International Journal of Periodontics & Restorative Dentistry, 04/2005

Seventeen endosseous titanium implants were placed in completely edentulous jaws of 15 patients. The implants were loaded immediately or after 2 or 6 months, with 100 g orthodontic force. Three weeks later, the implants were removed and histologically analyzed. All of the immediately loaded implants, along with three of the eight that were loaded after 2 months, were lost. The remaining implants were stable until the end of the study. Histologic analysis of the retrieved implants showed bone remodeling in the cortical bone, thickening of the bony trabeculae by new lamellar bone deposition, and microcalli of woven bone or a lattice of woven bone formation around some implants that had been placed in soft bone. Tetracycline labeling revealed an elevated amount of newly formed bone. If further studies prove that a controlled application of orthodontic force, before application of occlusal loading, is able to rapidly enhance the density of soft peri-implant bone, we will have a powerful and precise tool to improve the rate of implant success.

The aim of this prospective longitudinal study of patients treated for generalized aggressive periodontitis (GAP) was the clinical, microbiologic, and radiologic longitudinal evaluation of implants placed into bone regenerated by the guided bone regeneration (GBR) technique. Ten patients with GAP who had lost either one or two maxillary incisors or premolars through periodontal disease and whose alveolar bone was neither high nor wide enough for implant placement were enrolled in the study. GBR was carried out in a two-stage procedure using titanium-reinforced extended polytetrafluoroethylene membranes and titanium screws. No bone graft or bone substitute materials were used. After 6 to 8 months, the membranes and supporting screws were removed, and a total of 15 implants (Nobel Biocare) were placed. The control group comprised 10 periodontally healthy patients who had a total of 11 implants (Nobel Biocare) placed in the maxilla (incisor and premolar region) without GBR because of aplasia, trauma, or endodontic lesions. All patients were examined 2 to 4 weeks before extraction of the nonretainable teeth (baseline) and again immediately after placement of the superstructure. Further examinations were performed within the framework of a 3-month recall schedule over a 3-year period. At each session, clinical parameters (probing pocket depths, bleeding on probing, gingival recession, clinical attachment level, Gingival Index, and Plaque Index) were recorded at teeth and implants, and the composition of the subgingival microflora was determined by dark-field microscopy and DNA probe. Intraoral radiographs were taken for control purposes at baseline, immediately after insertion of the superstructure, and 1 and 3 years later. The GBR technique yielded a horizontal and vertical bone gain of 4.5 to 7.0 mm in the GAP patients. The clinical, microbiologic, and radiologic findings indicated healthy periodontal and periimplant conditions in both patient groups throughout the study. However, a slightly increased attachment loss (0.65 mm) and bone loss (1.78 mm) were recorded at the implants in the regenerated bone after 3 years of loading. The 3-year implant survival rate was 100% in both groups. The possibility of continuous attachment loss and bone loss occurring at teeth and implants in regenerated bone cannot be ruled out in patients treated for aggressive periodontitis. The prognosis for the retention of the teeth and implants is thus open to question.

Part 1 of this series provided the foundation for understanding the nature of densely sintered alumina- and zirconia-based restorations, provided guidelines for case selection, and addressed framework design considerations. This article discusses guidelines for lamination of the densely sintered alumina- and zirconiabased restorations and proper try-in, and examines options for conventional and adhesive luting procedures.

This study presents a clinical, radiographic, laboratory, and histologic/histomorphometric analysis of the use of mandibular block autografts for vertical alveolar ridge augmentation. Twelve patients were included in the study. The autogenous block autografts were fixated at the recipient sites with screws, and a mixture of autogenous bone marrow and inorganic bovine mineral (Bio-Oss) was used at the periphery. At re-entry surgery, all the grafts appeared well incorporated at the recipient sites. Radiographic measurements revealed an average of 5.75 ± 1.29 mm vertical ridge augmentation at 1 month after surgery and 4.75 ± 1.29 mmat 4 to 6 months after surgery. This indicated 17.4% resorption. Laboratory volumetric measurements revealed an average of 0.84 ± 0.34 mL of alveolar ridge augmentation 1 month after surgery and 0.71 ± 0.28 mL at 6 months postoperatively. The resorption rate according to the laboratory volumetric measurements was 15.5%. Linear laboratory measurements revealed 5.92 ± 1.38 mm of vertical ridge augmentation 1 month postoperatively and 4.08 ± 1.01 mmat 4 to 6 months after surgery. Histologic evaluation of the block autografts indicated signs of active remodeling activity in 10 of the 12 specimens. In one case the block graft became exposed and infected, and in another case the block autograft became dislodged during implant placement surgery. Histomorphometric analysis of the peripheral particulate bone indicated bone present at 33.99% ± 8.82% of the graft surface, while 42.43% ± 11.06% of the area was occupied by fibrous tissue and 23.89% ± 9.12% was made up of residual Bio-Oss particles. Residual Bio-Oss particles were in tight contact with newly formed bone along 58.57% ± 15.22% of their perimeter.

