Assessment of Diffusion of Hydroxyl and Calcium Ions of Root Canal Filling Materials in Primary Teeth

Transcription

1 Scientific Article Assessment of Diffusion of Hydroxyl and Calcium Ions of Root Canal Filling Materials in Primary Teeth Marcos Ximenes, DDS, MD 1 Mariane Cardoso, DDS, MD, PhD 2 Abstract: Purpose: The purpose of this study was to evaluate the diffusion of hydroxyl (OH-) and calcium (Ca+2) of 2 intracanal calcium hydroxide-based medications through the root dentin and cementum of primary teeth. Methods: Forty roots were selected and a single operator instrumented the canals. The irrigation was performed with a 1% sodium hypochlorite solution, and a final irrigation used 17% ethylenediaminetetraacetic acid solution. The teeth were divided into 3 groups: (1) Group 1 (n=15) thickened calcium hydroxide paste blended with propylene glycol paste; (2) Group 2 (n=15) Calen; and (3) Group 3 (n=10) no medication. Diffusion of the OH- ions was determined using a digital ph meter, and diffusion of Ca+2 ions was determined through atomic absorption spectrometry at baseline, 24 hours, 7 days, 15 days, and 30 days later. Results: Two-way analysis of variance and Tukey s test revealed that Group 1 achieved significantly higher ph values (P<.01), followed by Groups 2 and 3. There was a statistically significant difference between groups (P<.01) in the amount of Ca+2 ions released; Group 1 had the highest diffusion values, followed by Group 2, both with peak diffusion at 7 days. Conclusions: Thickened calcium hydroxide paste blended with propylene glycol paste achieved the greatest diffusion of hydroxyl and calcium through the dentin and cementum of primary teeth (Pediatr Dent 2012;34:) Received July 19, 2010 Last Revision September 26, 2010 Accepted October 10, 2010 KEYWORDS: PRIMARY TEETH, TRAUMA, CALCIUM HYDROXIDE, FILLING MATERIALS There is a high prevalence of dental trauma in primary teeth. Epidemiological studies report as much as a 39% frequency among preschoolers. 1 While there are no differences in gender or affected side, the most affected teeth are the maxillary central incisors. 2-4 Consequences of trauma upon the primary tooth are similar to those on the permanent tooth, involving the same structures in one same tissue environment. Thus, therapeutic maneuvers similar to those used for permanent teeth can be applied to primary ones. The temporary nature of the primary tooth does not justify conducting precarious treatments where biologic principles are overlooked or neglected. 5 Calcium hydroxide (Ca(OH) 2 ) has been suggested as an intracanal medication because of its ability to dissociate into hydroxyl (OH - ) and calcium ions (Ca +2 ), resulting in a higher ph in the adjacent medium and inducing mineralized tissue. 6 It has been demonstrated in vitro that the action of Ca(OH) 2 on pathologic root resorptions occurs through the inhibition of the macrophage s adherence capacity, which is the first stage of a phagocytosis process. Thus, Ca(OH) 2 applied to the intracanal or directly on pulpal tissue reduces the inflammatory reaction of periapical and pulpal tissues. 7 Studies conducted on permanent teeth proved that Ca(OH) 2 has the capacity to release OH -, which is diffused through exposed dentin tubules and raises the ph of the root s surface. 8,9 The rise in ph through the release of OH - has a beneficial effect of inhibiting the action of clastic cells on the root surface and 1 Dr. Ximenes is a PhD student in pediatric dentistry and 2 Dr. Cardoso is a professor of pediatric dentistry, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil. Correspond with Dr. Ximenes at marcosximenes@hotmail.com creating a medium that favors the repair of hard tissue. 10 When abundant, Ca +2 participates in the activation of calcium-dependent adenosine triphosphatase. By binding with carbonic gas in the tissue, Ca +2 forms calcium carbonate crystals, which serve as the calcification nucleus, thereby favoring remineralization. 