The International Journal of Periodontics & Restorative Dentistry

Transcription

1 The International Journal of Periodontics & Restorative Dentistry

2 141 Screw Spreading: Technical Considerations and Case Report Renato Sussumu Nishioka, DDS, PhD, MSc* Alberto Noriyuki Kojima, DDS, PhD, MSc** The spreading system is an alternative technique to the Summers osteotome. The crest expansion technique is a less invasive procedure in which the facial wall expands after the medullary bone is compressed against the cortical wall. It improves the density of the maxillary bone, which allows for greater initial stability of implants. A specific screw instrument, the spreader, achieved a controlled and standardized dilation of the bone horizontally. The use of spreaders to enhance the dental implant site is a highly predictable procedure. (Int J Periodontics Restorative Dent 2011;31: ) * Assistant Professor, Department of Dental Materials and Prosthodontics, Dental School of Sao José dos Campos, São Paulo State University (UNESP), São Paulo, Brazil. ** Graduate Student, Restorative Dentistry Program, Dental School of Sao José dos Campos, UNESP, São Paulo, Brazil. Correspondence to: Dr Alberto Kojima, Department of Dental Materials and Prosthodontics, Av. Eng Franciso José Longo, 777-Jardim São Dimas, São José dos Campos, SP, Brazil ; anorikojima@hotmail.com. The protocol method of preparing a bone site to receive an endosseous implant involves the removal of bone with a graded series of drills (osteotomy). In areas where there is adequate bone volume, a careful surgical procedure with drills of increasing sizes can produce predictable results. However, a maxilla that exhibits extensive atrophy resulting in inadequate bone for the placement of implants often poses a problem for the surgeon. Alveolar resorption following trauma, extraction, or infection has resulted in a ridge form with deficient width or height for dental implant placement. Therefore, dental implants are only a viable treatment option when there is sufficient bone quality and quantity. After tooth loss in the anterior or posterior maxilla, the alveolar ridge decreases as a result of bone atrophy. Bone loss can extend to the alveolar process, leaving only a thin wall of bone. When patients present with inadequate alveolar ridges, the application of implant dentistry could be jeopardized. If bone volume is inadequate, several Volume 31, Number 2, 2011

3 142 Fig 1 Spreading system used in this study (JOTA Swiss Bonetec). surgical techniques may be used to reconstruct the deficient ridge prior to implant placement. The advantages and disadvantages of using local bone grafts from the mandible have been described. 1 6 Several techniques have been described for the placement of dental implants in insufficient bone volume. Ridge augmentation procedures available for implant placement include bone grafting, guided bone regeneration, and bone spreading. The morphology of an osseous defect is an important consideration in choosing an augmentation technique. 7 In a series of articles, Summers 8 11 presented a new approach to graft the maxillary sinus. He used a series of increasingly wider round osteotomes to expand areas in the maxilla both horizontally and vertically. Summers stated that the very nature of this technique improves bone density. Glauser et al 12 reported that the osteotome technique significantly improves the success rate of implants in type 4 bone. This technique is performed in a controlled and atraumatic manner and it allows the alveolar ridge to be augmented apically and laterally through implant site preparation and simultaneous implant placement. This localized bone compaction enhances the implant s primary stability and increases the bone-to-implant contact in the early phase of treatment. 13 Osteotomes are malleted into predetermined implant sites on the alveolar ridge. Such force application and repeated malleting could be disconcerting to the patient. An animal study revealed increased bone-to-implant contact in the early phase after implant treatment, and new bone formation was shown to begin earlier than after conventional implant treatment. 14 The bone spreading technique (BST) is a minimally invasive horizontal augmentation procedure with simultaneous implant placement and is an alternative technique to the Summers osteotome (Fig 1). Modifications to the traditional placement protocol include the use of undersized spreaders. The screw spreader is an innovative design. The main advantage of the crestal expansion technique is that it is a less invasive procedure. The facial wall expands after the medullary bone is compressed against the cortical wall, thus improving the density of the maxillary bone, which allows greater initial implant The International Journal of Periodontics & Restorative Dentistry

