Impact of rhBMP-2 on regeneration of buccal alveolar defects during the osseointegration of transgingival inserted implants.

OBJECTIVE: New approaches to enhance vertical bone regeneration in clinically relevant implant models are needed. Therefore, we analyzed the impact of recombinant human bone morphogenic protein 2 (rhBMP-2) on the healing of large buccal alveolar defects during osseointegration of transgingivally inserted implants. STUDY DESIGN: Twenty-four dental implants were inserted transgingivally in the mandibles of 6 labrador/golden retriever cross-bred dogs. Before implantation, a standardized buccal bone defect was created and refilled with either calcium phosphate as a carrier containing rhBMP-2 or calcium phosphate alone. Either ceramic abutments that enabled immediate implant loading or healing distance collars to prevent loading were mounted. Sixteen weeks after intervention, bone implant units were analyzed by radiofrequency analysis and histomorphometry. RESULTS: In total, 14 implants (58.3%) were available for further analysis. The mean depth of the bone defects, the gain of regenerated bone, the vertical osseointegration of the implants, and the bone-to-implant contact in the newly formed bone were slightly greater in the rhBMP-2-containing samples. In contrast, the osseointegration in the preexisting bone was even superior within the non-rhBMP-2-treated specimen. However no differences were statistically significant. CONCLUSIONS: When rhBMP-2-conducted bone regeneration was compared with control samples, no significant differences of newly formed bone were found at the bone-implant interface. The amounts of rhBMP-2 applied do not seem suitable to enhance implant osseointegration in large buccal defects.

Purely cancellous vs. corticocancellous bone in sinus floor augmentation with autogenous iliac crest: a prospective clinical trial.

OBJECTIVES: Among the different graft materials being applied in sinus elevation surgery autogenous bone, especially from the iliac crest, is considered to be the graft of choice. The goal of this prospective study was to investigate whether purely cancellous transplants of this donor site lead to significantly better results regarding bone quantity and quality when compared to corticocancellous iliac bone grafts. MATERIAL AND METHODS: Fifteen patients suffering from extreme maxillary atrophy underwent bilateral sinus floor augmentation with grafts from the iliac crest consisting of purely cancellous bone (PCB) for the right side and a mixture of 50% cancellous and 50% cortical bone for the left side, respectively. Bone samples that were taken during implant insertion were examined histologically for semiquantitative assessment. In addition, bone density was measured histomorphometrically. Data were statistically analyzed by a repeated measures analysis of covariance model and post hoc paired t-tests as well as Pearson's correlation analysis. RESULTS: Semiquantitative analysis of bone quality resulted in comparable results for both graft preparations while bone density was significantly higher in the PCB group. Without consideration of the different transplant groups, there was neither a significant correlation between patients' age and bone density nor bone quality. Differences between the genders could not be observed either. CONCLUSIONS: Because of better bone density, the PCB graft from the iliac crest remains our gold standard. Even in elderly patients, autogenous grafts can be utilized without losses in the properties of the resulting bone.

Clinical behavior of zirconia-based fixed partial dentures made of DC-Zirkon: 3-year results.

PURPOSE: The aim of this prospective study was to evaluate the clinical performance of anterior and posterior fixed partial dentures (FPDs) with frameworks made using DC-Zirkon after a mean observation time of 3 years. MATERIALS AND METHODS: Forty-six patients with 1 to 3 missing anterior or posterior teeth were included in this study. All abutment teeth were prepared for full crowns with a chamfer preparation of 0.6 to 0.8 mm. The zirconia frameworks were produced with the Precident DCS system and veneered with veneering porcelain (Vita D). A self-curing resin cement was used for the anterior FPDs and a conventional zinc oxide phosphate cement was used for the posterior FPDs. RESULTS: Fifteen anterior FPDs and 50 posterior FPDs were recalled at least once a year after cementation. The mean observation period was 38 (+/- 18.0) months for the anterior FPDs and 37 (+/- 15.5) months for the posterior FPDs. Within the observation time, no remakes were necessary, but in 4 cases a small chipping of the veneering material occurred in the posterior region. Two FPDs were recemented after decementation, and 3 teeth needed endodontic treatment. No negative influences at the gingival margin were observed. CONCLUSIONS: Within the mean observation time of 3 years, zirconia-based FPDs demonstrated a sufficient success rate under clinical conditions. However, special attention should be paid to designing the zirconia framework to ensure a sufficient veneering layer thickness with a range between 1 to 2 mm.