11,12 The purpose of the present study was to evaluate the diffusion of hydroxyl and calcium of 2 intracanal calcium hydroxide-based medications through the root dentin and cementum of primary teeth. Methods This study was approved by the Committee for Ethics in Research in Humans of the Federal University of Santa Catarina, Floria-nópolis, Santa Catarina, Brazil (process no. 051/09). The sample was made up of 40 primary molar roots in with one-third of the root was intact. The specimens were obtained through transverse sectioning of the root 2.0 mm coronal to the cementoenamel junction using a double-face no diamond disk (KG Sorensen, São Paulo, Brazil). The roots were individually analyzed macroscopically using a stereoscopic magnifying glass (20x). Only intact roots with no perforating resorption were included in the sample. The preparation of the entrance of the canal was performed with an Endo-Z bur (21 mm, Dentsply-Maillefer, São Paulo) using a high-speed drill (Silent MS 350 PB, Dabi Atlante, Ribeirão Preto, Brazil). All the roots were in the initial process of physiological resorption, thus presenting apexes with different degrees of resorption. Therefore, to standardize root lengths, the apices were cut at 7 mm using a double-face no diamond disk (KG Sorensen). The apices were then sealed with Super Bonder Gel (Flex Gel, Lacatite Ltda, São Paulo). After the material cured, each canal was individually shaped with first-series no. 20 to 35 files (Dentsply-Maillefer) at a 32 DIFFUSION OF OH - AND CA +2 IN PRIMARY TEETH

2 length of 7 mm using a new set of files for each group. Irrigation was performed with a 1% sodium hypochlorite solution (Miyako, Guarulhos, Brazil), with an average of 2.5 ml of solution in each canal. The canals received a final irrigation of 1 ml of a 17% ethylenediaminetetraacetic acid (EDTA) solution (Biodinâmica, Ibiporã, Brazil) for 3 minutes and were dried with absorbent paper points (Tannari, São Paulo). The specimens were randomly divided into 3 groups, with 15 roots in each experimental group (Groups 1 and 2) and 10 in the control group (Group 3): (1) Group 1 thickened calcium hydroxide paste blended with propylene glycol paste (CaPE); (2) Group 2 Calen paste (SS White, Rio de Janeiro, Brazil); and (3) Group 3 no medication. The roots were cleaned using ultrasound (Ultrasonic Cleaner 1440D, Odonto Brás, Ribeirão Preto, São Paulo, Brazil) with distilled water in 3 5-minute cycles. The roots were further sealed with Super Bonder gel (Flex Gel, Lacatite Ltda), with 1 drop applied to the existing layer in the apex of each root. A layer of nail polish was then applied over the Super Bonder gel for greater impermeability. The CaPE paste was blended with 400 mg of Ca(OH) 2 powder and 0.2 ml of propylene glycol (Officinale, Florianópolis, Brazil), thereby obtaining a thick blend. The paste was inserted with the aid of a lentulo spiral (Dentsply-Maillefer, São Paulo, São Paulo, Brazil) previously cut at 16 mm and calibrated to 1 mm short of the root s length. The Calen paste, composed of 2.5g calcium hydroxide, 0.5g zinc oxide, 0.05 g colophony, and 2mL polyethylene glycol 400 (vehicle)(ss White), was used according to the manufacturer s instructions and inserted into the canal using a carpule syringe with a disposable 27 guage needle calibrated to 1 mm short of the root s length. The needle was introduced into the canal, and the paste was injected using up-and-down movements. Before and after the insertion of the medication into Groups 1 and 2, the roots were individually weighed on a high precision balance (Electronic Balance FA 2104N, Bioprecisa, Rio de Janeiro), thus providing the weight of the medication inside the canal. The average amount of material inserted was g. The material in Groups 1 and 2 was compressed with a cotton ball until there was a 2-mm space 1 mm for the guttapercha (Dentsply-Maillefer) and 1 mm for the first layer of a photopolymerizable compound resin (Opallis, FGM Produtos Odontológicos, Joinville, Brazil). Thereafter, a second layer of composite resin was placed to complete the restoration. In Group 3, the same sealing procedure was performed, but with the canal empty. Using another layer of photopolymerizable compound resin (Opallis), the roots were individually attached to a metal rod fashioned from orthodontic wire (0.7-mm thick and 5-cm long) in the plastic top of the acrylic recipient containing 20 ml of saline solution. The roots were kept at a constant temperature of 37º C and 100% relative humidity throughout the test period. The ph of the medium (saline solution) was determined using a digital ph meter (ML 1010, Hanna Instruments, São Paulo). Readings were performed after 2 minutes of immersion of the electrode in each flask. Measurements were taken at regular intervals in all groups (baseline, 24 hours, 7 days, 15 