4 143 Fig 2 Baseline CT scans obtained with the surgical template in place. stability. A specific screw instrument, the spreader, achieved a controlled and standardized dilatation of bone horizontally. The bone can then be correctly prepared for the subsequent process of implant insertion. Spreaders of increasing diameter are introduced gently and sequentially to expand the implant site. With each spreader, the bone is pushed laterally. The implant should be slightly larger in diameter than the site created by the last spreader. The improved density of the implant site enhances the implant s primary stability. 15 The objective of this case report is to demonstrate a new armamentarium using the BST to greater control and eliminate the possible need for a mallet. Method and materials Before treatment, the patient (55-year-old woman) was screened for preexisting dental problems, and a systemic health analysis was performed. Existing intraoral infections, including those of endodontic and periodontal origin, were treated prior to implant placement. An overall treatment plan was formulated in conjunction with the restorative clinicians. Periapical and panoramic radiographs and a computed tomography (CT) scan were taken (Fig 2). Diagnostic casts, waxups, and surgical templates were also used. Volume 31, Number 2, 2011

5 144 Fig 3 After full-thickness flap reflection, the implant sites were revealed. Fig 4 The patient s existing denture was used as a surgical template for initial drilling. Fig 5 (left) Initial spreader used for implant site preparation (size, A1005). Fig 6 (above) Intraoperative occlusal view after all implants were placed. Surgical technique The patient was instructed to take 2 g amoxicillin or 600 mg clindamycin 1 to 2 hours prior to surgery. After administering 2 carpules of 2% mepivacaine, the crestal incision was performed. A full-thickness flap was raised to expose the alveolar ridge (Fig 3). To secure proper alignment of the implants, a surgical template was used (Fig 4). The proposed implant site was marked clearly using an initial bur at 1,800 rpm under copious irrigation with sterile saline, removing the cortical plate. Use of the initial bur prevented the pilot bur from slipping. Subsequently, the pilot bur produced a subdimensional bone cavity, allowing the drill to penetrate to the desired height so the successive use of a series of spreaders could be used until the desired width was reached (order of diameter and codification of the instruments must be respected) (Fig 5). With the help of the appropriate carrier and, if necessary, with the help of the driver, the spreaders were cautiously screwed into the ridge. After widening the implant cavity in this manner, it was possible to place the suitable implant. Eight self-tapping implants (3.75-mm diameter, 10 to 13 mm long; Conexão Sistema de Prótese) were placed at 20 rpm (Fig 6). Finally, the flaps were sutured in their original positions. Medications prescribed included The International Journal of Periodontics & Restorative Dentistry

6 145 Fig 7 Postoperative CT scans obtained after implant placement. 0.12% chlorhexidine digluconate oral rinse twice a day for 2 weeks, amoxicillin (500 mg four times daily for 7 days), and ibuprofen (600 mg four times daily for 5 days). The patient was not allowed to use her removable prostheses until after sutures were removed 10 to 12 days postoperative. At that time, removable prostheses were adjusted, relined, and placed for cosmetic purposes only. Results Bone rigidity was increased, achieved through bone condensation, and resulted in optimized primary stability (Fig 7). Volume 31, Number 2, 2011

