle; (4) the roots of primary anterior teeth are narrower mesiodistally than permanent anterior tooth roots; and (5) in contrast to permanent teeth, the roots of primary teeth undergo physiologic root resorption. These factors make complete extirpation of pulp remnants almost impossible and increase the potential of root perforation during canal instrumentation. As a result, the requirements of primary root canal filling materials must encompass germicidal action, good obturation, and resorptive capability. 3 Histologic Considerations Numerous descriptions of pulp histology exist that identify the various cell components of pulp tissue. 7,8 Consistently, the pulp is primarily connective tissue and has considerable healing potential. Features that distinguish pulp tissue from other connective tissue include the presence of odontoblasts, absence of histamine-releasing mast cells, tissue confinement in a hard cavity with little collateral circulation, and vascular access limited to the root apex. 7,8 Pulp healing capability is affected by endogenous factors of coronal cellularity and apical vascularity. Both are increased in primary and young permanent teeth. 8 Pulps become more fibrous, less cellular, and less vascular with age. 8 Exogenous factors affecting pulp healing include bacterial invasion and chemical/thermal insult. Current research in pulp biology and restorative materials strongly substantiates the need for bacterial microleakage control in maximizing pulp survival. 9 Fox and Heeley concluded that, histologically, no structural differences exist between primary pulp tissue and young permanent pulp tissue with the exception of the presence of a cap-like zone of reticular and collagenous fibers in the primary coronal pulp. 10 However, many clinicians have noted different pulp responses between primary and young permanent teeth to trauma, bacterial invasion, irritation, and medication. Anatomic differences may contribute to these responses. Primary roots have an enlarged apical foramen, in contrast to the foramen of permanent roots, which is constricted. The resultant reduced blood supply in mature permanent teeth favors a calcific response and healing by calcific scarring. 11 This hypothesis is exemplified in older pulps, in which more calcified nodules and ground substance are found than in young pulps. Primary teeth, with their abundant blood supply, demonstrate a more typical inflammatory response than that seen in mature permanent teeth. The exaggerated inflammatory response in primary teeth may account for increased internal and external root resorption from calcium hydroxide pulpotomies. The alkalinity of calcium hydroxide can produce severe pulp inflammation and subsequent metaplasia with resultant internal primary root resorption. It has been shown that the greater the inflammation, the more severe the resorption (Figure 17-2). Although it is suspected that pulps of primary teeth have a different function from those of permanent teeth, no supporting data are available. Some clinicians believe that primary teeth are less sensitive to pain than permanent teeth, probably because of differences in the number and/or distribution of neural elements. When comparing primary and permanent teeth, Bernick found differences in the final distribution of pulp nerve fibers. 12 In permanent teeth, these fibers terminate mainly among the odontoblasts and even beyond the predentin. In primary teeth, pulp

3 Pediatric Endodontics 863 A B Figure 17-2 Internal resorption triggered by inflammation. A, Advanced caries in a 5-year-old child. Note calcification (arrow) in the first primary molar (contraindication for pulp therapy). B, Same patient 6 months later. Marked internal resorption, forecast in the earlier radiograph, indicates advanced degenerative changes. Reproduced with permission from Law DB, Lewis TM, Davis JM. An atlas of pedodontics. Philadelphia: WB Saunders; nerve fibers pass to the odontoblastic area, where they terminate as free nerve endings. Bernick postulated that if primary teeth were not so short-lived in the oral cavity, their nerve endings might terminate among the odontoblasts and in the predentin as in permanent teeth 12 (Figure 17-3). Rapp and associates concurred with Bernick s hypothesis and also stated that the density of the innervation of the primary tooth is not as great as that of the permanent tooth and may be the reason why primary teeth are less sensitive to operative procedures. 13 They agree, however, that as the primary teeth resorb, there is a degeneration of the neural elements as with other pulp cells. Neural tissue is the first to degenerate when root resorption begins, just as it is the last tissue to mature when the pulp develops. Primary and permanent teeth also differ in their cellular responses to irritation, trauma, and medication. It has been shown, for example, that the incidence of reparative dentin formation beneath carious lesions is Figure 17-3 Section of pulp from a human primary molar. Note that the majority of nerves terminate at the pulp-odontoblastic (PO) border. Only isolated nerve fiber penetrates the P-O border to terminate in the zone of Weil. D = dentin; N = nerve fiber; O = odontoblasts; Pr = predentin; PO = pulp-odontoblast border. Reproduced with permission from Bernick S. 12 more extensive in primary than in permanent teeth McDonald reported that the localization of infection and inflammation is poorer in the primary pulp than in the pulp of permanent teeth. 18 MANAGEMENT OF DEEP CARIOUS LESIONS AND PULP INFLAMMATION IN PRIMARY AND YOUNG PERMANENT TEETH Pulp therapy for primary and young permanent teeth has historically been subject to change and controversy. Pulp medicaments, such as zinc oxide eugenol (ZOE) cement, calcium hydroxide, and formocresol, have been the basis for much of this controversy. A better understanding of the reactions of the pulp and dentin to these medicaments has developed over time, primarily through improvements in histologic techniques. Anderson and colleagues felt that the pulp and dentin should be considered as one organ. 19 Frankl determined that this pulpodentinal system reaction is proportional to the intensity and duration of the offending agents of caries, trauma, medicaments, or restorative materials. 20 A correct diagnosis of pulp conditions in primary teeth is important for treatment planning. McDonald and Avery have outlined several diagnostic aids in select-

4 864 Endodontics ing teeth for vital pulp therapy. 3 Eidelman et al. 21 and Prophet and Miller 22 have emphasized that no single diagnostic means can be relied on for determining a diagnosis of pulp conditions. Rayner and Southam have stated that the inflammation response to the effects of dentin caries in the deciduous pulp is more rapid than in the permanent pulp. 23 Yet Taylor concluded that in spite of being inflamed and infected by the carious process, primary molars are still capable of marked defense reactions similar to those observed in permanent teeth. 24 The goal in managing the deep carious lesion is preservation of pulp vitality before arbitrarily instituting endodontic therapy. A suggested outline for determining the pulpal status of cariously involved teeth in children involves the following: 1. Visual and tactile examination of carious dentin and associated periodontium 2. Radiographic examination of a. periradicular and furcation areas b. pulp canals c. periodontal space d. developing succedaneous teeth 3. History of spontaneous unprovoked pain 4. Pain from percussion 5. Pain from mastication 6. Degree of mobility 7. Palpation of surrounding soft tissues 8. Size, appearance, and amount of hemorrhage associated with pulp exposures dentin, after deep excavation, with no exposure of the pulp. In 1961, Damele described the purpose of indirect pulp capping as the use of reconstructed dentin to prevent pulp exposure. 25 The treatment objective is to avoid pulp exposure and the necessity of more invasive measures of pulp therapy by stimulating the pulp to generate reparative dentin beneath the carious lesion. This results in the arrest of caries progression and preservation of the vitality of the nonexposed pulp. 26 This technique can be used as a one-sitting procedure or the more classic two-sitting procedure. The latter involves re-entry after a 6 to 8-week interval to remove any remaining carious dentin and place the final restoration 3,27 (Figure 17-4). DiMaggio found, in a histologic evaluation of teeth selected for indirect treatment, that 75% would have been pulp exposures if all of the caries had initially been removed. Using clinical criteria, this same study showed a failure rate of only 1% for indirect pulp caps compared with 25% failure for direct caps. 28 A histologic examination, however, raised these failure rates to 12% and 33%, respectively. Trowbridge and Berger stated that complete removal of softened dentin, with ensuing pulp exposure, may contribute nothing of diagnostic value in estimating the extent of existing pulp disease. 29 In fact, other studies have shown that the true picture of pulp disease cannot be assessed on the basis of such diagnostic criteria as history of pain, response to temperature change, percussion, and electric pulp testing. 30,31 Pediatric pulp therapy for primary and young permanent teeth involves the following techniques: 1. Indirect pulp capping 2. Direct pulp capping 3. Coronal pulpotomy 4. Pulpectomy The first three methods are vital techniques that involve conservative management of portions of inflamed pulp tissue with the preservation of the remaining vital pulp. The pulpectomy procedure is a nonvital technique and involves the complete extirpation of the irreversibly inflamed and/or necrotic pulp followed by canal obturation with a resorbable medicament in primary teeth and conventional root canal filling in permanent teeth. INDIRECT PULP CAPPING Indirect pulp capping is defined as the application of a medicament over a thin layer of remaining carious Figure 17-4 Indirect pulp-capping technique. A, Medicament, either zinc oxide eugenol cement, calcium hydroxide, or both, against remaining caries. B, Lasting temporary restoration. Following repair, both materials are removed along with softened caries, and final restorations are placed.

5 Pediatric Endodontics 865 Historical Review The concept of indirect pulp capping was first described by Pierre Fauchard as reported by John Tomes in the mid-18th century, who recommended that all caries should not be removed in deep, sensitive cavities for fear of exposing the nerve and making the cure worse than the disease. 32 John Tomes, in his mid- 19th century textbook, stated, It is better that a layer of discolored dentin should be allowed to remain for the protection of the pulp rather than run the risk of sacrificing the tooth. 32 Although neither of these dental pioneers referred to any specific medication for the softened dentin, they recognized the healing capacity of the pulp. In 1891, W. D. Miller discussed various antiseptics that should be used for sterilizing dentin. 34 In contrast to these early reports advocating conservative management of deep lesions, G. V. Black felt that in the interest of scientific dental practice, no decayed or softened material should be left in a cavity preparation, whether or not the pulp was exposed. 35 Rationale Indirect pulp capping is based on the knowledge that decalcification of the dentin precedes bacterial invasion within the dentin This technique is predicated on removing the outer layers of the carious dentin, that contain the majority of the microorganisms, reducing the continued demineralization of the deeper dentin layers from bacterial toxins, and sealing the lesion to allow the pulp to generate reparative dentin. Fusayama and colleagues demonstrated that in acute caries, dentin discoloration occurred far in advance of the microorganisms, and as much as 2 mm of softened or discolored dentin was not infected. 38 In a later study, Fusayama found that carious dentin actually consists of two distinct layers having different ultramicroscopic and chemical structures. 39 The outer carious layer is irreversibly denatured, infected, and incapable of being remineralized and should be removed. The inner carious layer is reversibly denatured, not infected, and capable of being remineralized and should be preserved. The two layers can be differentiated clinically by a solution of basic fuchsin. 39 Whitehead and colleagues compared deep excavations in primary and permanent teeth. 40 After all softened dentin had been removed from the cavity floor, they found that 51.5% of the permanent teeth were free from all signs of organisms, and a further 34% had only 1 to 20 infected dentinal tubules in any one section. 40 Primary teeth, however, showed a much higher percentage of bacteria in the cavity floor after all softened dentin was removed. These results were further supported by Shovelton, who found that although the deepest demineralized layers of dentin were generally free from infection, the possibility of a few dentinal tubules containing organisms did exist, especially in primary teeth. 41 This finding was supported by Seltzer and Bender. 42 Thus, complete clinical removal of carious dentin does not necessarily ensure that all infected tubules have been eradicated. Conversely, the presence of softened dentin does not necessarily indicate infection. A number of investigators have provided evidence that the pulp can readily cope with minute contamination. Reeves and Stanley 43 and Shovelton 44 showed that when the carious lesion proximity to the pulp was greater than 0.8 mm (including reparative dentin when present), no significant disturbance occurred within the pulp of permanent teeth. Rayner and Southam, in studying carious primary teeth, found the mean depth of pulp inflammatory changes from bacterial dentin penetration to be 0.6 mm in proximity to the pulp, with some changes occurring within a 1.8 mm pulp proximity. 23 Massler considered that pulp reactions under deep carious lesions result from bacterial toxins rather than the bacteria themselves. 45 Massler and Pawlak used the terms affected and infected to describe pulp reaction to deep carious attack. 46 This histologic study showed that the affected pulp, beneath a deep carious lesion with a thin layer of dentin between the pulp and the bacterial front, was often inflamed and painful but contained no demonstrable bacteria. However, when significant numbers of bacteria were found within the infected pulp, a microscopic exposure in the carious dentin was seen. Canby and Bernier concluded that the deeper layers of carious dentin tend to impede the bacterial invasion of the pulp because of the acid nature of the affected dentin. 47 The results of these studies indicate the presence of three dentinal layers in a carious lesion: (1) a necrotic, soft, brown dentin outer layer, teeming with bacteria and not painful to remove; (2) a firmer, discolored dentin layer with fewer bacteria but painful to remove, suggesting the presence of viable odontoblastic extensions from the pulp; and (3) a hard, discolored dentin deep layer with a minimal amount of bacterial invasion that is painful to instrumentation. Response to Treatment Sayegh found three distinct types of new dentin in response to indirect pulp capping: (1) cellular fibrillar dentin at 2 months post-treatment, (2) presence of

6 866 Endodontics globular dentin during the first 3 months, and (3) tubular dentin in a more uniformly mineralized pattern. 17 In this study of 30 primary and permanent teeth, Sayegh concluded that new dentin forms fastest in teeth with the thinnest dentin remaining after cavity preparation. He also found that the longer treatment times enhanced dentin formation. 17 Diagnosis of the type of caries influences the treatment planning for indirect pulp capping. In the active lesion, most of the caries-related organisms are found in the outer layers of decay, whereas the deeper decalcified layers are fairly free of bacteria. In the arrested lesion, the surface layers are not always contaminated, especially where the surface is hard and leathery. The deepest layers are quite sclerotic and free of microorganisms. 48 Deep carious dentin is even more resistant to decomposition by acids and proteolysis than is normal dentin. This was especially true in arrested caries. 49,50 Procedures for Indirect Pulp Capping Case selection based on clinical and radiographic assessment to substantiate the health of the pulp is critical for success. Only those teeth free from irreversible signs and symptoms should be considered for indirect pulp capping. The following measures should be employed for those teeth appropriate for this technique. Indications. The decision to undertake the indirect pulp capping procedure should be based on the following findings: 1. History a. Mild discomfort from chemical and thermal stimuli b. Absence of spontaneous pain 2. Clinical examination a. Large carious lesion b. Absence of lymphadenopathy c. Normal appearance of adjacent gingiva d. Normal color of tooth 3. Radiographic examination a. Large carious lesion in close proximity to the pulp b. Normal lamina dura c. Normal periodontal ligament space d. No interradicular or periapical radiolucency Contraindications. Findings that contraindicate this procedure are listed below: 1. History a. Sharp, penetrating pain that persists after withdrawing stimulus b. Prolonged spontaneous pain, particularly at night 2. Clinical examination a. Excessive tooth mobility b. Parulis in the gingiva approximating the roots of the tooth c. Tooth discoloration d. Nonresponsiveness to pulp testing techniques 3. Radiographic examination a. Large carious lesion with apparent pulp exposure b. Interrupted or broken lamina dura c. Widened periodontal ligament space d. Radiolucency at the root apices or furcation areas If the indications are appropriate for indirect pulp capping, such treatment may be performed as a twoappointment or a one-appointment procedure. Two-Appointment Technique (First Sitting). 1. Administer local anesthesia and isolate with a rubber dam. 2. Establish cavity outline with a high-speed handpiece. 3. Remove the majority of soft, necrotic, infected dentin with a large round bur in a slow-speed handpiece without exposing the pulp. 4. Remove peripheral carious dentin with sharp spoon excavators. Irrigate the cavity and dry with cotton pellets. 5. Cover the remaining affected dentin with a hard-setting calcium hydroxide dressing. 6. Fill or base the remainder of the cavity with a reinforced ZOE cement (IRM Dentsply-Caulk; Milford.) or a glass-ionomer cement to achieve a good seal. 7. Do not disturb this sealed cavity for 6 to 8 weeks. It may be necessary to use amalgam, composite resin, or a stainless steel crown as a final restoration to maintain this seal. Two-Appointment Technique (Second Sitting, 6 to 8 Weeks Later). If the tooth has been asymptomatic, the surrounding soft tissues are free from swelling, and the temporary filling is intact, the second step can be performed: 1. Bitewing radiographs of the treated tooth should be assessed for the presence of reparative dentin. 2. Again use local anesthesia and rubber dam isolation. 3. Carefully remove all temporary filling material, especially the calcium hydroxide dressing over the deep portions of the cavity floor. 4. The remaining affected carious dentin should appear dehydrated and flaky and should be easily removed. The area around the potential exposure