days, and 30 days), with the temperature and ph of each sample recorded for each reading. After the ph reading, the specimens were then transferred to a new medium containing saline solution, and the previously used solution was stored in a refrigerator at 4 o C until submitted to analysis. Atomic absorption spectrometry was employed for the determination of Ca +2 concentrations in the medium (ContraA 700, Analytic Jena, Jena, Germany). Prior to the analysis, a reading was performed of the saline solution used in the study to determine whether it contained Ca +2, thereby establishing the baseline for the equipment. The amount of Ca +2 and ph were determined for subsequent analysis. The results were obtained with the aid of the statistical program SPSS 10.0 software (SPSS Inc, Chicago, Ill). Two-way analysis of variance (ANOVA) was used to analyze the change in ph and diffusion of Ca +2 in each group throughout the test period. Tukey s test for groups of unequal sizes was employed for each of the criteria and its interactions. Results Figure 1 displays the distribution of mean ph values in the 3 groups over the 4 periods studied. Two-way ANOVA revealed strong statistical significance in the variation in ph among the materials, periods, and their interactions (P<.01). Tukey s test unequal HSD- honestly significant difference) revealed statistically significant differences between groups (P<.01), with the highest mean ph values in Group 1, followed respectively by Groups 2 and 3. The analysis of periods revealed the lowest ph values at 24 hours, regardless of the material used. A statistically significant difference (P<.01) was found between the 24- hour period and other periods (7, 15, and 30 days). No significant differences were found, however, between the 7-, 15-, and 30-day periods, indicating that these periods are equivalent in terms of mean ph. The interactions between materials and Figure 1. Distribution of mean ph values according to group and period analyzed. Figure 2. Mean quantity of calcium ions released (mg/l) in all groups and periods analyzed. DIFFUSION OF OH - AND CA +2 IN PRIMARY TEETH 33

3 periods demonstrate that all values were equivalent in Group 1. In Group 2, the 24-hour period had poorer results than the other periods analyzed. Thus, compared to the Calen paste, the CaPE paste was able to produce higher ph values, even in the initial 24-hour period. The data from the atomic absorption spectrometry analysis of the solutions are expressed as mg/l. Figure 2 displays the mean diffusion of Ca +2 in the periods analyzed. Two-way ANOVA revealed strong statistical significance regarding the amount of Ca +2 for the materials and periods, but not in their interactions, indicating that Ca +2 was not influenced by any interaction between the materials and periods. Tukey s test (unequal HSD) revealed statistically significant differences between groups (P<.01), with the greatest diffusion of Ca +2 in Group 1, followed respectively by Groups 2 and 3. The lowest values occurred at 24 hours and 30 days, regardless of the type of material employed. The diffusion of Ca +2 was equivalent between 7 and 15 days as well as between 15 and 30 days, although with an observed decrease. There was a large amount of Ca +2 released after 24 hours, with a peak at 7 days with both materials and a decrease in values thereafter. The interactions occasionally demonstrated statistical significance in individual comparisons, but the equivalence in the ANOVA demonstrated that these results were explained by the strength of the variables, and no combination of material and period was sufficient to alter the expected behavior regarding the release of Ca +2. Discussion The results of the present investigation, as well as those of previous studies in permanent teeth 9,13 and primary teeth, 13 demonstrate that there is diffusion of OH - and Ca +2 through dentin tubules. This is explained by the fact that the crown and apical portion of the root were sealed, with the only possible passage of ions through the root dentin and cementum. Other studies report different results, however, and demonstrate that Ca(OH) 2 may be inactivated by the buffering capacity of the dentin. 15,16 The removal of the smear layer from the interior of the root canal facilitates the diffusion of ions through the dentin tubules, thereby enhancing the action of the medication Thus, prior to using an intracanal Ca(OH) 2 -based medication, irrigation should be performed with 17% EDTA for 3 minutes to allow greater action of the medication and a better prognosis of the treatment. 