Survival and complication rates of combined tooth-implant-supported fixed and removable partial dentures.

PURPOSE: The aim of this study was to assess and compare clinical outcome results of tooth-implant-supported fixed and removable partial dentures in a selected population group of partially edentulous patients. Biological and technical complications were recorded and reviewed. MATERIALS AND METHODS: A retrospective analysis of the dental charts of 224 patients (174 men, 50 women) with a mean age of 51.3 years was carried out. The evaluation included details regarding the survival and technical complications of the prescribed prostheses, as well as the biological and technical complications associated with both types of abutments used, ie, teeth and implants. RESULTS: A total of 229 prostheses were supported by 459 implants and 449 teeth. They were monitored for a period of 2 to 10 years (median follow-up time: 6.7 years). At the end of the different observation periods, 14% of the tooth-implant-supported prostheses had undergone technical modifications, with no statistical difference in the occurrence of technical complications between the 2 types of prosthesis. Three of the functionally loaded implants were removed, while 23 abutment teeth were lost (15 had undergone endodontic treatment). Abutment teeth with a reduced attachment level after prosthesis insertion were significantly affected by biological complications (P = .04). CONCLUSIONS: The survival data for both types of prosthesis were comparable to prostheses supported solely by implants. There was no difference in the complication rate between primary splinting (fixed) and secondary splinting with telescopic systems (removable). A greater risk of biological complications was recorded for endodontically treated abutments or teeth with a reduced attachment level.

[Hydroxyapatite bone substitute (Ostim) in sinus floor elevation. Maxillary sinus floor augmentation: bone regeneration by means of a nanocrystalline in-phase hydroxyapatite (Ostim)]. / Hydroxylapatit-Knochenersatzmaterial (Ostim) bei der Sinusbodenelevation. Sinusbodenelevation: Knochenregeneration mittels eines nanokristallinen, phasenreinen Hydroxylapatits (Ostim).

The range of bone regeneration materials suitable for maxillar bone augmentation has increased steadily in the past few years and there is now a wide variety of materials being used. In the present case report, we analyzed the state of bone regeneration after sinus floor augmentation using a nanocrystalline in-phase synthetic anorganic hydroxyapatite bone grafting material (Ostim). A 60-year-old female patient underwent maxillary sinus floor elevation and the cavity was filled with Ostim three years before. Actually, she presented herself with loosening of the dental implant at position 17, as a result of parafunction. At the time of the insertion of a second implant at position 17, bone samples were taken by using a trepan drilling device from the previously augmented area. These samples were analyzed histologically to determine the extent of bone remodeling around the deposits of Ostim. We found that the Ostim deposits were surrounded largely by woven bone and, in parts, by lamellar bone and had facilitated osteoconductive bone regeneration. The adjacent implant, at position 16, which beared a crown exposed to proper biting forces without parafunction, showed proper clinical and radiological characteristics of complete and firm integration into the area which was also filled with Ostim three years ago. We conclude that the use of the nanocrystalline hydroxyapatite Ostim with its stable volume properties appears to be suitable for maxillary sinus floor augmentation. Furthermore, we even found osteoconductive bone regeneration under Ostim near the site of the loosened implant.

Bone reconstruction following implantation of rhBMP-2 and guided bone regeneration in canine alveolar ridge defects.