7 Pediatric Endodontics 867 should appear whitish and may be soft; this is predentin. Do not disturb! 5. The cavity preparation should be irrigated and gently dried. 6. Cover the entire floor with a hard-setting calcium hydroxide dressing. 7. A base should be placed with a reinforced ZOE or glass ionomer cement, and the tooth should receive a final restoration. One-Appointment Technique. The value of re-entry and re-excavation has been questioned by some clinicians when viewed in light of numerous studies reporting success rates of indirect pulp capping with calcium hydroxide ranging from 73 to 98% (Table 17-1). On this basis, the need to uncover the residual dentin to remove dehydrated dentin and view the sclerotic changes has been questioned. The second entry subjects the pulp to potential risk of exposure owing to overzealous re-excavation. 7 Leung et al. 51 and Fairbourn and colleagues 52 have been able to show a significant decrease of bacteria in deep carious lesions after being covered with calcium hydroxide (Dycal, Dentsply-Caulk; Milford.) or a modified ZOE (IRM) for periods ranging from 1 to 15 months. These investigators suggested that re-entry to remove the residual minimal carious dentin after capping with calcium hydroxide may not be necessary if the final restoration maintains a seal and the tooth is asymptomatic. After cavity preparation, if all carious dentin was removed except the portion that would expose the pulp, re-entry might be unnecessary. 7 Conversely, if the clinician had to leave considerably more carious dentin owing to patient symptoms, re-entry would be advised to confirm reparative dentin and pulp exposure status. If a pulp exposure occurs during re-entry, a more invasive vital pulp therapy technique such as direct pulp capping or pulpotomy would be indicated. Tooth selection for one-appointment indirect pulp capping must be based on clinical judgment and experience with many cases in addition to the previously mentioned criteria. Evaluation of Therapy. A histologic evaluation of pulp reactions to indirect pulp capping has been reported in a varying number of samples. Law and Lewis reported irritational dentin formation, an active odontoblastic layer, an intact zone of Weil, and a slightly hyperactive pulp with the presence of some inflammatory cells. 53 Held-Wydler demonstrated irritational dentin in 40 of 41 young molars in which the carious dentin was covered with ZOE cement. 54 The pulp tissue was either completely normal or mildly inflamed over a period of Table 17-1 Studies on Indirect Pulp Capping in Primary and Young Permanent Teeth Study Agent Cases Observation Period % of Success Sowden, 1956 Ca(OH) 2 4,000 Up to 7 y Very high Law and Lewis, 1961 Ca(OH) 2 38 Up to 2 y 73.6 Hawes and DiMaggio, 1964 Ca(OH) Up to 4 y 97 Kerkhove et al., 1964 Ca(OH) mo 95 ZOE mo 95 Held-Wydler, 1964 Ca(OH) d 88 King et al., 1965 Ca(OH) d 62 ZOE Aponte, 1966 Ca(OH) mo 93 Jordan and Suzuki, 1971 Ca(OH) wk 98 Nordstrom et al., 1974 Ca(OH) d 84 SnFl 90 Magnusson, 1977 Ca(OH) Sawusch, 1982 Ca(OH) mo 97 Nirschl and Avery, 1983 Ca(OH) mo 94 Coll, 1988 Ca(OH) mo 92.3 Ca(OH) 2 = calcium hydroxide; ZOE = zinc oxide eugenol; SnFI = stannous fluoride.

8 868 Endodontics 34 to 630 days. In the histologic sections, four layers could be demonstrated (Figure 17-5): (1) carious decalcified dentin, (2) rhythmic layers of irregular reparative dentin, (3) regular tubular dentin, and (4) normal pulp with a slight increase in fibrous elements. Clinical studies have shown no significant differences in the ultimate success of this technique regardless of whether calcium hydroxide or ZOE cement is used over residual carious dentin However, Torstenson et al. demonstrated slight to moderate inflammation when ZOE was used in deep unlined cavities that were less than 0.5 mm to the pulp itself. 58 Nordstrom and colleagues reported that carious dentin, wiped with a 10% solution of stannous fluoride for 5 minutes and covered with ZOE, can be remineralized. 59 It was further stated that no particular difference was found in failure rates of teeth treated with calcium hydroxide and those treated with stannous fluoride. As so many others have also concluded, the results for primary and young permanent teeth do not differ significantly (see Table 17-1). King and associates, 60 as well as Aponte et al. 61 and Parikh et al., 62 determined that the residual layer of carious dentin, left in the indirect pulp-capping technique, can be sterilized with either ZOE cement or calcium hydroxide. However, it cannot be presumed that all of the remaining infected or affected dentin Figure 17-5 Photomicrograph of four layers of healing under indirect pulp capping of a permanent molar of a year-old child. Zinc oxide eugenol cement capping after excavation of the necrotic dentin layer only. No pain 480 days later when extracted. 1 = carious decalcified dentin; 2 = rhythmic layers of irregular irritational dentin; 3 = regular tubular dentin; 4 = normal pulp with slight increase in fibrous elements. Reproduced with permission from Held-Wydler E. 54 becomes remineralized. In contrast to ZOE, residual dentin will increase in mineral content when in contact with calcium hydroxide. 63,64 Sawusch evaluated calcium hydroxide liners for indirect pulp capping in primary and young permanent teeth. After periods ranging from 13 to 21 months, he concluded that Dycal was a highly effective agent. 65 Nirschl and Avery reported greater than 90% success rates for both Dycal and LIFE (SybronEndo/Kerr Corp.; Orange, Calif.) calcium hydroxide preparations when used as bases in both primary and permanent teeth for indirect pulp-capping therapy. 66 Coll et al., in an evaluation of several modes of pulp therapy in primary incisors, stated that the success rates of indirect pulp cappings in primary incisors did not differ from comparable molar rates. 67 They showed a 92.3% success rate for treated incisors after a mean follow-up time of 42 months. The medicament choice for indirect pulp capping can be based on the clinical history of the carious tooth in question. Some investigators recommend ZOE because of its sealing and obtundant properties, which reduce pulp symptoms. Others recommend calcium hydroxide because of its ability to stimulate a more rapid formation of reparative dentin. Stanley believes that it makes no difference which is used because neither is in direct contact with pulp tissue, and increased dentin thickness was observed to occur beneath deep lesions treated with both agents. 57 However, in case of an undetected microscopic pulp exposure during caries excavation, calcium hydroxide will better stimulate a dentinal bridge. 57,68 Primosch et al. noted that the majority of US pediatric dentistry undergraduate programs used calcium hydroxide as the principal indirect pulp capping medicament in their teaching protocols. 69 Lado and Stanley demonstrated that light-cured calcium hydroxide compounds were equally effective in inhibiting growth of organisms commonly found at the base of cavity preparations. 70 A minimum indirect pulp post-treatment time period of 6 to 8 weeks should be allowed to produce adequate remineralization of the cavity floor. 7,17,71 This desirable outcome is essentially dependent on the maintenance of a patent seal against microleakage by the temporary and final restorations. In this regard, the newer resin-reinforced glass ionomer cements and dentin bonding agents should be considered. DIRECT PULP CAPPING Direct pulp capping involves the placement of a biocompatible agent on healthy pulp tissue that has been inadvertently exposed from caries excavation or trau-

9 Pediatric Endodontics 869 Figure 17-6 Direct pulp-capping technique. A, Capping material covers pulp exposure and the floor of the cavity. B, Protective base of zinc oxide eugenol cement. C, Amalgam restoration. matic injury 72 (Figure 17-6). The treatment objective is to seal the pulp against bacterial leakage, encourage the pulp to wall off the exposure site by initiating a dentin bridge, and maintain the vitality of the underlying pulp tissue regions (Figure 17-7). Case Selection Success with direct pulp capping is dependent on the coronal and radicular pulp being healthy and free from bacterial invasion. 73,74 The clinician must rely on the physical appearance of the exposed pulp tissue, radiographic assessment, and diagnostic tests to determine pulpal status. Indications. Tooth selection for direct pulp capping involves the same vital pulp therapy considerations mentioned previously, to rule out signs of irreversible pulp inflammation and degeneration. The classic indication for direct pulp capping has been for pinpoint mechanical exposures that are surrounded with sound dentin. 3,7,21 24 The exposed pulp tissue should be bright red in color and have a slight hemorrhage that is easily controlled with dry cotton pellets applied with minimal pressure. Frigoletto noted that small exposures and a good blood supply have the best healing potential. 75 Although imprecise, the term pinpoint conveys the concept of smallness to the exposed tissue, which should have the lowest possibility of bacterial access. An empirical guideline has been to limit the technique to exposure diameters of less than 1 mm. Stanley has A B C D Figure 17-7 Effect of calcium hydroxide and time on the healing of the capped pulp. A, Twenty-four hours after application of calcium hydroxide. B, After 2 or 3 weeks. C, After 4 or 5 weeks. D, After 8 weeks. Reproduced with permission from Vermeersch AG. 107

10 870 Endodontics determined, however, that the size of the exposure is less significant than the quality of the capping technique in avoiding contamination and mechanical trauma to the exposure site and careful application of the medicament to hemostatically controlled pulp tissue. 74 Equally important is the quality of the temporary or permanent restoration to exclude microleakage. Contraindications. Contraindications to direct pulp-capping therapy include a history of (1) spontaneous and nocturnal toothaches, (2) excessive tooth mobility, (3) thickening of the periodontal ligament, (4) radiographic evidence of furcal or periradicular degeneration, (5) uncontrollable hemorrhage at the time of exposure, and (6) purulent or serous exudate from the exposure. Clinical Success The salient features of a clinically successful direct pulpcapping treatment (with or without bridging) are (1) maintenance of pulp vitality, (2) absence of sensitivity or pain, (3) minimal pulp inflammatory responses, and (4) absence of radiographic signs of dystrophic changes. Permanent Teeth. Several investigators have provided evidence that direct pulp capping cannot be successful in the presence of pulpal inflammation and identify this condition as a contraindication to direct pulp capping. 2 Tronstad and Mjör capped inflamed pulps in monkey teeth with calcium hydroxide or ZOE and found no beneficial healing of the exposed pulp when calcium hydroxide was used. 76 More recently, however, other investigators have shown in animal studies that pulp healing can take place irrespective of the presence of overt inflammation. 77,78 Cotton observed that when there is minimal pulp inflammation, a bridge may form against the capping material, but when inflammation is more severe, the bridge is apt to form at a distance from the exposure. 79 Dentin bridge formation has been considered to be the sine qua non for success in response to direct pulpcapping procedures. 73,80 82 Weiss and Bjorvatn have demonstrated, however, that a healthy pulp can exist beneath a direct pulp cap even in the absence of a dentinal bridge. 83 Kakehashi et al., in a germ-free animal study, found pulp exposure healing with bridging even when left uncovered 84 (Figure 17-8). Seltzer and Bender 42 and Langeland et al. 85 have shown that a dentin bridge is not as complete as it appears, which can ultimately lead to untoward pulp reactions. Cox and Subay found that 89% of bridges formed in response to calcium hydroxide direct pulp caps demonstrated tunnel defects, which allowed access of microleakage products beneath the restoration into the pulp. They found recurrent pulp inflammation beneath 41% of all bridges formed in the sample. 86 It is generally considered that pulps inadvertently exposed and asymptomatic in the preoperative period are more apt to survive when capped. The prognosis is far less favorable if an attempt is made to cap an inflamed pulp infected from caries or trauma. 87 Also, the wide-open apices and high vascularity of young permanent teeth enhance the successful outcome of direct capping techniques. A B Figure 17-8 Role of bacteria in dentin repair following pulp exposure. A, Germ-free specimen, obtained 14 days after surgery, with food and debris in occlusal exposure. Nuclear detail of the surviving pulp tissue (arrow) can be observed beneath the bridge consisting of dentin fragments united by a new matrix. B, Intentional exposure of a first molar in a control rat (with bacteria) 28 days postoperatively. Complete pulp necrosis with apical abscess. A reproduced with permission from Kakehashi S et al. 84 B reproduced with permission from Clark JW and Stanley HR. Clinical dentistry. Hagerstown (MD): Harper & Row; 1976.