7 146 Discussion Adequate healthy bone volume at the implant site is a prerequisite for the proper long-term osseointegration of implants. The modified technique was developed on a biologically based foundation by the authors in a university practice. The authors suggest that horizontal augmentation using the screwspreading technique be used for patients who have at least 2.5 mm of bone remaining between the facial and lingual walls. Improvements in this technique, including the use of spreaders, appear promising for increasing the bony ridge width. Although there are other screw expansion systems, the use of spreaders to enhance dental implant site development is a highly predictable procedure. The screw-spreading procedure has been developed as an alternative to the Summers osteotome. Osteotomes are malleted into predetermined implant sites on the alveolar ridge. Such force application and repeated malleting can cause disconcerting effects to the patient. Spreaders of increasing diameter are introduced gently and sequentially to expand the implant site. Because neither autogenous nor allogeneic grafting materials are used, there is no concern of leakage of any granular grafting substance. The bone environment is thus created, and a blood clot can form within it. The coagulum will be stabilized and will stay in situ as a natural repair mechanism. In this technique, as an alternative to standard drilling, spreaders were used to gradually expand and compress cancellous bone to improve localized bone density, resulting in optimized primary stability. Summers 8 11 stated that the very nature of the osteotome technique improves bone density in the premolar and molar areas, where type 4 bone is normally found. Adequate primary stabilization of maxillary implants at the time of insertion is considered one of the primary reasons for osseointegration. The use of spreaders was preferred because hand instrumentation facilitated better tactile sensitivity, more precise control, and less heat generation. Therefore, the clinician retains the tactile sensation. The screw-spreader technique seems to be easier to perform, with the possibility of fewer surgical complications. It is important that the clinician be well versed in these various treatment modalities. The protocol outlined in this study was developed to standardize the planning approach for the treatment of insufficient maxillary bone volume to achieve predictable results. The clinical observations presented show no complications or patient discomfort, although the postoperative follow-up period was limited. The authors wanted to rehabilitate patients without implementing advanced surgical techniques, such as ridge augmentation, because they increase treatment duration and costs. 16 The International Journal of Periodontics & Restorative Dentistry

8 147 Conclusion Restoring posterior edentulism with dental implants requires careful treatment planning. This procedure possesses the advantage of being a simple and fast surgical technique. The BST eliminates the possible need for a mallet and has the advantage of minimal postoperative symptoms for the patient. The results of several clinical cases led to the conclusion that the smaller the width of bone, the easier it is for the screw-spreading technique to be performed with a successful outcome. References 1. Collins TA. Onlay bone grafting in combination with Brånemark implants. Oral Maxillofac Surg Clin North Am 1991;3: Jensen J, Sindet-Pedersen S. Autogenous mandibular bone grafts and osseointegrated implants for reconstruction of the severely atrophied maxilla: A preliminary report. J Oral Maxillofac Surg 1991;49: Misch CM, Misch CE. The repair of localized severe ridge defects for implant placement using mandibular bone grafts. Implant Dent 1995;4: Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants 1997;12: Montazem A, Valauri DV, St-Hilaire H, Buchbinder D. The mandibular symphysis as a donor site in maxillofacial bone grafting: A quantitative anatomic study. J Oral Maxillofac Surg 2000;58: Triplett RG, Schow SR. Autologous bone grafts endosseous implants: Complementary techniques. J Oral Maxillofac Surg 1996; 54: Shulman LB. Surgical considerations in implant dentistry. J Dent Educ 1988;52: Summers RB. A new concept in maxillary implant surgery: The osteotome technique. Compendium 1994;15:152, Summers RB. The osteotome technique: Part 2 The ridge expansion osteotomy (REO) procedure. Compendium 1994;15: 422, 424, Summers RB. The osteotome technique: Part 3 Less invasive methods of elevating the sinus floor. Compendium 1994;15: 698, 700, Summers RB. The osteotome technique: Part 4 Future site development. Compendium 1995;11:1090, 1092, , Glauser G, Naef R, Scharer P. The osteotome technique A different method of implant placement in the posterior maxilla. Implantologie 1998;2: Davarpanah M, Martinez H, Tecucianu JF, Hage G, Lazzara R. The modified osteotome technique. Int J Periodontics Restorative Dent 2001;21: Nkenke E, Kloss F, Wiltfang J, et al. Histomorphometric and fluorescence microscopic analysis of bone remodelling after installation of implants using an osteotome technique. Clin Oral Implants Res 2002; 13: Yildirim M, Edelhoff D, Hanisch O, Spiekermann H. The internal sinus lift An adequate alternative to the conventional sinus floor elevation [in German]. Zeitschr Zahnärtzl Implantol 1998;14: Deporter D, Todescan R, Caudy S. Simplifying management of the posterior maxilla using short, porous-surfaced dental implants and simultaneous indirect sinus elevation. Int J Periodontics Restorative Dent 2000;20: Volume 31, Number 2, 2011