9,19,20 Another factor that may affect permeability is the presence of cementum. 10,12,13 A number of in vitro studies on ion diffusion opted for removing the cementum, 10,21 whereas others maintained it. 13,14 In the present investigation and in previous studies, 14,15 the presence of cementum did not impede ion diffusion. Removing the cementum simulates roots that have already begun the process of pathological resorption. In clinical situations, a single tooth always has some areas of the roots covered with cementum and others without cementum. 22 The aim of endodontic treatment with the use of Ca(OH) 2 as the intracanal medication is not only to act on areas with root resorption (absence of cementum), but also to prevent resorption in areas with cementum. For the assessment of OH - and Ca +2 diffusion, the roots remained immersed in saline solution for the time periods established (24 hours, 7 days, 15 days, and 30 days) Unlike in previous studies, 10,13,14,21 the saline solution in which the roots were immersed was replaced on every measurement day to obtain the maximum diffusion of ions without saturating the medium. A similar method was used in 2009 by Duarte et al. 26 The minimal amount of OH - capable of making a medium unviable for bacterial proliferation by neutralizing the acid environment remains unknown. Ideally, one should use a material that releases the greatest possible number of these ions in order to alkalinize the medium. 14 A more acidic medium leads to greater ion diffusion, as there is a tendency toward neutralization. Thus, it may be suggested that the release of these ions in primary teeth would be greater in vivo due to the presence of an acid environment caused by inflammatory processes. Other authors 14 also suggest that diffusion is greater in vivo due to the presence of the apical foramen as well as both physiological and pathological root resorption. The diffusion of ions through the root dentin may be altered by the interaction of the dentin and ions, permeability of the tubules, and characteristics of the vehicle in which the Ca(OH) 2 is contained. 27 In the present study, both medications tested were associated with viscous water-soluble vehicles: propylene glycol in the CaPE paste and polyethylene glycol 400 in the Calen paste. The use of propylene glycol as a vehicle for Ca(OH) 2 has been widely investigated and has proven to be favorable to inducing the dissociation of OH - and Ca +2 and satisfactory diffusion through dentin tubules. 13 Polyethylene glycol 400 is used as a vehicle for endodontic medications due to the fact that it provides a viscous consistency for the formulation, thereby allowing greater permanence and action of the medication in the root canal. 28,29 Studies on OH - diffusion measured through the determination of ph values report greater diffusion with the use of pastes that associate Ca(OH) 2 powder with propylene glycol when compared to nonviscous mediums, such as distilled water, saline solution, and an anesthetic solution. 13,14,26 Likewise, the association of Ca(OH) 2 powder with polyethylene glycol is also reported to be more effective at ion diffusion than nonviscous media. 30,31 In the present study, both groups exhibited constant diffusion of OH -, with the CaPE paste achieving higher mean ph values than the Calen paste at all evaluation times. This may be attributed to the manual blending of the paste, which allowed a greater powder-liquid proportion and directly influenced the diffusion, as reported by other authors. 12,25 The control group, although it contained no intracanal medication, showed a slight increase in the ph and Ca +2. This increase differs from the results found by others authors 32,33 ; in the control group, for example, there was no increase in ph or Ca +2. The explanation of the different results may be due to the different methodologies used. This study used the roots of human primary teeth, where there is a release of OH - and Ca +2 from the dental tissue and dentine plays an important buffer effect. 15,16 The studies conducted by Zmena et al. 32 and Tanomaru et al. 33 used glass tubes instead of roots, which prevents any diffusion of OH - and Ca +2. The low ph values in Group 2 in the first 24 hours demonstrate that the material diffuses few ions in this period. This may be attributed to the paste s viscosity, which reduces solubility and provides a slower dissociation. In 2004, Ferreira et al. 30 describe a similar finding. Regarding other periods, the 2 groups exhibited the same hydroxyl ion diffusion behavior. This finding disagrees with that described by Chamberlain et al. 9 who reported a drop in mean ph values after a period of 21 days in a study 34 DIFFUSION OF OH - AND CA +2 IN PRIMARY TEETH