11 Pediatric Endodontics 871 Primary Teeth. Kennedy and Kapala attributed the high cellular content of pulp tissue to be responsible for direct pulp-capping failures in primary teeth. 88 Undifferentiated mesenchymal cells may give rise to odontoclastic cells in response to either the caries process or the pulp-capping material, resulting in internal resorption. Because of the pulp cellular content, increased inflammatory response, and increased incidence of internal resorption, some pediatric dentists feel that the direct capping procedure is contraindicated in primary teeth. 27,89,90 Starkey and others feel that a high degree of success with direct pulp capping in primary teeth can be achieved in carefully selected cases using specific criteria and treatment methods Treatment Considerations Débridement. Kalins and Frisbee have shown that necrotic and infected dentin chips are invariably pushed into the exposed pulp during the last stages of caries removal. 95 This debris can impede healing in the area by causing further pulpal inflammation and encapsulation of the dentin chips. Therefore, it is prudent to remove peripheral masses of carious dentin before beginning the excavation where an exposure may occur. When an exposure occurs, the area should be appropriately irrigated with nonirritating solutions such as normal saline to keep the pulp moist. 81 Hemorrhage and Clotting. Hemorrhage at the exposure site can be controlled with cotton pellet pressure. A blood clot must not be allowed to form after the cessation of hemorrhage from the exposure site as it will impede pulpal healing. 96 The capping material must directly contact pulp tissue to exert a reparative dentin bridge response. Hemolysis of erythrocytes results in an excess of hemosiderin and inflammatory cellular infiltrate, which prolongs pulpal healing. 74 Exposure Enlargement. There have been recommendations that the exposure site be enlarged by a modification of the direct capping technique known as pulp curettage or partial pulpotomy prior to the placement of the capping material. 3,93,96,97 Enlarging this opening into the pulp itself serves three purposes: (1) it removes inflamed and/or infected tissue in the exposed area; (2) it facilitates removal of carious and noncarious debris, particularly dentin chips; and (3) it ensures intimate contact of the capping medicament with healthy pulp tissue below the exposure site. Cvek 98 and Zilberman et al. 99 have described highly favorable results with this partial pulpotomy technique for pulp-exposed, traumatized, anterior teeth and carious molars. After a 24-month waiting period, Mejare and Cvek were able to show a 93.5% success rate of partial pulpotomy in permanent posterior teeth with deep carious lesions with exposed pulps. 100 Fuks et al. found similar partial pulpotomy success rates above 90% in permanent incisors with fracture-exposed pulps. 101 Bacterial Contamination. Watts and Paterson 102 and Cox 103 have both emphasized the fact that bacterial microleakage under various restorations causes pulpal damage in deep lesions, not the toxic properties of the cavity liners and/or restorative materials. The success of pulp-capping procedures is dependent on prevention of microleakage by an adequate seal. Cox et al. have shown that pulp healing is more dependent on the capacity of the capping material to prevent bacterial microleakage rather than the specific properties of the material itself. 104 Medications and Materials. Many medicaments and materials have been suggested to cover pulp exposures and initiate tissue healing and/or hard structure repair. Calcium hydroxide, in one form or another, has been singled out by a myriad of authors as the medicament of choice for pulp exposures. 80,82,105,106 Antibiotics, calcitonin, collagen, corticosteroids, cyanoacrylate, formocresol, and resorbable tricalcium phosphate ceramic have also been investigated, with varying degrees of success. These latter compounds, with the exception of formocresol, have not had sufficient clinical impact to be adopted as the material of choice in direct pulp capping, especially in the pediatric age groups. Calcium Hydroxide. Calcium hydroxide produces coagulation necrosis at the contact surface of the pulp. The underlying tissue then differentiates into odontoblasts, which elaborate a matrix in about 4 weeks. 107 This results in the formation of a reparative dentin bridge, caused by the irritating quality of the highly alkaline calcium hydroxide, which has a ph of 11 to Stanley has identified that the dentin bridging effects of calcium hydroxide occur only when the agent is in direct contact with healthy pulp tissue. 74 Tamburic et al. summarized the mineralizing effects of calcium hydroxide, which include cellular adenosine triphosphate activation resulting from calcium and hydroxyl ion enhancement of alkalinity in the mineralization process. 109 Yoshiba et al. provided immunofluorescence evidence of the possible contribution of calcium hydroxide to odontoblastic differentiation. They found increased amounts of fibronectin, an extracellular glycoprotein implicated in cell differentiation, among migrating fibroblasts and newly formed odontoblasts in areas of initial bridge calcification in response to calcium hydroxide. They noted that although calcium

12 872 Endodontics hydroxide was not unique in initiating reparative dentinogenesis, it demonstrated the most rapid tubular dentin formation in comparison to calcium phosphate ceramics and tricalcium phosphate. 110 Calcium hydroxide has significant antibacterial action, which has been identified as an additional benefit in capping procedures. 111,112 Estrela et al. summarized the antibacterial properties of calcium hydroxide, which include hydrolyzing bacterial cell wall lipopolysaccharides, neutralizing bacterial endotoxins, and reducing anaerobic organisms through carbon dioxide absorption. 113 There is some controversy as to the source of calcium ions necessary for dentinal bridge repair at the exposure site. Sciaky and Pisanti 114 and Attalla and Noujaim 115 demonstrated that calcium ions from the capping material were not involved in the bridge formation. Stark and his colleagues, however, believe that calcium ions from the capping medicament do enter into bridge formation. 116 Holland et al. provided additional evidence to support this concept. 117 Seltzer and Bender identified the osteogenic potential of calcium hydroxide. 42 It is capable of inducing calcific metamorphosis, resulting in obliteration of the pulp chamber and root canals. This fact has raised concern among clinicians. 42 Lim and Kirk, in an extensive review of direct pulp capping literature, found little support for pulp obliteration and internal resorption being a major complication of pulp capping. 81 Although internal resorption has been documented following calcium hydroxide pulpotomies in primary teeth, it does not appear to be a problem in permanent teeth. Jeppersen, in a long-term study using a creamy mix of calcium hydroxide placed on exposed pulps of primary teeth, reported a 97.6% clinical success and 88.4% histologic success. 93 Although calcium hydroxide pastes have been shown to be effective in promoting dentin bridges, their higher ph, water solubility, and lack of physical barrier strength led manufacturers to introduce modified calcium hydroxide cements that set quickly and hard for lining cavities and pulp capping. Various studies have shown successful results of up to 80% with calcium hydroxide pulp capping of involved primary teeth with or without coronal inflammation. 65,94,96,118 These investigations support the use of hard-set calcium hydroxide cements in place of calcium hydroxide pastes without causing pathologic sequelae, such as internal resorption, associated with pulp-capping failure. For example, the so-called necrobiotic and inflammatory zones are minimal, and dentin bridges seem to form directly under these commercial compounds instead of at a distance from the paste forms. 82,118,119 Antibacterial properties and physical strength to support amalgam condensation have been shown for the hard-set calcium hydroxide cements. 51,103,120 After a clinical investigation of two formulas of a hard, self-setting calcium hydroxide compound (Dycal), Sawusch found calcium hydroxide liners to be effective agents for direct and indirect pulp capping in both primary and young permanent teeth. 65 He also found that failures in this study tended to be associated with failed restorations and microleakage. Fuks et al. observed an 81.5% success in young permanent fractured teeth with pinpoint exposures when calcium hydroxide was the capping material of choice. 121 With the advent of visible light-curing restorative resins, it was inevitable that, in the interest of efficiency and improving the hardness of a cavity lining material, light-cured calcium hydroxide pulp-capping products were introduced. Stanley and Pameijer 122 and Seale and Stanley, 123 in histologic studies, found that a calcium hydroxide product (Prisma VLC Dycal, L. D. Caulk Co.), cured by visible light, maintained all of the characteristics of healing and bridge formation equivalent to the original self-curing Dycal. Lado, in an in vitro study comparing the bacterial inhibition of these new light-cured products to the self-setting calcium hydroxide cements, also found no differences. 112 Howerton and Cox reported the same results as Stanley and Pameijer 122 and Seale and Stanley 123 using light-cured calcium hydroxide in monkeys. 124 Alternative Agents to Calcium Hydroxide Suggested for Direct Pulp Capping in Primary and Permanent Teeth Zinc Oxide Eugenol Cement. Glass and Zander found that ZOE, in direct contact with the pulp tissue, produced chronic inflammation, a lack of calcific barrier, and an end result of necrosis. 80 Hembree and Andrews, in a literature review of ZOE used as a direct pulp-capping material, could find no positive recommendations. 125 Watts also found mild to moderate inflammation and no calcific bridges in the specimens under his study, 126 and this was confirmed by Holland et al. 127 Weiss and Bjorvatn, on the other hand, noted negligible necrosis of the pulp in direct contact with ZOE but stated that any calcific bridging of an exposure site was probably a layer of dentinal chips. 83 They also found no apparent difference in the pulp reactions of primary and permanent teeth. In spite of the reported lack of success with ZOE cement, Sveen reported 87% success with the capping of primary teeth with ZOE in ideal situations of pulp

13 Pediatric Endodontics 873 exposure. 128 He offered no histologic evidence, but Tronstad and Mjör, comparing ZOE with calcium hydroxide, found ZOE more beneficial for inflamed, exposed pulps and felt that the production of a calcific bridge is not necessary if the pulp is free of inflammation following treatment. 76 Corticosteroids and Antibiotics. Corticosteroids and/or antibiotics were suggested for direct pulp capping in the pretreatment phase and also to be mixed in with calcium hydroxide with the thought of reducing or preventing pulp inflammation. These agents included neomycin and hydrocortisone, 129 Cleocin, 130 cortisone, 131 Ledermix (calcium hydroxide plus prednisolone), 132 penicillin, 133 and Keflin (cephalothin sodium). 134 Although many of these combinations reduced pain for the most part, they were found only to preserve chronic inflammation and/or reduce reparative dentin. Also, Watts and Paterson cautioned that anti-inflammatory compounds should not be used in patients at risk from bacteremia. 135 Gardner et al. found, however, that vancomycin, in combination with calcium hydroxide, was somewhat more effective than calcium hydroxide used alone and stimulated a more regular reparative dentin bridge. 136 Polycarboxylate Cements. These cements have also been suggested as a direct capping material. The material was shown to lack an antibacterial effect and did not stimulate calcific bridging in the pulps of monkey primary and permanent teeth. 134 Negm et al. placed calcium hydroxide and zinc oxide into a 42% aqueous polyacrylic acid and used this combination for direct pulp exposure in patients from 10 to 45 years of age. This mixture showed faster dentin bridging over the exposures in 88 to 91% of the patients when compared to Dycal as the control. 137 Inert Materials. Inert materials such as isobutyl cyanoacrylate 138 and tricalcium phosphate ceramic 139 have also been investigated as direct pulp-capping materials. Although pulpal responses in the form of reduced inflammation and unpredictable dentin bridging were found, to date, none of these materials have been promoted to the dental profession as a viable technique. At Istanbul University, dentists capped 44 pulps, half with tricalcium phosphate hydroxyapatite and half with Dycal (calcium hydroxide). At 60 days, none of the hydroxyapatite-capped pulps exhibited hard tissue bridging but instead had mild inflammation. Nearly all of the Dycal-capped pulps, however, were dentin bridged, with little or no inflammation. 140 Collagen Fibers. Because collagen fibers are known to influence mineralization, Dick and Carmichael placed modified wet collagen sponges with reduced antigenicity in pulp-exposed teeth of young dogs. 141 Although the material was found to be relatively less irritating than calcium hydroxide, and with minimal dentin bridging in 8 weeks, it was concluded that collagen was not as effective in promoting a dentin bridge as was calcium hydroxide. Fuks et al. did find dentin bridges after 2 months in 73% of pulpotomized teeth that had been capped with an enriched collagen solution. 142 They felt that a different mechanism exists for the production of a truer dentin when a collagen solution is used rather than with calcium hydroxide because no coagulation necrosis was seen. Formocresol. Because of the clinical success of formocresol when used in primary pulp therapy such as pulpotomies and pulpectomies, several investigators have been intrigued by the possibility of its use as a medicament in direct pulp-capping therapy. Arnold applied full-strength formocresol for 2 minutes over enlarged pulp exposures in primary teeth and found a 97% clinical success after 6 months. 97 Ibrahim et al. reported the absence of inflammation along with dentin bridging in 15 experimental teeth when exposures were medicated with formocresol for 5 minutes and capped with a mixture of formocresol and ZOE cement. 143 More recently, Garcia-Godoy obtained a 96% clinical and radiographic success rate in human exposed primary molars when capped with a paste of one-fifth diluted formocresol mixed with a ZOE paste and covered with a reinforced ZOE cement. 144 Hybridizing Bonding Agents. Recent evidence has shown that elimination of bacterial microleakage is the most significant factor affecting restorative material biocompatibility. 145,146 A major shortcoming of calcium hydroxide preparations is their lack of adhesion to hard tissues and resultant inability to provide an adequate seal against microleakage. 9,147 Furthermore, calcium hydroxide materials have been found to dissolve under restorations where microleakage has occurred, resulting in bacterial access to the pulp. 148 Currently, hybridizing dentinal bonding agents (such as AmalgamBond or C & B MetaBond, Parkell Products, Farmingdale, N.Y.) represent the state of the art in mechanical adhesion to dentin with resultant microleakage control beneath restorations. 9,149,150 Miyakoshi and et al. have shown the effectiveness of 4-META-MMA-TBB adhesives in obtaining an effective biologic seal. 151 Cox et al. demonstrated that pulps sealed with 4-META showed reparative dentin deposition without subjacent pulp pathosis. 152,153 A number of investigators have proposed that sealing vital pulp exposures with hybridizing dentin bonding agents may provide a superior outcome to calcium hydroxide direct pulp-capping techniques. 9,154 Because