This study utilized three-dimensional micro-computed tomography (micro-CT) to evaluate the regenerative response to Bio-Oss Collagen when used alone or in combination with a Bio- Gide bilayer collagen membrane for the treatment of four intrabony defects (5 to 7 mm) around single-rooted teeth. The micro-CT observations are compared to the clinical, radiographic, and histologic results, which have been previously reported. After reflecting a fullthickness flap, thorough degranulation and root planing were accomplished. Bio-Oss Collagen was then used to fill the defects, and in two cases a Bio-Gide membrane was placed over the filled defect. Radiographs, clinical probing depths, and attachment levels were obtained before treatment and immediately preceding en bloc resection of teeth and surrounding tissues 9 months later. A mean pocket depth reduction of 5.75 mmand mean clinical attachment level gain of 5.25 mm were recorded. The histologic evaluation demonstrated the formation of a complete new attachment apparatus with new cementum, periodontal ligament, and alveolar bone at the level of and coronal to the calculus reference notch. Micro-CT evaluation confirmed the histologic results and demonstrated the absence of ankylosis or root resorption for all specimens. This human histologic study demonstrated that Bio-Oss Collagen has the capacity to facilitate regeneration of the periodontal attachment apparatus when placed in intrabony defects. Micro-CT observations confirmed the histologic results and enhanced the three-dimensional understanding of periodontal wound healing. The results indicate that micro-CT may be useful for three-dimensional evaluation of periodontal regenerative procedures.

For reconstruction of an atrophied posterior mandible, different therapeutic options have been proposed, such as autologous bone grafting, guided bone regeneration for vertical ridge augmentation, and inferior alveolar nerve (IAN) mobilization with simultaneous implant placement. The possible dehiscence of soft tissues covering the surgical zone makes the first and second techniques unpredictable. Moreover, two surgical sites are necessary and a long treatment time is required (about 12 months). With IAN mobilization, only one surgical intervention is required and the total treatment time is shorter (about 6 months). However, this technique risks irreversible damage to the IAN, with consequent functional alterations. Current studies have shown extreme variability in the examination of functionality of the neurovascular bundle after its mobilization. This variability can be attributed both to the methodology used for the tests, which evoke subjective answers from the patient, and to the surgical procedure, which is highly dependent on operator technique. Nerve damage can be the result of an overstretched mucoperiosteal flap in the premolar area to achieve optimal visibility of the surgical zone. This article reports a case in which a new surgical approach to IAN mobilization is performed using a specifically engineered device for simplified bone surgery (Mectron Piezosurgery). This device enables the surgeon to cut hard tissue without injuring the soft tissues. Therefore, there is a lower risk of damaging the IAN, and it is possible to reduce overstretching of the mental nerve by creating a smaller bone window and using an apicocoronal inclination of instruments to capture the neurovascular bundle.

In the treatment of patients with severe periodontal disease, it is becoming possible to re-establish a healthy and well-functioning dentition through interdisciplinary dental teamwork. This article presents a case using a resin-bonded splint for stabilizing periodontally compromised mandibular anterior teeth after orthodontic treatment. A 30-year-old woman came to the authors with severe periodontitis, which had resulted in spacing of the anterior teeth and tipping of the posterior teeth. Periodontal-orthodontic treatment was combined with prosthodontic reconstruction, and a resin-bonded splint extending from canine to canine was placed for postorthodontic stabilization of the periodontally compromised teeth. No debonding of the splint occurred, and no further periodontal invasion was found in this case after 4 years of follow-up.

The replacement of incisors with an unfavorable hard and soft tissue environment in the maxilla can be a challenging procedure in terms of esthetic outcome. The present report describes the replacement of two hopeless central incisors by newly developed titanium implants (TE Implant, Straumann) for immediate placement. This type of implant was chosen to compensate for the natural esthetics, which became compromised because of periodontitis and an unusual root anatomy. Both incisors presented with an atypical enamel paraplasia characterized by a circumferential enamel projection in apical direction. The consequence was a markedly reduced surface for periodontal attachment. Two weeks after implant placement, two acrylic resin crowns were cemented onto the new temporary titaniumabutments. Five months later, the definitive prosthetic restoration was processed by porcelain pressed onto galvanic-cap crowns, which were cemented to standard wide-neck abutments. Control radiographs showed uneventful healing.

To achieve long-term success with an implant-retained overdenture, application of force in the path of insertion of the prosthesis has been recommended. This implies that the retentive matrices and the implants are positioned parallel to each other and to the path of insertion of the prosthesis. This article describes a technique for the fabrication of a surgical template for an implant-retained overdenture in the mandible. Adherence to the guidelines proposed in this article will lead to optimal implant placement in a consistent and repeatable manner.