4 assessing the change in ph on the surface of the roots of permanent teeth filled with Ca(OH) 2. Peak OH - and Ca +2 diffusion occurred at 7 days in Groups 1 and 2. This finding differs from that reported in studies involving permanent teeth, 9,10 which state that a minimum of 14 days is needed for OH - and Ca +2 to penetrate dentin tubules and reach the root s external surface. The diffusion of Ca +2 may be explained by the presence of the viscous vehicle, which provides better contact with the dentin tubules and, consequently, a greater release of ions. The diffusion of Ca +2 was greater in roots treated with the CaPE paste, which corroborates the findings of previous studies carried out on primary 13 and permanent teeth. 10,21 Although Group 2 released a smaller amount of Ca +2, the values were much higher than those in Group 3. Moreover, this paste offers easy insertion due to the fact that it is previously blended by the manufacturer and is injected using a syringe. In this study, all materials tested showed a prolonged effect on the alkaline environment showing high ph values throughout the days analyzed. The diffusion of Ca +2 was also significant. Within the limitations of this experimental design and in vitro study, no definitive conclusions can be drawn. When evaluating the diffusion of Ca +2 and OH - in vivo, one must consider other factors that can have an influence, such as: the presence of the open apex (which was closed in this study); the presence of physiologic and pathologic root resorption (present in most endodontic treatment cases); and the presence of an inflammatory process (which reduces the external ph around the root, providing greater diffusion of ions). The present study s results help establish the best material and length of use of Ca(OH) 2 as an intracanal medication. When treating the roots of a traumatized primary tooth, the use of CaPE (Ca(OH) 2 powder + propylene glycol) is recommended. The action of this medication (diffusion of hydroxyl and calcium ions together) occurs in 7 to 15 days. The maintenance of the material in the canal offers no further benefit in the control of resorption. Thus, after the 7- to 15-day period, the tooth may be filled or the treatment may be repeated in cases in which there is a need for greater Ca(OH) 2 action. Conclusions Based on this study s results, the following conclusions can be made: 1. Hydroxyl and calcium ions in a calcium hydroxide-based medication are diffused through the dentin and cementum of the roots of primary teeth. 2. The CaPE paste achieved better diffusion of these ions, with peak diffusion occurring at 7 days. Acknowledgment The authors wish to thank Sergio Freitas, DDS, MD, PhD (Professor of Biometrics, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil) for conducting this study s statistical analysis. There are no potential conflicts of interest relevant to this article. References 1. Oliveira LB, Marcenes W, Ardenghi TM, Sheiham A, Bonecker M. Traumatic dental injuries and associated factors among Brazilian preschool children. Dental Traumatology 2007; 23, Andreasen JO, Ravn JJ. Epidemiology of traumatic injuries to primary and permanent teeth in a Danish population sample. Int J Oral Surg 1972;1: Robson F, Ramos-Jorge ML, Bendo CB, Vale MP, Paiva SM, Pordeus IA. Prevalence and determining factors of traumatic injuries to primary teeth in preschool children. Dent Traumatol 2009;25: Jorge OK, Moysés SJ, Ferreira EF, Ramos-Jorge ML, Zarzar PMPA. Prevalence and factors associated to dental trauma in infants 1-3 years of age. Dent Traumatol 2009;25: Roberts G, Longhurst P. Oral and Dental Trauma in Children and Adolescents. Oxford, UK: Oxford University Press; 1996: Duarte MA, Demarchi ACO, Yamashita JC, et al. ph and calcium ion release of 2 root-end filling materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;36: Segura JJ, Llamas R, Rubio-Manzanares