14 874 Endodontics of their superior adhesion to peripheral hard tissues, an effective seal against microleakage can be expected. These proposals have been made in spite of concerns with the effects of acid etchant and resin materials on pulp tissue. Snuggs et al. demonstrated that pulpal healing occurred, with bridge formation, in exposed primate teeth capped with acidic materials such as silicate cement and zinc phosphate cement. This was contingent on the fact of the biologic surface seal of the overlying restoration remaining intact. 147 Kashiwada and Takagi demonstrated 60 of 64 teeth to be vital and free of any clinical and radiographic signs of pulp degeneration 12 months after pulp capping with a resin bonding agent and composite resin. The pulp tissue was not exposed to acid conditioner during the technique. Selected third molars receiving this treatment were histologically studied and demonstrated dentin bridge formation below the area of exposure. 155 Heitman and Unterbrink studied a glutaraldehydecontaining dentin bonding agent, in direct pulp-capping exposed pulps, in eight permanent teeth. All exposed pulps were protected with calcium hydroxide during application of the acid conditioner. After rinsing away the calcium hydroxide dressing and conditioner, the bonding agent was applied directly to the exposed pulp tissue and surrounding dentin. All teeth were vital after a 6-month postoperative period. 156 These results have been further substantiated by Cox and White and Bazzuchi et al. 153,157 Kanca reported a 4-year clinical and radiographic success with dentin bonding agent application following etching material applied directly to a fracture-induced exposed pulp and dentin in rebonding a tooth fragment. 158 Conversely, other investigators provide conflicting evidence that does not support using dentin bonding agents in pulp-capping techniques. Stanley has stated that acid conditioning agents can harm the pulp when placed in direct contact with exposed tissues. 159 In a primate tooth sample with pulp exposures treated with total-etch followed by application of a dentin bonding agent, Pameijer and Stanley found that 45% became nonvital and 25% exhibited bridge formation after 75 days. In the no etch calcium hydroxide pulp-capping sample, 7% became nonvital and 82% exhibited bridge formation after the same time period. 160 After 1 year, Araujo et al. experienced a clinical and radiographic success rate of 81% in primary tooth exposures etched and capped with resin adhesives. Histologic assessment of extracted sample teeth in advent of their exfoliation demonstrated inflammatory infiltrate, microabscess formation, and no dentin bridging. Furthermore, bacterial penetration occurred in 50% of the histologically studied teeth. This occurred in spite of the final composite resin restorations being resealed at 6-month intervals from the time of initial placement. 161 Gwinnett and Tay, using light microscopic and electron microscopic techniques, identified early and intermediate pulp responses to total-etch followed by a resin bonding agent and composite resin restoration in human teeth. Some specimens demonstrated signs of initial repair with dentin bridge formation along the exposed site and reparative dentin adjacent to the exposed site. Other specimens demonstrated persistence of chronic inflammation with a foreign body response in the form of resin globules imbedded within the exposed pulp tissue that were surrounded by pulpal macrophages. This was also accompanied by a mononuclear inflammatory infiltrate and an absence of calcific bridge formation. 162 Although using dentin bonding agents as a replacement for calcium hydroxide in the direct pulp-capping technique has been advocated, 163 more long-term evidence and histologic evaluation are needed. Until such evidence is available, the clinician would be prudent to employ a combination of calcium hydroxide as a medicament for the exposed pulp followed by a hybridizing resin bonding agent for a successful microbiologic seal. 164,165 This concept is further substantiated by Katoh et al., who reported improved direct pulp-capping results with dentin bonding agents when they were used in conjunction with calcium hydroxide. 166,167 Cell-Inductive Agents. A number of cell-inductive agents have been proposed as potential direct pulp-capping alternatives to calcium hydroxide. These contemporary substances mimic the reciprocal inductive activities seen in embryologic development and tissue healing that are receiving so much attention at this time. Mineral trioxide aggregate (MTA) (Dentsply, Tulsa; Tulsa, Okla.) cement was developed at Loma Linda by Torabinejad for the purposes of root-end filling and furcation perforation repair. 168 The material consists of tricalcium silicate, tricalcium aluminate, tricalcium oxide, and silicate oxide. It is a hydrophilic material that has a 3-hour setting time in the presence of moisture. Major MTA advantages include excellent sealing ability, good compressive strength (70 MPa) comparable to IRM, and good biocompatibility. Pitt Ford et al. documented superior bridge formation and preservation of pulp vitality with MTA when compared with calcium hydroxide in a direct pulp-capping technique. 169 They also reported normal cytokine activity in bone and cementum regeneration in response to MTA, which is indicative of its cell-inductive potential. 169

15 Pediatric Endodontics 875 Calcium phosphate cement has been developed for repairing cranial defects following brain neurosurgery. The components of this material include tetracalcium phosphate and dicalcium phosphate, which react in an aqueous environment to form hydroxyapatite, the mineral component of hard tissues. Chaung et al. histologically compared calcium phosphate cement with calcium hydroxide as a direct pulp-capping agent. Although both materials produced similar results with respect to pulp biocompatibility and hard tissue barrier formation, calcium phosphate cement was suggested as a viable alternative because of (1) its more neutral ph resulting in less localized tissue destruction, (2) its superior compressive strength, and (3) its transformation into hydroxyapatite over time. 170 Yoshimine et al. demonstrated the potential benefits of direct pulp capping with tetracalcium phosphate based cement. As with calcium phosphate cement, this material has the ability to be gradually converted into hydroxyapatite over time. In contrast to calcium hydroxide, tetracalcium phosphate cement induced bridge formation with no superficial tissue necrosis and significant absence of pulp inflammation. 171 Summary: Direct Pulp Capping. Adherence to established criteria for case selection is important to achieve success. Although somewhat controversial based on the previously reviewed studies, direct pulp capping has been found to be less successful in primary teeth than indirect pulp therapy or coronal pulpotomy. However, direct pulp capping tends to be more successful in young permanent teeth. PULPOTOMY Pulpotomy is the most widely used technique in vital pulp therapy for primary and young permanent teeth with carious pulp exposures. A pulpotomy is defined as the surgical removal of the entire coronal pulp presumed to be partially or totally inflamed and quite possibly infected, leaving intact the vital radicular pulp within the canals. 2 A germicidal medicament is then placed over the remaining vital radicular pulp stumps at their point of communication with the floor of the coronal pulp chamber. This procedure is done to promote healing and retention of the vital radicular pulp. Dentin bridging may occur as a treatment outcome of this procedure depending on the type of medicament used (Figure 17-9). Additional variables thought to influence treatment outcome include the medication type, concentration, and time of tissue contact. Indications. According to Dannenberg, pulpotomies are indicated for cariously exposed primary teeth when their retention is more advantageous than extraction and replacement with a space maintainer. 172 Pulpotomy candidates should demonstrate clinical and radiographic signs of radicular pulp vitality, absence of pathologic change, restorability, and at least two-thirds remaining root length. Pulpotomized teeth should receive stainless steel crowns as final restorations to avoid potential coronal fracture at the cervical region. Pulpotomy is also recommended for young permanent teeth with incompletely formed apices and cariously exposed pulps that give evidence of extensive coronal tissue inflammation. Contraindications. According to Mejare, contraindications for pulpotomy in primary teeth exist when (1) root resorption exceeds more than one-third of the root length; (2) the tooth crown is nonrestorable; (3) highly viscous, sluggish, or absent hemorrhage is observed at the radicular canal orifices; as well as (4) marked tenderness to percussion; (5) mobility with locally aggravated gingivitis associated with partial or total radicular pulp necrosis exists; and (6) radiolucency exists in the furcal or periradicular areas. 173 Figure 17-9 Dentin bridge following calcium hydroxide pulpotomy with LIFE. (Courtesy of SybronEndo/Kerr Orange, Ca.)

16 876 Endodontics Persistent toothaches and coronal pus should also be considered contraindications. Treatment Approaches for Primary Teeth. Ranly, in reviewing the rationale and various medicaments that have guided the historical development of the pulpotomy procedure, provided three categories of treatment approaches. Devitalization was the first approach to be used with the intention of mummifying the radicular pulp tissue. 174 The term mummified has been ascribed to chemically treated pulp tissue that is inert, sterilized, metabolically suppressed, and incapable of autolysis. 174 This approach involved the original two-sitting formocresol pulpotomy, which resulted in complete devitalization of the radicular pulp. Also included were the 5-minute formocresol and 1:5 diluted formocresol techniques, which both result in partial devitalization with persistent chronic inflammation. 174,175 The preservation approach involved medicaments and techniques that provide minimal insult to the orifice tissue and maintain the vitality and normal histologic appearance of the entire radicular pulp. Pharmacotherapeutic agents included in this category are corticosteroids, glutaraldehyde, and ferric sulfate. Nonpharmacotherapeutic techniques in this category include electrosurgical and laser pulpotomies. 174 The regeneration approach includes pulpotomy agents that have cell-inductive capacity to either replace lost cells or induce existent cells to differentiate into hard tissue forming elements. Historically, calcium hydroxide was the first medicament to be used in a regenerative capacity because of its ability to stimulate hard tissue barrier formation. The calcium hydroxide pulpotomy is predicated on the healing of pulp tissue beneath the overlying dentin bridge. Recently, its regenerative capacity has been questioned owing to the fact that calcium hydroxide tissue response is more reactive than inductive. Examples of true cell-inductive agents include transforming growth factor-β (TGF-β) in the form of bone morphogenetic proteins, 176,177 freeze-dried bone, 178 and MTA. 168,169 These materials are more representative of the regeneration category and provide the direction for future research in vital pulp therapy. 174 Formocresol Pulpotomy Formocresol was introduced in 1904 by Buckley, who contended that equal parts of formalin and tricresol would react chemically with the intermediate and end products of pulp inflammation to form a new, colorless, and non-infective compound of a harmless nature. 179 Buckley s formula, formocresol, consists of tricresol, 19% aqueous formaldehyde, glycerine, and water. * The formocresol pulpotomy technique currently used is a modification of the original method reported by Sweet in By 1955, Sweet claimed 97% clinical success in 16,651 cases. 181 It should be noted, however, that in this report, about one half of the primary teeth exfoliated early. Histology. In spite of regional popularity, the multiple-visit pulpotomy did not receive wide acceptance because it was regarded as a nonvital or devitalization method. In addition, histologic studies to support its use were also lacking. It became overshadowed by the so-called vital pulpotomy for primary teeth using calcium hydroxide, which at that time was supported by clinical and histologic evidence. Interest in formocresol was renewed, however, with a reported increase in clinical failures and radiographic evidence of internal resorption with calcium hydroxide, even in the presence of dentinal bridging. 188 At the same time, improved clinical and histologic success rates were reported with formocresol. 182 In spite of histologic studies that showed formalin, creosol, and paraformaldehyde to be connective tissue irritants, it was recognized early that formocresol is an efficient bactericide. It was also found to have the ability to prevent tissue autolysis by the complex chemical binding of formaldehyde with protein. However, this binding reaction may be reversible as the protein molecule does not change in its basic overall structure. 175 Massler and Mansukhani conducted a detailed histologic investigation of the effect of formocresol on the pulps of 43 human primary and permanent teeth in multiple treatment intervals. 183 Fixation of the tissue directly under the medicament was apparent. After a 7- to 14-day application, the pulps developed three distinctive zones: (1) a broad eosinophilic zone of fixation, (2) a broad pale-staining zone with poor cellular definition, and (3) a zone of inflammation diffusing apically into normal pulp tissue. After 60 days, in a limited number of samples, the remaining tissue was believed to be completely fixed, appearing as a strand of eosinophilic fibrous tissue. 183 Emmerson et al. also described the action of formocresol on human pulp tissue. 184 They reported *The formocresol used in this technique may be obtained under the trade name Buckley s Formocresol (Roth, Chicago, IL). Composition: 35% cresol, 19% formalin in a vehicle of glycerine and water at a ph of approximately 5.1. To dilute formocresol to one-fifth strength, thoroughly mix three parts of glycerine with one part of distilled water. Add these four parts to one part of concentrated commercial formocresol compound.

17 Pediatric Endodontics 877 that the effect on the pulp varied with the length of time formocresol was in contact with the tissue. A 5-minute application resulted in surface fixation of normal tissue, whereas an application sealed in for 3 days produced calcific degeneration. They concluded that formocresol pulpotomy in primary pulp therapy may be classified as either vital or nonvital, depending on the duration of the formocresol application. Formocresol versus Calcium Hydroxide. Doyle et al. compared the formocresol pulpotomy technique with the calcium hydroxide technique in primary canines and found the formocresol technique to be 95% clinically successful at the end of 1 year. 182 Although fixation of pulp tissue and some loss of cellular definition were seen histologically, healthy, vital tissue existed in the apical third. The calcium hydroxide technique was considered to be 61% clinically successful, and dentin bridge formation was seen in 50% of the cases examined. Spedding et al. also studied these two medicaments in monkeys and produced essentially the same results as Doyle and colleagues. 185 Law and Lewis evaluated the clinical effectiveness of the formocresol technique over a 4-year period and reported a 93 to 98% success rate. Their failure rate was greatest between the first and second years. 186 Formocresol versus Zinc Oxide Eugenol. Berger compared the pulpotomy effects of using a one-appointment formocresol medication with those of ZOE paste alone on the amputated pulps of cariously exposed human primary molars. 187 Periods of evaluation ranged from 3 to 38 weeks postoperatively. Clinically and radiographically, 97% of the formocresol-treated teeth were judged successful, whereas only 58% of the teeth treated with ZOE were considered successful. Histologically, 82% of the formocresol group was judged successful, compared to total failure with ZOE. 187 An intriguing part of this study was the finding of a total absence of cellular detail in the apical third at 3 weeks, but by 7 weeks, connective tissue of a granular type had ingrown through the apical foramen. In specimens obtained after longer postoperative periods, granulation tissue progressively replaced the necrotic pulp tissue up to the coronal area. Small areas of resorption of the dentinal walls were also being replaced by osteodentin. 187 Spamer also conducted a histologic study of caries-free human primary canines following a one-appointment formocresol pulpotomy in which the final pulp covering was ZOE. 188 Again, the three typical zones were distinguishable, including the apical one-third tissue, which was normal and free of inflammatory reaction. Initially, Spamer observed an acute inflammatory reaction, succeeded by a chronic inflammatory response, proliferation of odontoblasts, and an increase in collagen fibers. By 6 months, deposition of mature dentin and vital tissue was seen throughout. 188 Formocresol Pulpotomy Outcomes: Primary Teeth. Rolling and Thylstrup reported a clinical 3-year follow-up study of pulpotomized primary molars using formocresol. 189 Their results showed a progressively decreasing survival rate of 91% at 3 months, 83% at 12 months, 78% at 24 months, and 70% at 36 months after treatment. These investigators concluded that although their rate of success was less than previous studies had shown, the formocresol method must be considered an acceptable clinical procedure compared with other methods. Possibly, bacterial microleakage over the longer time span accounted for their decreasing success rate. Rolling and coworkers, in later studies, investigated the morphologic and enzyme histochemical reactions of pulpotomies done with formocresol in human primary molars for periods ranging from 3 to 24 months and 3 to 5 years. 190,191 In these studies, a wide range of pulpal reactions occurred, from normal pulps to total chronic inflammation. In most instances, however, the pulp tissue in the apical region was vital with minimal inflammation, which was in agreement with many other studies. It was concluded from both studies that the formocresol method should be regarded as only a means to keep primary teeth with pulp exposures functioning for a relatively short period of time. Magnusson investigated therapeutic (ie, formocresol) pulpotomies and stated that his histologic examinations revealed early capricious diffusion of the medicament through the pulp tissue, producing chronic inflammation and no healing in the apical areas along with a small percentage of internal resorption. 192 From a biologic standpoint, Magnusson felt that formocresol was biologically inferior to calcium hydroxide in the pulpotomy technique as the latter manifested true signs of healing but in a low percentage in primary teeth. 192 Ranley and Lazzari concluded, however, that variations in the interpretation of histologic studies with formocresol, on either vital or nonvital tissue, are attributable to the length of exposure of the radicular tissue to the drug, but there is no true healing. 193 In general, the results of many histologic studies on the formocresol pulpotomy have shown that several distinct zones are usually present in the pulp following the application of the medicament:

18 878 Endodontics 1. Superficial debris along with dentinal chips at the amputation site 2. Eosinophil-stained and compressed tissue 3. A palely stained zone with loss of cellular definition 4. An area of fibrotic and inflammatory activity 5. An area of normal-appearing pulp tissue considered to be vital Formocresol Addition to Sub-base. Beaver et al. investigated the differences in pulp reactions between a 5-minute application of formocresol using sub-bases of either ZOE cement alone or with the addition of formocresol. 194 There was no appreciable difference in a histologic reaction of the remaining radicular pulp tissue under either of these two types of sub-bases. An alternative procedure reported clinically and histologically successful is to incorporate diluted formocresol into the ZOE dressing and then place it on the pulpal stumps instead of a moistened formocresol cotton pellet. 17,195,196 Ranly and Pope have shown in vitro and in vivo that formocresol can leach out from a ZOE sub-base when the two substances are combined. 197 They have suggested that the initial application of a formocresol-saturated cotton pellet on the pulp might be an unnecessary step. Formocresol Dilution. Venham suggested that formocresol might be reduced to one-quarter strength in the pulpotomy application. 198 The combined investigations of Straffon and Han 199,200 and Loos et al. 201 on the histologic and biochemical effects of formocresol introduced new thinking in this type of pulp therapy. Straffon and Han concluded from a study of connective tissue in hamster pulps exposed to formocresol that the medicament does not interfere with a prolonged recovery of connective tissue and may even suppress the initial inflammatory reaction. In a later report, they concluded that formocresol at 1:5 strength might be equally effective and possibly a less damaging pulpotomy agent. Loos and colleagues concurred with the previous work in a further study of diluted formocresol. 201 Morawa and colleagues, in a 5-year clinical study of 70 cases, found that the formocresol pulpotomy, using a 1:5 concentration, was as effective as a full concentration and also has the advantage of reduced postoperative complications in the periradicular region. In only five teeth was there limited radicular internal resorption. 202 Fuks and Bimstein used this one-fifth dilution of formocresol in a clinical and radiographic study of primary teeth over a period of 4 to 36 months. 203 The clinical success rate was reported at 94.3%, and 39% of 41 cases showed a slightly higher rate of premature root resorption. Twenty-nine percent had radiographic evi- dence of a root canal obliteration process. In a later study with rhesus monkeys, using full-strength formocresol compared with a 20% dilution, these investigators found the same premature root resorption but a milder pulpal inflammatory response with the diluted concentration. 204 Garcia-Godoy, however, did not find any differences histologically between fullstrength and a one-fifth dilution of formocresol when applied in several ways over the amputated pulps. 195 Outcomes. Citing an 80% success rate of primary molars pulpotomized with formocresol, Wright and Widmer also found early root resorption of the pulpotomized molars in comparison to the untreated antimeres. 205 The permanent successors, however, were not found to erupt significantly earlier, as has been previously reported. The hard tissue deposition or calcification of the root canal walls following a formocresol pulpotomy has also been observed radiographically in several other studies. 203,206,207 These findings imply that the use of formocresol does not result in a complete loss of pulp vitality. More recently, the findings of a retrospective radiographic study of the formocresol pulpotomy technique with a post-treatment time ranging from 24 to 87 months were reported by Hicks et al. 196 In this study, a ZOE paste into which full-strength formocresol was incorporated was placed in the pulp chamber after coronal amputation followed by restoration with a stainless steel crown. Based on radiographic evaluation criteria, which included abscess formation, radiolucencies, pathologic root resorption, calcific metamorphosis, and advanced or delayed exfoliation, the procedure was considered to be successful in 93.8% of the cases. Coll et al. compared the techniques of formocresol pulpotomy versus pulpectomy in primary incisors. They concluded that the pulpotomy was the preferred technique for these teeth. 67 Formocresol Pulpotomy Technique in Primary Teeth Correct diagnosis is essential to ensure the clinician that inflammation is limited to the coronal pulp. 208 Biopsy studies of pulp tissue removed from the opening of root canals under pulpotomies have demonstrated the unreliability of clinical assessments in primary teeth. 192 Radiographic examinations are therefore necessary to confirm the need for pulpotomy therapy in primary teeth. It is judicious to take bitewing and periradicular radiographs so that the depth of caries may be observed and the condition of the periradicular tissues determined. Mejare found only a 55% success rate in primary molars with either coronal or total chronic

19 Pediatric Endodontics 879 pulpitis that were treated by formocresol pulpotomy after years. 209 One-Appointment Pulpotomy. Indications. This method of treatment should be carried out only on those restorable teeth in which it has been determined that inflammation is confined to the coronal portion of the pulp. When the coronal pulp is amputated, only vital, healthy pulp tissue should remain in the root canals (Figure 17-10). Contraindications. Teeth with a history of spontaneous pain should not be considered. If profuse hemorrhage occurs on entering the pulp chamber, the one-step pulpotomy is also contraindicated. Other contraindications are pathologic root resorption, roots that are two-thirds resorbed or internal root resorption, interradicular bone loss, presence of a fistula, or presence of pus in the chamber (Figure 17-11). Procedure. 1. Anesthetize the tooth and tissue. 2. Isolate the tooth to be treated with a rubber dam. 3. Excavate all caries. 4. Remove the dentin roof of the pulp chamber with a high-speed fissure bur (Figure 17-12, A). 5. Remove all coronal pulp tissue with a slow-speed No. 6 or 8 round bur (Figure 17-12, B). Sharp spoon excavators can remove residual tissue remnants. 6. Achieve hemostasis with dry cotton pellets under pressure. 7. Apply diluted formocresol to the pulp on a cotton pellet for 3 to 5 minutes 210 (Figure 17-12, C). Figure Final failure of formocresol pulpotomy, mandibular first primary molar. Root resorption and interradicular bone loss (arrows) prior to treatment forecast eventual failure. The tooth was extracted. Reproduced with permission from Law DB, Lewis TM, Davis JM. An atlas of pedodontics. Philadelphia: WB Saunders; Place a ZOE cement base without incorporation of formocresol (Figure 17-12, D). 9. Restore the tooth with a stainless steel crown. Two-Appointment Pulpotomy. Indications. The two-appointment technique is indicated if there is (1) evidence of sluggish or profuse bleeding at the amputation site, (2) difficult-to-control bleeding, (3) slight purulence in the chamber but none at the amputation site, (4) thickening of the periodontal ligament, or (5) a history of spontaneous pain without other contraindications. The two-step pulpotomy can also be used when shorter appointments are necessary to facilitate patient management problems. Miyamoto suggested the two-appointment technique for uncoopera- A B Figure One-appointment formocresol pulpotomy. A, Root of the pulp chamber and coronal pulp removed. Cotton pellet with formocresol in place for 5 minutes. B, Successful formocresol pulpotomy 1 year following treatment. (A courtesy of Dr. Constance B. Greeley; B courtesy of Dr. Mark Wagner.)

20 880 Endodontics A B C D Figure Step-by-step technique in one-appointment formocresol pulpotomy. A, Exposure of pulp by roof removal. B, Coronal pulp amputation with a round bur. Hemostasis with dry cotton or epinephrine. C, Application of formocresol for 1 minute. Excess medicament is expressed from cotton before placement. D, Following formocresol removal, zinc oxide eugenol base and stainless steel crown are placed. tive children to minimize chair time, especially for the initial operative visit. 211 Contraindications. This technique should not be done for teeth that are (1) nonrestorable, (2) soon to be exfoliated, or (3) necrotic. Procedure. 1. The steps are the same as for the one-appointment procedure through step A cotton pellet moistened with diluted formocresol is sealed into the chamber for 5 to 7 days with a durable temporary cement. 3. At the second visit, the temporary filling and cotton pellet are removed and the chamber is irrigated with hydrogen peroxide. 4. A ZOE cement base is placed. 5. The tooth is restored with a stainless steel crown. As previously stated, Verco and Allen found no difference in the success rate between one-stage and two-stage procedures. 212 Avram and Pulver surveyed Canadian, American, and selected dental schools throughout the world as well as a limited number of pediatric dental specialists

21 Pediatric Endodontics 881 to determine medicament choice and clinician attitude toward pulpotomy therapy prevalent at the time of investigation. 213 The most prevalent medicament used in pediatric dental departments (40.8%) was full-strength formocresol, followed by 36% for the 1:5 dilution. This 1:5 dilution was used by 50% of the pediatric specialists, whereas 42% used-full strength formocresol. Primosch et al. surveyed predoctoral pediatric dentistry programs in 53 US dental schools to determine the prevalence and types of primary tooth pulp therapy techniques taught in those institutions. Formocresol was the most widely taught pulpotomy medicament, with 71.7% of the programs using diluted formocresol and 22.6% full-strength formocresol. Zinc oxide eugenol was the base material of choice for 92.4% of all programs surveyed. 69 Clinical experience has shown that pulpotomized primary molars are susceptible to cuspal and cervical fracture. For this reason, the restoration of choice is a well-fitted stainless steel crown. Additional advantages of this restoration include elimination of recurrent decay, elimination of intracoronal restoration fracture, and reduction of microleakage. Although composite resin restorations, incorporating the dentin bonding agents, have been proposed for pulpotomized primary molars, more studies are indicated to determine their effectiveness relative to stainless steel crowns. PULPOTOMY FOR YOUNG PERMANENT TEETH Treatment of severely decayed and pulpally involved young permanent teeth in the child or adolescent creates a dilemma. Complete endodontic therapy and a cast full-crown restoration have been considered to be the ideal treatment. However, this is time consuming and, in many instances, beyond the family financial resources. Most importantly, canal obturation for incompletely formed roots and open apices presents unique problems with conventional endodontic techniques. The relatively thin dentin walls of the large obturated canals place the tooth at greater risk for root fracture over time. In these instances, the treatment objective is to maximize the opportunity for apical development and closure, known as apexogenesis, and enhance continual root dentin formation. These objectives can occur only if the radicular pulp is maintained in a healthy state the intent of the pulpotomy technique. Although calcium hydroxide has been the most recommended pulpotomy medicament for pulpally involved vital young permanent teeth with incomplete apices, formocresol has also been proposed as an alternative. Formocresol The well-documented success with formocresol pulpotomies in primary teeth has led a number of clinicians to extrapolate the use of this medication in young permanent teeth with a vital or, in some instances, nonvital pulp status at the start of operative treatment. Canosa reported the widespread use of formocresol pulpotomy in Cuba for all restorable molars with vital pulps only. Restorable necrotic molars, as well as premolars and anterior teeth, received full root canal therapy. She reported an empirical success rate of 75% with formocresol pulpotomies. Those cases that failed were treated by endodontic cleaning, shaping, and filling (I Canosa, personal communication, March 1994). Ibrahim et al. studied the use of formocresol as a pulpotomy medication in the permanent teeth of two dogs and a monkey for up to 20 weeks. 214 Radiographically, no evidence of apical pathosis was seen. Histologically, calcification in the canal, continued apical closure, and partial bridging were noted. Areas of inflammation were replaced with connective tissue. Using formocresol, Trask reported clinical success treating 43 permanent teeth with necrotic pulps in an age range of 7 to 23 years. 215 Eight of these patients were under 10 years of age, when root apices are presumed to be still open. Trask sealed a small formocresol cotton pellet in the pulp chamber by amalgam restoration or stainless steel crown for an observed period of 14 to 33 months. The treated teeth were asymptomatic except in one instance in which the tooth had to be retreated in the same manner. He felt that the permanent tooth formocresol pulpotomy was a better alternative than extraction as conventional endodontics was economically unfeasible in this cohort of patients. He considered it to be a temporizing treatment only and not a substitute for complete root canal therapy, which was advocated at a later date. 215 Myers also conducted a clinical study of formocresol treatment in pulpless permanent molars. Sixty-six cases were evaluated clinically for periods of time ranging from 3 to 22 months. Fifty-six of the treated teeth (85%) radiographically demonstrated elimination or marked reduction of initial periradicular rarefaction. Three of the teeth (4.5%) showed no change in appearance, and seven teeth (10.6%) exhibited an increase in periradicular rarefaction. An important finding was the observation that all of the teeth treated with formocresol exhibited continued apexification and increase in root length. 216 Armstrong et al. found the same as well as intracanal calcification. 217 Fiskio undertook a 5-year clinical study of 148 permanent teeth, using either a one-step or two-step

22 882 Endodontics formocresol pulpotomy. 218 Ninety-one percent required no further treatment. In the remaining 9%, the initial use of formocresol did not prevent endodontic therapy at a later date. The age of the patients at the start of treatment had no significant effect. Spedding, in discussing the use of formocresol for permanent molars, stated that a plug of fixed tissues forms in the root canals that can easily be removed with endodontic instruments. 219 This is in contrast to teeth treated with calcium hydroxide. He concluded, however, that although few failures with formocresol had been reported in permanent teeth, this treatment rationale is empirical, and more definite information about failures is needed. Rothman observed 165 pulpotomized human permanent teeth for 2 years with a two-treatment formocresol medication. 220 He reported an average success rate of 71% as judged clinically and radiographically. Intracanal calcification was seen in only three teeth. Fuks et al., in studying radiographs of formocresol pulpotomies in young permanent teeth of monkeys at the end of 1 year, observed a favorable response with both full-strength and diluted medication for continuing root development and closed apices. 204 Histologically, mild internal resorption was seen at a later date. The investigators stated that neither concentration produced ideal results, but a milder degree of inflammation was seen in the diluted group. Schwartz, surveying a group of Canadian practitioners and faculty on the use of formocresol for pulpotomies in young permanent teeth, found that the respondents felt that the procedure was a compromise and that the teeth should be treated with conventional endodontics at a later date. 221 Muniz et al. histologically studied 26 young permanent teeth treated with the formocresol technique 5 to 20 months postoperatively. 222 This investigation was based on an earlier study by Muniz in which he found an overall success rate of 92% in both vital and nonvital permanent teeth. He found inflammation and necrosis in the cervical third but fibrosis and osteodentin predominantly in the apical third, a response that seems to indicate stages of biologic scar healing that probably require around 10 to 20 months to be seen. Akbar investigated the differences in formocresol pulpotomy in permanent teeth with acute and chronic pulpitis over a 5-year period. 223 On the basis of clinical criteria only, he found the treatment to be more successful in the acute pulpitis group (81%) than in the chronic pulpitis group (70%). In reviewing the literature on apical histologic response to formocresol pulpotomies, Nishino identi- fied a fallacy in extrapolating its success in primary teeth to its use in permanent teeth. 224 A consistent finding in pulpotomized primary teeth has been the ingrowth of connective tissue through the apex in a coronal direction through the pulpal areas of chronically inflamed and fibrosed tissue. He identified that favorable clinical responses could mask the reality of histologic pulpal degeneration. Late symptoms from pulp degeneration in pulpotomized primary teeth are eliminated owing to their exfoliation. Young permanent teeth, however, may have a greater potential for developing periradicular infection with this technique owing to the longer time exposure to the inflammatory degenerative process. Conversely, he hypothesized that the formocresol treatment might be effective because the open apical foramen of immature permanent teeth would be conducive to an ingrowth of connective tissue at the apex in the form of proliferating fibroblasts. 224 Because linear osteodentin calcification may develop as a response to formocresol pulpotomies over time, there has been considerable concern expressed by endodontists of the difficulty in renegotiating treated young permanent canals after the apices have closed. Calcium Hydroxide Calcium hydroxide was most favored as a pulpotomy agent in the 1940s and mid-1950s because it was thought to be more biologically acceptable owing to the fact that it promoted reparative dentin bridge formation and pulp vitality was maintained. This rationale was introduced by Teuscher and Zander in 1938, who described it as a vital technique. 225 Their histologic studies showed that the pulp tissue adjacent to the calcium hydroxide was first necrotized by the high ph (11 to 12) of the calcium hydroxide. This necrosis was accompanied by acute inflammatory changes in the underlying tissue. After 4 weeks, a new odontoblastic layer and, eventually, a bridge of dentin developed (Figure 17-13). Later investigations showed three identifiable histologic zones under the calcium hydroxide in 4 to 9 days: (1) coagulation necrosis, (2) deep-staining basophilic areas with varied osteodentin, and (3) relatively normal pulp tissue, slightly hyperemic, underlying an odontoblastic layer. As with direct pulp capping, the presence of a dentinal bridge is not the sole criterion of success. The bridge may be incomplete and may appear histologically as doughnut, dome, or funnel shaped or filled with tissue inclusions. 226,227 It is also possible for the remaining pulp to be walled off by fibrous tissue with no dentin bridge evident radiographically. Initial reports by Berk and Brown indicated a success rate