AJ, Jimenez-Planas A, Guerrero JM, Calvo JR. Calcium hydroxide inhibits substrate adherence capacity of macrophages. J Endod 1997; 23: Tronstad L, Andreasen JO, Hasselgren G, Kristerson L, Riis I. ph changes in dental tissues after root canal filling with calcium hydroxide. J Endod 1981;7: Chamberlain TM, Kirkpatrick TC, Rutledge RE. ph changes in external root surface cavities after calcium hydroxide is placed at 1, 3, and 5 mm short of the radiographic apex. Dent Traumatol 2009;25: Nerwich A, Figdor D, Messer H. ph changes in root dentin over a 4-week period following root canal dressing with calcium hydroxide. J Endod 1993;19: Seux D, Couble ML, Hartmann DJ, Gauthier JP, Magloire H. Odontoblast like cytodifferentiation of human pulp cells in vitro in the presence of a calcium hydroxide containing cement. Arch Oral Biol 1991;36: Estrela C, Sydney GB, Bammann LL, Felippe Jr O. Mechanism of the action of calcium and hydroxyl ions of calcium hydroxide on tissue and bacteria. Braz Dent J 1995;6: Simon ST, Bhat KS, Francis R. Effect of four vehicles on the ph of calcium hydroxide and the release of calcium ion. Oral Surg Oral Méd Oral Pathol Oral Radiol Endod 1995;80: Nunes ACGP, Rocha MJC. Hydroxyl and calcium ions diffusion from endodontic materials through roots of primary teeth: An in vitro study. J Appl Oral Sci 2005;13: Çalt S, Serper A, Ozcelik B, Dalat MD. ph changes and calcium ion diffusion from calcium hydroxide dressing materials through root dentin. J Endod 1999;25: Haapasalo HK, Siren EK, Waltimo TM, Orstavik D, Haapasalo MP. Inactivation of local root canal medicaments by dentine: An in vitro study. Int Endod J 2000;33: Mori GG, Ferreira FC, Batista FR, Godoy AM, Nunes DC. Evaluation of the diffusion capacity of calcium hydroxide pastes through the dentinal tubules. Braz Oral Res 2009; 23: Foster KH, Kulild JC, Weller RN. Effect of smear layer removal on the diffusion of calcium hydroxide through radicular dentin. J Endod 1993;19: DIFFUSION OF OH - AND CA +2 IN PRIMARY TEETH 35

5 19. Garcia-Godoy F, Garcia-Godoy FM. Primary teeth traumatic injuries at a private pediatric dental center. Endod Dent Traumatol 1987;3: Saif S, Carey C, Tordik P, McClanahan S. Effect of irrigants and cementum injury on diffusion of hydroxyl ions through the dentinal tubules. J Endod 2008;34: Heithersay GS. Calcium hydroxide in the treatment of pulpless teeth with associated pathology. J Br Endod Soc 1975;8: Consolaro A. Reabsorções Dentárias nas Especialidades Clínicas. 2 nd ed. Maringá, Paraná, Brazil: Dental Press; 2005: Trope M. Clinical management of the avulsed tooth: Present strategies and future directions. Dent Traumatol 2002;18: Holland R, Otoboni Filho JA, Souza V, Nery MJ, Bernabé PFE, Dezan Jr E. A comparison of one versus two appointment endodontic therapy in dogs teeth with apical periodontitis. J Endod 2003;29: Blomlof L, Lengheden A, Lindskog S. Endodontic infection and calcium hydroxide-treatment. Effects on periodontal healing in mature and immature replanted monkey teeth. J Clin Periodontol 1992;19: Duarte MAH, Midena RZ, Zeferino MA, et al. Evaluation of ph and calcium release of calcium hydroxide pastes containing different substances. J Endod 2009;35: Pashley DH. Dentine permeability theory and practice. In: Spangberg LSW, ed. Experimental Endodontics. Boca Raton, Fla: CRC Press; 1990: Estrela C, Pesce HF. Chemical analysis of the liberation of calcium and hydroxyl ions from calcium hydroxide pastes in connective tissue in the dog: Part I. Braz Dent J 1996;7: Fava LR, Saunders WP. Calcium hydroxide pastes: Classification and clinical indications. Int Endod J 1999;32: Ferreira FBA, Souza PARS, Vale MS, Moraes IG, Granjeiro JM. Evaluation of ph levels and calcium ion release in various calcium hydroxide endodontic dressing. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;97: Camargo CHR, Bernardineli N, Valera MC, et al. Vehicle influence on calcium hydroxide pastes diffusion in human and bovine teeth. Dent Traumatol 2006;22: Zmena O, Pameijer CH, Banegas G. An in vitro study of the ph of three calcium hydroxide dressing materials. Dent Traumatol 2007;23: Tanomaru-Filho M, Chaves Faleiros FB, Saçaki JN, Hungaro Duarte MA, Guerreiro-Tanomaru JM. Evaluation of ph and calcium ion release of root-end filling materials containing calcium hydroxide or mineral trioxide aggregate. J Endod 2009;35: DIFFUSION OF OH - AND CA +2 IN PRIMARY TEETH