23 Pediatric Endodontics 883 A B Figure Calcium hydroxide pulpotomy, young permanent molar. A, Pulp of a first permanent molar exposed by caries (white arrow). B, Calcified dentin bridges (arrows) over vital pulp in canals. Note open apices. C, Pulp recession (arrows) and continued root development indicative of continuing pulp vitality. Reproduced with permission from McDonald RE. Dentistry for the child and adolescent. 2nd ed. St. Louis: CV Mosby; C with calcium hydroxide for primary and young permanent teeth in the range of 30 to 90%. 228,229 Calcium Hydroxide Pulpotomy Outcomes in Primary Teeth Via, in a 2-year study of calcium hydroxide pulpotomies in primary teeth, had only a 31% success, 230 and Law reported only a 49% success in a 1-year study. 231 In all investigations, failure was the result of chronic pulpal inflammation and internal resorption. Magnusson 192 and Schröder and Granath 232 found similar high failure rates with calcium hydroxide in pulpotomized primary molars. Internal resorption may result from overstimulation of the primary pulp by the highly alkaline calcium hydroxide. This alkaline-induced overstimulation could cause metaplasia within the pulp tissue, leading to the formation of odontoclasts (Figure 17-14). In addition, undetected microleakage could allow large numbers of bacteria to overwhelm the pulp and nullify the beneficial effects of calcium hydroxide. Schröder also evaluated the progress of 33 pulpotomized primary molars with calcium hydroxide as a wound dressing. 233 After 2 years, the success rate was 59%, with failures manifested as internal resorption. Histologic study revealed extra pulpal blood clots, over the amputated sites, which Schröder felt interfered with pulpal healing and dentin bridge formation. In spite of these earlier discouraging reports, Phaneuf et al. demonstrated significant primary tooth pulpotomy success with calcium hydroxide in commercial preparations such as Pulpdent (Pulpdent Corporation Figure Massive internal resorption (arrows) of primary mandibular molars after calcium hydroxide pulpotomy.

24 884 Endodontics of America; Watertown, Mass.) and Dycal. 106 The difference in pulp response to these commercial preparations might be attributed to their lower ph values. Calcium hydroxide incorporated in a methylcellulose base, such as Pulpdent, showed earlier and more consistent bridging than did other types of calcium hydroxide preparations. Berk and Krakow 234 and Schröder 233 have extensively studied calcium hydroxide pulpotomies and believe that the state of the pulp, surgical trauma, or amputation treatment may be more important than the calcium hydroxide per se in inducing success. At present, the calcium hydroxide pulpotomy technique cannot be generally recommended for primary teeth owing to its low success rate. 89,184,235 Permanent Tooth Pulpotomy: Indications and Contraindications Because of improved clinical outcomes, calcium hydroxide is the recommended pulpotomy agent for carious and traumatic exposures in young permanent teeth, particularly with incomplete apical closure (Figure 17-15). Following the closure of the apex, it is generally recommended that conventional root canal obturation be accomplished to avoid the potential long-term outcome of root canal calcification. 236 Procedure. 1. Anesthetize the tooth to be treated and isolate under a rubber dam. 2. Excavate all caries and establish a cavity outline. 3. Irrigate the cavity with water and lightly dry with cotton pellets. 4. Remove the roof of the pulp chamber with a high-speed fissure bur. 5. Amputate the coronal pulp with a large low-speed round bur or a high-speed diamond stone with a light touch Control hemorrhage with a cotton pellet applied with pressure or a damp pellet of hydrogen peroxide. 7. Place a calcium hydroxide mixture over the radicular pulp stumps at the canal orifices and dry with a cotton pellet. 8. Place quick-setting ZOE cement or resin-reinforced glass ionomer cement over the calcium hydroxide to seal and fill the chamber. 9. If the crown is severely weakened by decay, a stainless steel crown rather than an amalgam restoration should be used to prevent cusp fractures (Figure 17-16). ALTERNATIVES TO FORMOCRESOL IN PRIMARY TEETH Although diluted formocresol is currently the recommended agent for pulpotomy treatment for carious pulp exposures in vital primary teeth, some concern has been expressed regarding its use as a pulp medication because of its biocompatibility deficiencies. The formaldehyde component of the medicament and its A B Figure Calcium hydroxide pulpotomies in young permanent teeth. A, Crown fracture exposure of a central incisor. The apex was open at the time of pulpotomy. Note root growth, apical closure, and the dentin bridges (arrows). B, Partial root canal calcification (arrows) following pulpotomy in a young first permanent molar.

25 Pediatric Endodontics 885 Sandler et al. sealed in Cresatin as the medicament in pulpotomy and protected it with a covering of Cavit (Premier Dental Products, Plymouth Meeting, Mass.). 246 Clinically, only one failure occurred in their test group. Histologically, tissue fixation appeared at the amputation site, and the apical-third pulp demonstrated vital tissue in 84% of the 21 cases examined. Nevins et al. were very successful in producing dentin bridging and canal calcification using collagen-calcium phosphate gel cross-linked with 0.6% glutaraldehyde to increase firmness and fiber stability. 247 Fuks et al., using native collagen solutions enriched with cell nutrients that promote cell proliferation and healing of incision wounds, showed complete healing of pulpotomized teeth in dogs and monkeys. 142 Figure Calcium hydroxide pulpotomy in a young permanent molar. The cavity is prepared, caries and the chamber roof are removed, and the pulp is amputated to the canal orifices. Following hemostasis, commercial calcium hydroxide is placed and protected with zinc oxide eugenol and amalgam filling or a stainless crown. A, Vital pulp. B, Calcium hydroxide. C, Zinc oxide eugenol quick-set cement. D, Amalgam. close derivatives have been implicated for exerting potentially harmful systemic and local effects. Formocresol may not be confined solely to the radicular tissue. Various investigations by Pashley et al. 238 and Myers et al. 239 showed systemic uptake and tissue injury of labeled formaldehyde that was later found in dentin, periodontal tissue, bone, plasma, kidneys, and lungs. Ranly and Horn, in studying the ingredients and actions of formocresol, stated that although high levels of formaldehyde or cresol can be mutagenic or carcinogenic and produce histologic failures pulpally, it is not realistic that enough multiple pulpotomies would be performed to bring about a toxic systemic level. 240,241 Messer et al. reported a significant number of enamel defects in the succedaneous teeth under formocresol pulpotomies. 242 Rollings and Paulsen 243 and Mulder et al., 244 however, found no difference in the prevalence of enamel defects in permanent teeth in relation to formocresol pulpotomies. Because of the potential concerns in the use of formaldehyde in dentistry, it has been suggested that research in alternative formulations be conducted for use in pediatric pulpal therapy. 245 In spite of these concerns, formocresol remains as the benchmark medicament to which alternative agents are compared. Glutaraldehyde It was suggested by s-gravenmade that formaldehyde did not represent the ideal pulp fixative in clinical endodontic therapy. Inflamed tissue that produces toxic by-products should be fixed rather than treated with strong disinfectants. 248 He felt that satisfactory fixation with formocresol requires an excessive amount of medication, as well as a longer period of interaction. These requirements may lead to undesirable effects at the periapex. Also, the reactions of formaldehyde with proteins should be considered less than stable and may be reversible. He felt that a glutaraldehyde solution might replace formocresol in endodontic therapy because of its fixative properties and bactericidal effectiveness and result in less destruction of tissue. Hill et al. compared glutaraldehyde to formocresol in vitro with respect to its antimicrobial and cytotoxic effects. Minimal antimicrobial concentrations were 3.125% for glutaraldehyde and 0.75% for formocresol. More importantly, at these concentrations, glutaraldehyde was found to be less cytotoxic when used as a pulpotomy agent. Formocresol at its lower concentration, however, was considerably more antimicrobial than glutaraldehyde. 249 Wernes and s-gravenmade, in an in vivo study of permanent and primary dentitions, in which some teeth were vital and others nonvital, found no evidence of periradicular inflammation after the application of glutaraldehyde. 250 Dankert and colleagues found only minimal diffusion through the apices. 251 The following attributes have been ascribed to glutaraldehyde as a more desirable medicament for pulpal therapy when compared to formocresol: (1) it is a bifunctional reagent, which allows it to form strong intra- and intermolecular protein bonds, leading to

26 886 Endodontics superior fixation by cross-linkage; (2) its diffusibility is limited; (3) it is an excellent antimicrobial agent; (4) it causes less necrosis of pulpal tissue; and (5) it causes less dystrophic calcification in pulp canals. In an initial clinical study, Kopel and colleagues used a 2% glutaraldehyde solution as a medicament for pulpotomies in vivo for cariously exposed primary molars. 252 Histologic evaluations were made on extracted teeth at 1 month, 3 months, 6 months, and 1 year. The most striking finding from this study was that, histologically, the remaining root pulp tissue did not resemble pulp tissue subjected to formocresol. There was an initial zone of fixation adjacent to the dressing that did not proceed apically. The tissue adjoining the fixed zone and down to the apex had the cellular detail of normal pulp and was presumably vital (Figure 17-17). It was suggested that 2% glutaraldehyde, because of its biochemical effects on the pulp, can be used for pulpotomies in primary teeth. Following this initial clinical investigation with glutaraldehyde, many in vitro and in vivo studies began with important implications and findings for its use in pediatric pulp therapy. Dilly and Courts found that glutaraldehyde did not stimulate a significant immune response. 253 Lekka et al. later found that only a minimal amount of glutaraldehyde diffused through the radicular pulp tissue when compared to formocresol. 254 Clinical studies in primary teeth have been conducted by Garcia-Godoy, 255 Fuks et al., 256 and Alacam 257 for periods ranging from 12, 19, and 42 months. Respective success rates were found to be 98, 90.4, and 96%. Root canal obliteration and internal resorption were seen in the radiographs in a small percentage of the cases in Fuks et al. s study. Other studies have investigated various aspects in the use of glutaraldehyde as a pulpotomy medicament such as concentration, ph, time, and method of application as contrasted to the original values when it was first used After several investigations, Ranly et al. concluded that buffering glutaraldehyde, increasing its concentration, and applying it for longer time periods all enhanced the degree of fixation. 261 They suggested that clinical treatment might involve buffered glutaraldehyde at either 4% for 4 minutes or 8% for 2 minutes. Lloyd et al. felt that the tissue becomes more stable with longer application times of 2% glutaraldehyde. 260 Although Ranly and coworkers originally suggested that glutaraldehyde might be incorporated in a ZOE base over a pulpotomy, 261 a later clinical study found a 48.6% rate of failure with this procedure. 262 Hernandez et al. evaluated the clinical and radiographic results of pulpotomies in permanent molars A Figure Glutaraldehyde pulpotomy. A, Section of the root of a primary molar treated with glutaraldehyde 1 month earlier. Note the Schiff-positive homogenous zone (S) in the coronal region. B, Pulp tissue adjacent to the coronal region has dilated veins and absence of inflammatory cells. C, Tissue in the apical region is also free of inflammatory cells. A wide area of new irritational dentin is evident. At 1 year, the collagen concentration increases with mild inflammation. Reproduced with permission from Kopel HM, et al. The effect of gluteraldehyde on primary pulp tissue following coronal amputation. J Dent Child 1980;47:425. medicated with either formocresol or 2% glutaraldehyde. 263 The observations showed a return to a more normal trabecular bone pattern in perialveolar bone after 2 years with the glutaraldehyde compared to the formocresol treatment. The same concerns that related to the systemic absorption of formocresol have been expressed with the use of glutaraldehyde in pulp therapy. Myers et al. demonstrated some systemic absorption with ultimate excretion of 14 C-glutaraldehyde following a 5-minute application of 2% glutaraldehyde to multiple pulpotomy sites in dogs. 264 B C

27 Pediatric Endodontics 887 Ranly et al. also investigated the systemic distribution of 4% infused glutaraldehyde pulpotomies in rats and found only an approximate 25% of the applied dose. These investigators concluded that the use of glutaraldehyde as a pulpotomy agent in humans would be free of any significant toxicity. 265 Astringents Schröder and Granath documented the fact that pulpal hemorrhage control is critical for pulpotomy success. 232 Kouri et al. compared formocresol pulpotomies in primary teeth using epinephrine versus sterile water and cotton pellets for hemorrhage control. After 6- week to 3-month post-treatment periods, histologic and electron microscopic evidence of healing was similar for both groups. Bleeding times for the epinephrine-treated pulps were 50 seconds versus 251 seconds for the sterile water treated pulps. Less extravasated blood occurred with the epinephrine-treated pulps and was limited to the amputation site. No clinical or radiographic failures occurred for either group. 266 Helig et al. compared aluminum chloride versus sterile water in achieving hemostasis prior to medicament placement in calcium hydroxide pulpotomies for primary teeth in humans. They found a 25% radiographic failure rate in the sterile water group versus no radiographic failures with the aluminum chloride group after 9 months. 267 Ferric sulfate has received the most recent attention as a formocresol alternative in pulpotomy choices. This material, when in contact with tissue, forms a ferric ion-protein complex that mechanically occludes capillaries at the pulpal amputation site. The subjacent pulp tissue is then allowed to heal. Landau and Johnson found a more favorable pulpal response to a 15.5% ferric sulfate solution than calcium hydroxide in primate pulpotomies after 60 days. 268 Fei et al. found a combined clinical and radiographic success rate of 96.3% for ferric sulfate pulpotomies versus a 77.8% success rate for diluted formocresol pulpotomies in humans after 12 months. 269 Fuks et al. found a 92.7% success rate with ferric sulfate versus 83.8% with diluted formocresol in primary tooth pulpotomies after a mean post-treatment time of 20.5 months. They noted that these differences were not statistically significant and therefore concluded the success rates to be similar for both groups. 270 Fuks et al. conducted a histologic study of ferric sulfate versus diluted formocresol treated pulps in primate teeth at 4- and 8-week observation periods. Mild inflammation was evident in 58% of the ferric sulfate group versus 48% of the diluted formocresol group. Severe inflammation was noted in 35% of the ferric sulfate group versus 29% of the diluted formocresol group. Abscess and necrosis were noted in 3% of the ferric sulfate group versus 13% of the diluted formocresol group. They concluded that histologic results were similar for both groups and did not compare favorably with previously reported clinical findings of ferric sulfate potential superiority. 271 Cell-Inductive Agents Mineral trioxide aggregate and calcium phosphate cement have already been described with respect to their potential cell-inductive properties in the context of direct pulp-capping techniques. Their use in pulpotomy techniques remains to be substantiated from control studies. Mineral trioxide aggregate was identified as a potentially effective pulpotomy agent in a review of this material with case examples by Abedi and Ingle. 272 Higashi and Okamoto reviewed the use of calcium phosphate ceramics and hydroxyapatite as potential pulpotomy agents. They studied the particle size effects of hydroxyapatite and β-tricalcium phosphate as variables in pulpotomy success as determined by hard tissue formation. Osteodentin and tubular dentin formation occurred around large particles (300 mu) in contrast to small particles (40 mu), which demonstrated pulp tissue inflammation. 273 Yoshiba et al. provided evidence of α-tricalcium phosphate in combination with calcium hydroxide being successful in bridge formation with less local destruction of pulp tissue than with calcium hydroxide alone. 274 Bone morphogenetic proteins have been proposed as potential capping agents in direct pulp-capping and pulpotomy techniques. Bone morphogenetic proteins 2 to 8 belong to TGF-β, that are signaling proteins that regulate cell differentiation. Bone morphogenetic proteins 2 and 4 have been implicated in odontoblastic differentiation. Nakashima demonstrated dentin bridging in dog tooth coronal pulp amputation when the remaining tissue was capped with BMP-2 and BMP-4, along with recombinant human dentin matrix. After a 2-month time interval, tubular dentin and osteodentin were found histologically in response to both BMP types. 177 Fadhavi and Anderson compared freeze-dried bone, calcium hydroxide, and ZOE in primate deciduous tooth pulpotomies with respect to histologic inflammation and clinical/radiopathic pathology. After 6- week and 6-month time periods, vital pulps with moderate inflammation were found in 83.3% of the freezedried bone group. This was in contrast to the calcium hydroxide group, which demonstrated moderate to severe inflammation in 50% of the cases and signs of

28 888 Endodontics partial necrosis in 100%. Dentin bridge formation occurred in 100% of the freeze-dried bone group versus 50% in the calcium hydroxide group. All of the ZOE-treated teeth were necrotic at 6 months. They concluded that freeze-dried bone was superior to calcium hydroxide within the parameters of their study and might have potential as a pulpotomy agent if substantiated by studies in humans. 178 Nonpharmacotherapeutic Pulpotomy Techniques: Controlled Energy Controlled energy in the form of electrosurgical and laser heat application to the pulp stumps at the canal orifice site has been proposed as an alternative to the more traditional pharmacotherapeutic techniques, particularly those using formocresol. Ruemping et al. identified electrosurgical pulpotomy advantages that can be applied to the controlled energy category at large and include (1) quick and efficient, (2) self-limiting, (3) good hemostasis, (4) good visibility of the field, (5) no systemic effects, and (6) sterilization at the site of application. 275 Electrosurgery. Ruemping et al. histologically compared electrosurgery with formocresol in pulpotomy techniques for primate primary and young permanent teeth. They mechanically amputated coronal pulps and then either applied formocresol to the pulp stump or performed momentary electrosurgery, followed by ZOE cement placement. 275 After an 8-week post-treatment period, the histologic appearance for both groups was similar, with no evidence of pulp necrosis or abscess formation. In the electrosurgery group, secondary dentin was deposited along the lateral canal walls, and the apical two-thirds of the pulp revealed a slightly fibrotic to normal appearance. 275 Shaw et al. compared, after 6 months, the histologic effects of electrosurgery with formocresol on the radicular pulp. They found similar success rates of 80% for the formocresol and 84% for the electrosurgical groups according to their histologic criteria. They concluded that neither technique was superior. 276 Conversely, Shulman et al. histologically compared electrosurgery, formocresol, and electrosurgery plus formocresol in primate pulpotomies. 277 They used 14 C-labeled formocresol and performed coronal amputation with electrosurgery subsequent to pulp chamber roof removal. They found more periradicular and furcal pathologic change after 65 days in the electrosurgery group. They also noted that combining the two techniques of electrosurgery and formocresol produced no better results. Both electrosurgical groups were inferior to the formocresol group. 277 Sheller and Morton histologically studied the effects of electrosurgical pulpotomies on the remaining radicular tissue in 11 primary canines at 6-day, 2-week, 8-week, and 13- week post-treatment intervals. Varying degrees of inflammation, edema, and necrosis were seen at all time periods, with the most favorable tissue appearance occurring at the longer intervals. Those teeth judged to be successful demonstrated reparative dentin formation along the lateral aspect of the radicular canal walls but not across the amputation site. They concluded that their results did not support the concept of electrosurgery being less harmful to pulp tissue than conventional pharmacotherapeutic techniques. 278 A form of electrosurgery, known as electrofulguration, has been suggested for pulpotomies in primary teeth. 279 It involves establishing an electrical arc to the targeted tissue without direct contact of the probe, which ideally confines heat to the superficial tissue level. Mack and Dean investigated the electrofulguration pulpotomy technique in 164 primary molars. 279 After a 26-month post-treatment period, they found a 99.4% clinical and radiographic success rate. They felt that this compared favorably with a 93.9% formocresol pulpotomy success rate in a retrospective study by Hicks et al. with a similar protocol. 196,279 Conversely, Fishman et al. compared calcium hydroxide with ZOE when used as a base over electrofulgurated pulp tissue. Although the overall clinical success rate for the entire sample was 77 to 81%, the radiographic success was 57.3% for the electrofulguration plus calcium hydroxide group and 54.6% for the electrofulguration plus ZOE group. 280 Lasers. Application of laser irradiation in vital pulp therapy has been proposed as another alternative to pharmacotherapeutic techniques. Its advantages and disadvantages are the same as for electrosurgery. Adrian reported that irradiation of the buccal tooth surface with the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser produced less pulp damage than the ruby laser with less histologic evidence of coagulation and focal necrosis. 281 Shoji et al. histologically studied the carbon-dioxide laser in the pulpotomy procedure. They noted that the least amount of pulp tissue injury occurred with defocused irradiation with lower power settings and shorter application. More tissue destruction occurred in the defocused mode with higher irradiation power settings. 282 Kato et al. studied the effects of the Nd:YAG laser on pulpotomized rat molars at low (5 watts) and high (15 watts) power settings. At 2 weeks, histologic evidence showed osteodentin covering the amputated pulps with the low power setting and fibrous dentin formation at the orifice wall of the root canal with the high power setting. Normal root

29 Pediatric Endodontics 889 development was observed in all specimens. 283 McGuire et al. compared the Nd:YAG laser with formocresol in permanent tooth pulpotomies in dogs at 6- and 12-week post-treatment periods. No significant differences in radiographic pathology were found between the two groups. Histologically, the frequency of pulpal inflammation was higher for the laser group (29%) at 12 weeks than for the formocresol group (0%). No differences were found with respect to periradicular inflammation and root resorption. 284 Studies on controlled-energy pulpotomy techniques are equivocal as to their effectiveness in reducing posttreatment inflammation when compared to conventional pharmacotherapeutic techniques. Although clinical reports of success exist, more controlled clinical and histologic investigations are needed to address the variables of power settings, application times, continuous versus pulsed modes of application, and degree of heat dissipation in the radicular pulp and surrounding hard tissues. NONVITAL PULP THERAPY IN PRIMARY TEETH: PULPECTOMY The treatment objectives in nonvital pulp therapy for primary teeth are to (1) maintain the tooth free of infection, (2) biomechanically cleanse and obturate the root canals, (3) promote physiologic root resorption, and (4) hold the space for the erupting permanent tooth. The treatment of choice to achieve these objectives is pulpectomy, which involves the removal of necrotic pulp tissue followed by filling the root canals with a resorbable cement. Indications for this procedure include teeth with poor chance of vital pulp treatment success, strategic importance with respect to space maintenance, absence of severe root resorption, absence of surrounding bone loss from infection, and expectation of restorability. Most negative attitudes toward primary teeth complete pulpectomy have been based on the difficulty in cleaning and shaping the bizarre and tortuous canal anatomy of these teeth. 285,286 This was especially true for primary molars with their resorbing and open apices. 287,288 Removal of abscessed primary teeth has been suggested because of their potential to create developmental defects in the underlying permanent successors In spite of these objections, successful root canal obturation of irreversibly inflamed and nonvital primary teeth can be successfully accomplished. Modifications of adult endodontic techniques, however, must be implemented because of the aforementioned anatomic differences between primary and permanent teeth. Marsh and Largent indicated that the goal of the pulpectomy procedure in primary teeth should be to eliminate the bacteria and the contaminated pulp tissue from the canal. 292 In primary teeth, more emphasis is placed on chemical means in conjunction with limited mechanical débridement to disinfect and remove necrotic pulp remnants from the somewhat inaccessible canals rather than conventional shaping of the canals. Complete pulpectomy procedures have been recommended for primary teeth even with evidence of severe chronic inflammation or necrosis in the radicular pulp Resorbable cements such as ZOE and iodoformcontaining pastes have been recommended as canal obturants. Nonresorbable materials such as gutta-percha and silver points are contraindicated as they will not enhance the primary root physiologic resorptive process (Figure 17-18). Rifkin identified criteria for an ideal pulpectomy obturant that include it being (1) resorbable, (2) antiseptic, (3) noninflammatory and nonirritating to the underlying permanent tooth germ, (4) radiopaque, (5) easily inserted, and (6) easily removed. 296 No currently available obturant meets all of these criteria. Owing to primary tooth exfoliation, the standard for long-term pulpectomy success is shorter than for adult endodontics. Primary tooth pulpectomies are successful if the root is (1) firmly attached, (2) remains in function without pain or infection until the permanent successor is ready to erupt, (3) undergoes physiologic resorption, and (4) is free from fistulous tracts. Radiographically, success is judged by the absence of furcation or periradicular lesions and the re-establishment of a normal periodontal ligament. Historical Perspective Sweet described a four- or five-step technique using formocresol for the treatment of pulpless teeth with and without fistulae. 180 A study of pediatric endodontic procedures was reported by Rabinowitz in which nonvital primary molars were treated with a 2- to 3-day application of formocresol, followed by precipitation of silver nitrate and a sealer of ZOE cement into the canals. 297,298 Although he reported a high success rate, his complicated procedure involved a range of 4 to 17 visits, with an average of 5.5 visits for teeth without periradicular involvement and 7.7 visits for those with periradicular involvement. Hobson described pulpectomy techniques for necrotic primary teeth in which the canals were not débrided. Beechwood creosote was used as a disinfectant, usually for 2 weeks, followed by filling the pulp

30 890 Endodontics A B Figure Root canal filling of a pulpless, maxillary primary lateral incisor. A, Carious exposure and pulp death a candidate for endodontic therapy. B, Six months following successful root canal filling with resorbable zinc oxide eugenol cement. Care must be taken not to perforate the apex or overfill and injure the developing permanent tooth bud. Reproduced with permission from Law DB, Lewis TM, Davis JM. An atlas of pedodontics. Philadelphia: WB Saunders; chamber with a ZOE cement. Treatment proved equally successful for teeth with necrotic pulps or vital infected pulps. 299 In treating primary molars, Lewis and Law used conventional endodontics in canal preparation where they instrumented, irrigated with sodium hypochlorite, and dried the canals, which were then medicated for 3 to 7 days with either eugenol, camphorated parachlorophenol, or formocresol. 1 On the second visit, the canals were mechanically prepared with files and filled with one of various resorbable mixtures, such as ZOE cement or ZOE mixed with iodoform crystals (see Figure 17-18). Judd and Kenny advocated a different complete pulpectomy method for deciduous teeth. 300 For vital pulp extirpation, two Hedstroem files, usually size 20, were slid along opposite sides of the canal to entangle pulp tissue. Ideal placement of the files just short of the apex, with two or three rotations, will ensnare the pulp. When withdrawn, the vital pulp will be removed in toto. If the pulp has degenerated, then the canal should be filed with a single No. 20 to allow access for a red No. 1 Lentulo paste filler. 300 After water irrigation and air drying, canals were obturated with a thin mix (viscosity similar to toothpaste) of a fine-grained, nonreinforced ZOE cement (ZOE 2200, Dentsply-Caulk; Milford, Dela.) using a Lentulo spiral paste filler. 300 Gould reported a clinical study of primary teeth in 27 children, age years to years, using a one-appointment technique. 301 In 35 frankly infected primary molars, a cotton pellet of camphorated parachlorophenol was placed in the chamber for 5 minutes after the canals had been débrided with files over two-thirds of their length. Zinc oxide eugenol cement was then pressed into the prepared canals. After 26 months of clinical and radiographic observation, 83% were judged to be therapeutically successful on the basis of no lesions being detected. In asymptomatic necrotic primary teeth, Frigoletto suggested that canals be débrided with a barbed broach, irrigated with sodium hypochlorite, and dried. Canals were then filled with root canal paste using a specially designed pressure syringe. 75 In instances of symptomatic teeth, Cresatin was mixed with the paste.

31 Pediatric Endodontics 891 Starkey has described a one-appointment and multiappointment method of treating cariously involved primary pulp tissue. 91 The one-appointment method is used in cases with vital pulp tissue, in which inflammation extends beyond the coronal pulp and no radiographic evidence of periradicular involvement is present. In these cases, Starkey recommended a partial pulpectomy to remove the coronal aspects of the radicular pulp, controlling hemorrhaging and filling the canals and crown with a creamy mix of ZOE cement. Starkey s multiappointment method was advocated for cases with necrotic pulps and periradicular involvement. 91 At the first appointment, coronal pulp debris is removed, but the canals are not instrumented. A medicament such as formocresol or camphorated monochlorophenol is placed in the pulp chamber and sealed with IRM for 1 week. If the tooth and surrounding gingival tissues are asymptomatic and clinically negative at the second visit, the canals are mechanically cleansed and débrided and then filled with ZOE cement (Figure 17-19). Modifications of these procedures have been described by Cullen, 302 Dugal and Curgon, 303 Goerig and Camp, 304 Kopel, 305 Mathewson and Primosch, 89 and Spedding. 306 It should be noted that some controversy exists with respect to the relative effectiveness of the one-sitting and two-sitting pulpectomy procedures. Coll et al. reported an 80 to 86% success rate with the one-sitting technique. 307 Primosch et al. noted that 60% of US undergraduate dental programs teach the one-sitting technique versus 26% teaching the two-sitting technique. 69 Extension of formocresol use to the pulpectomy technique was a logical sequence. Vander Wall et al. have shown formocresol to be more effective than either camphorated parachlorophenol or Cresatin as a root canal medicament for inhibiting bacterial growth. 308 Several studies have evaluated the clinical and radiographic findings of the pulpectomy procedure for nonvital primary molars and primary anteriors using formocresol. Coll et al. evaluated a one-appointment formocresol pulpectomy technique for nonvital primary molars. After a mean observation period of 70 months, 86.1% were judged successful. 307 They also found that successful pulpectomized primary molars were not over-retained and the successor premolars had a very low incidence of hypoplastic defects. 307 Barr et al., in a radiographic retrospective evaluation of primary molar pulpectomies performed in a private practice with a mean observation period of 40.2 months, found an overall success rate of 85.5%. 309 Noteworthy findings included 88% complete ZOE paste resorption and a 25.8% reduction of preoperative Figure Three-year successful root canal filling of mandibular second primary molar. (Courtesy of Dr. Paul E. Starkey.) The canals have been thoroughly filed and irrigated at the first appointment and medicated with formocresol or camphorated parachlorophenol. At the second appointment, the canals were filled with resorbable zinc oxide eugenol cement. Reproduced with permission from Law DB, Lewis TM, Davis JM. An atlas of pedodontics. Philadelphia: WB Saunders; 1969.

32 892 Endodontics radiolucencies. These clinicians suggested that posterior primary molar pulpectomies have a relatively high success rate in private practice. Coll et al. and Flaitz et al. also evaluated the results of pulpectomy treatment in primary anterior teeth. 310,311 Using clinical and radiographic evaluations, Coll and colleagues completed 27 pulpectomies in primary incisors and found that their 78% success rate did not differ statistically from comparable primary molar rates after a mean of 45 months. 310 Seventy-three percent were considered to have exfoliated normally. These investigators concluded, however, that documented success rates for indirect pulp capping and pulpotomies in primary anterior teeth were higher than for pulpectomies. Flaitz et al. s contrasting study compared 57 pulpotomies versus 87 pulpectomies in primary anterior teeth followed for a mean of 37 months. 311 Based on the final radiographs in the study, treatment was successful in 68.5% of the pulpotomized group of anterior teeth versus 84% of the pulpectomized group. They concluded overall that pulpectomy was a better treatment option for primary incisors even though they may have shown more radiographic pathosis at the time of the diagnosis. Yacobi and Kenny have twice monitored their success rates in vital pulpectomy and immediate ZOE (ZOE 2200, L. D. Caulk Co.; Milford, Dela.) filling. At 6 months, their success rate was comparable to the formocresol results of 89% for anterior teeth and 92% for posterior teeth. 312 At 2 years, reporting on 81 patients and 253 teeth, Payne et al., using ZOE, reported a mean success rate of 83% for anterior teeth and 90% for posterior teeth. They conjectured that the discrepancy in rates between anterior and posterior teeth was related to the final restorations microleakage from composite resin in the anterior regions and stainless crowns in the posterior. 313 They believed this to be a most acceptable alternative method for saving primary teeth while avoiding the compromising effects of the aldehydes. Alternative Pulpectomy Canal Obturants Zinc oxide eugenol cement has been the most frequently used obturant in the pulpectomy technique. Primosch et al. noted that 90% of US pediatric dentistry undergraduate programs teach ZOE as the pulpectomy obturant of choice. 69 Although considered to be resorbable, Coll et al., in a 6-year follow-up of 41 pulpectomized primary molars, found that ZOE particle retention in the gingival sulcus occurred in 8 of 17 patients followed to the time of premolar eruption. 307 Their technique included a 5-minute formocresolblotted paper point treatment of the canals prior to obturation. As previously mentioned, there has been concern about the use of formocresol in any form in pediatric endodontic therapy. Alternative pulpectomy agents have been proposed to improve on the biocompatibility limitations of ZOE and formocresol. Hendry et al. compared calcium hydroxide with ZOE as a pulpectomy obturant in primary teeth of dogs. At 4 weeks post-treatment, canals treated with calcium hydroxide exhibited less inflammation, less pathologic root resorption, and more hard tissue apposition than ZOE and control-treated teeth. 314 Barker and Lockett identified the potential benefits of Kri paste, an iodoform compound, also containing parachlorophenol, camphor, and menthol. The advantages of this material include bactericidal properties and excellent resorbability. Histologically, they found that this material easily resorbed even when extruded beyond the apex of the treated teeth. An ingress of connective tissue was seen in the apical portions of the treated canals. 315 Bactericidal iodoform pastes have been reintroduced as a root canal filling. 245,316,317 Garcia-Godoy obtained a 95.6% success clinically and radiographically with Kri paste during a 24-month period for 43 teeth. 318 It was noted that this paste would resorb within 2 weeks if found in the periradicular or furcation areas. 319 Rifkin reported an 89% clinical and radiographic success rate after 1 year with Kri paste pulpectomies in primary teeth. 296 Holan and Fuks clinically and radiographically compared Kri paste with ZOE in human primary molars after 48 months postoperatively. They found overall success rates of 84% with the Kri paste group versus 65% with the ZOE group. Kri paste was almost twice as successful in primary first molars as ZOE. However, no significant differences between these two agents occurred in primary second molars. Overfills with Kri paste resulted in 79% success versus 41% success with ZOE. They concluded that iodoform-containing paste had a potential advantage over ZOE in the pulpectomy procedure for primary teeth. 319 Treatment Considerations The preceding review demonstrates the varied techniques and successes for mastering pulp therapy for nonvital and irreversibly inflamed primary teeth. Before outlining treatment methods, special considerations, indications, and contraindications must be addressed by the clinician. General Considerations. 1. The patient should be healthy and cooperative. If any systemic disorders are present that would com-

33 Pediatric Endodontics 893 promise a child s responses, the child s physician or medical team should be consulted. 2. Informed consent, with a clear explanation of the procedure to the parents, must be obtained. Dental Considerations. 1. The tooth must be restorable after the root canal treatment. 2. Chronologic and dental age must be evaluated to rule out teeth with eminent exfoliation. 3. Psychological or cosmetic factors (anterior primary teeth) must be considered, which are often more important to the parent than to the child. 4. The number of teeth to be treated and strategic importance to the developing occlusion must be evaluated. 5. Primary molar root anatomy, along with the proximity of the underlying succedaneous tooth, must be evaluated. Indications for a Pulpectomy Procedure. 1. Primary teeth with pulpal inflammation extending beyond the coronal pulp but with roots and alveolar bone free of pathologic resorption 2. Primary teeth with necrotic pulps, minimum root resorption, and minimum bony destruction in the bifurcation area 3. Pulpless primary teeth with sinus tracts 4. Pulpless primary teeth without permanent successors 5. Pulpless primary second molars before the eruption of the permanent first molar 6. Pulpless primary teeth in hemophiliacs 7. Pulpless primary anterior teeth when speech, crowded arches, or esthetics are a factor 8. Pulpless primary teeth next to the line of a palatal cleft 9. Pulpless primary molars supporting orthodontic appliances 10. Pulpless primary molars when arch length is deficient 11. Pulpless primary teeth when space maintainers or continued supervision are not feasible (handicapped or isolated children ) Owing to the isolation of the children involved in its Bureau of Indian Health Affairs, the US Public Health Service has recommended root canal filling of primary teeth, whenever feasible, rather than space maintainers that require lengthy supervision. 320 Contraindications. 1. Teeth with nonrestorable crowns 2. Periradicular involvement extending to the permanent tooth bud 3. Pathologic resorption of at least one-third of the root with a fistulous sinus tract 4. Excessive internal resorption 5. Extensive pulp floor opening into the bifurcation 6. Young patients with systemic illness such as congenital or rheumatic heart disease, hepatitis, or leukemia and children on long-term corticosteroid therapy or those who are immunocompromised 7. Primary teeth with underlying dentigerous or follicular cysts Clinical Procedures: Partial Pulpectomy Partial pulpectomy can be considered an extension of the pulpotomy procedure in that the coronal portion of the radicular pulp is amputated, leaving vital tissue in the canal that is assumed to be healthy. Although discussed in the context of nonvital pulp therapy, technically, it is a vital pulp therapy technique. The decision to implement the partial pulpectomy is made after removing the coronal pulp from the chamber and encountering difficulty with hemorrhage control from the radicular orifice. Hemorrhage control is achieved with endodontic broaches used to remove one-third to one half of the coronal portion of the radicular pulp tissue from the canals. The canals and chamber are irrigated with hydrogen peroxide followed by sodium hypochlorite and then dried with cotton pellets. If hemorrhage is still impossible to control, all remaining radicular pulp tissue is to be removed, and the complete pulpectomy procedure must be implemented. After successful hemorrhage control from the amputated radicular pulp, a formocresol-dampened cotton pellet, squeezed dry, is placed in the pulp chamber for 1 to 5 minutes. The pellet is removed, and a nonreinforced fast-setting ZOE cement is packed with pressure into the chamber and canals. A radiograph is then taken, and if the canals appear to be adequately filled, a stainless steel crown is placed as a permanent restoration (Figure 17-20). Clinic Procedures: Complete Pulpectomy The child with a necrotic primary tooth presents a considerable challenge for the clinician. In some instances, the tooth may be totally asymptomatic from a clinical standpoint. In other instances, the tooth may be acutely or chronically abscessed, mobile and painful, with

34 894 Endodontics Figure Root canal obturation and crown restoration for a pulpless primary molar. At the first appointment, following mechanical and chemical canal débridement, medicament is sealed in place for 1 week. The canal is obturated at the second appointment with resorbable zinc oxide eugenol cement. A, Zinc oxide eugenol cement root canal filling. B, Oxyphosphate of zinc cement. C, Stainless steel crown. swollen periodontal tissues. In the latter case, the child may be apprehensive and irritable, making relief of pain and swelling the highest priority. In cases of nondraining alveolar abscesses and cellulitis from odontogenic origin, antibiotic therapy using first- or second-generation penicillins should be immediately prescribed for a period of 4 to 7 days. Canal instrumentation can then be implemented. The complete pulpectomy procedure involves the following considerations. Under local anesthesia, the pulp chamber is carefully opened with a high-speed bur to relieve any pressure from the infected pulp. A low-speed round bur or a spoon excavator may be used to clean out the pulp chamber, which is then irrigated with sodium hypochlorite. In cases of acute inflammation, a camphorated monochlorophenol-dampened cotton pellet is placed in the coronal chamber as an interim medicament to chemically sterilize the pulp canals. In cases of chronic abscess formation, a formocresol-dampened cotton pellet is generally used as the interim medicament. The chambers are then sealed with a fast-setting ZOE cement, and the tooth may need to be equilibrated to avoid hyperocclusion. At the end of 1 week, if all acute symptoms including pain and soft tissue swelling have resolved, final canal preparation careful enlargement and débridement is completed with Hedstroem files. Canal irrigation is accomplished with hydrogen peroxide and sodium hypochlorite. Tooth length should be carefully determined, and instrumentation should not extend beyond the apex. Fine files, in ultrasonic or sonic endodontic handpieces, with copious irrigation can be considered in this protocol. The ribbon-shaped and tortuous root canals of primary teeth present a time-consuming problem in obtaining adequate obturation. A pressure syringe was developed by Greenberg for filling primary canals. 321 This technique has been described in detail by Spedding 306 and by Krakow et al The material of choice for filling the root canals of pulpectomized primary teeth is pure ZOE, first mixed as a slurry and carried into the canals using either paper points, a syringe, a Jiffy tube, or a lentulo spiral root canal filler. Aylard and Johnson showed that the lentulo was the best overall ZOE root canal filling instrument for curved canals and the pressure syringe technique was best for straight canals. 323 The slurry may be further compressed into the canals by packing the chamber with a stiffer mix of ZOE. After the canals are estimated to be filled to the chamber floor, the chamber itself is filled with a suitable cement such as a reinforced ZOE or a glass ionomer. As previously mentioned, the tooth is prepared for the placement of a stainless steel crown after evaluation of the canal filling by a radiograph. 90 Mack and Halterman described the rationale and technique for an innovative approach to pulpectomy for primary anterior teeth by using a labial entry to the canal instead of the traditional lingual opening. This allows greater ease of instrumentation and provides incorporation of the access chamber in the esthetic labial veneer preparation. Bonded composite resin is used to complete the final esthetic restoration. 324 Clinical Variation: Pulpotomy for Nonvital Primary Teeth Less demanding techniques than the pulpectomy have been reported for treating irreversibly inflamed primary teeth, usually involving the formocresol pulpotomy technique. Ripa recommended that, owing to the anatomy of primary tooth canals, it would be much easier to perform complete débridement in nonvital primary molars using a pulpotomy technique, with appropriate medicaments. 325 Although there is evidence to support such a concept, the consensus is that the pulpotomy technique should be confined to teeth meeting the selection criteria for vital pulp therapy. 326 Velling 327 and Droter 328 reported high degrees of success in nonvital primary molars with a coronal pulpotomy only, using formaldehyde-type medicaments in either one- or two-appointment visits. The final dressing in the coronal pulp chamber was usually a modified ZOE