BACKGROUND: Alveolar ridge aberrations commonly require bone augmentation procedures for optimal placement of endosseous dental implants. The objective of this study was to evaluate local bone formation following implantation of recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier with or without provisions for guided bone regeneration (GBR) as potential treatment modalities for alveolar augmentation. METHODS: Surgically induced, large, mandibular alveolar ridge saddle-type defects (2 defects/jaw quadrant) in seven young adult Hound dogs were assigned to receive rhBMP-2/ACS, rhBMP-2/ACS combined with GBR (rhBMP-2/GBR), GBR, and surgery controls. The animals were euthanized at 12 weeks post-surgery when block sections of the defect sites were collected for histologic analysis. RESULTS: Clinical complications included swelling for sites receiving rhBMP-2 and wound failure with exposure of the barrier device for sites receiving GBR (4/6) or rhBMP-2/GBR (3/7). The radiographic evaluation showed substantial bone fill for sites receiving rhBMP-2/ACS, rhBMP-2/GBR, and GBR. In particular, sites receiving rhBMP-2/GBR presented with seroma-like radiolucencies. The surgery control exhibited moderate bone fill. To evaluate the biologic potential of the specific protocols, sites exhibiting wound failure were excluded from the histometric analysis. Sites receiving rhBMP-2/ACS or rhBMP-2/GBR exhibited bone fill averaging 101%. Bone fill averaged 92% and 60%, respectively, for sites receiving GBR and surgery controls. Bone density ranged from 50% to 57% for sites receiving rhBMP-2/ACS, GBR, or surgery controls. Bone density for sites receiving rhBMP-2/GBR averaged 34% largely due to seroma formation encompassing 13% to 97% of the sites. CONCLUSION: rhBMP-2/ACS appears to be an effective alternative to GBR in the reconstruction of advanced alveolar ridge defects. Combining rhBMP-2/ACS with GBR appears to be of limited value due to the potential for wound failure or persistent seromas.

Lifetime of alumina- and zirconia ceramics used for crown and bridge restorations.

The lifetime of a ceramic is dependent on the presence of incidental cracks and their gradual propagation under the conditions of the oral cavity. The objective of this study was to examine the long-term strength of glass-infiltrated alumina- and various zirconia ceramics currently used in CAD/CAM systems to manufacture crown and bridge frameworks. Fracture mechanics were applied to determine characteristic strength (sigma(omicron)), Weibull modulus (m), fracture toughness (K(Ic)), and the subcritical crack growth parameters n and B. Based on these parameters, lifetime diagrams were generated which allowed the evaluation of the long-term behavior. The results showed that in a moist environment, the glass-infiltrated alumina- and some zirconia ceramics have a high susceptibility to subcritical crack growth. Zirconia ceramics with an alumina oxide content of 0.25 wt %, however, exhibited the highest initial and most favorable long-term strength, and should therefore be suitable for crown and bridge restorations.

[PVD-layering for increased retention of glass fibre reinforced endodontic posts]. / PVD-beschichtung für verbesserte Retention glasfaserverstärkter Wurzelkanalstifte.

For esthetical and biomechanical reasons root canal posts made of fibre-reinforced composite (FRC) have gained an important role in clinical application. Additionally, in contrast to metal or ceramic posts, FRC-posts offer the option of removal. Prior to adhesive placement of FRC-posts the root canal dentin of the non vital tooth and the post surface have to be preconditioned. Up to now the post preconditioning has to be proceeded in the chair side technique. This leads to an additional time expense in the clinical treatment schedule. Also a certain risk of errors in application during chair side conditioning procedure is of concern. Modern PVD-technologies can help to make the treatment by the manufacturer well in advance of the clinical use more efficient and reliable, as well as saving clinicians valuable chair-time. For this reason the apical surfaces of the posts were intensively cleaned and activated, PVD-layered and coated by a conserving transparent layer. This coating has the meaning to protect the surface against environmental contamination and allows the try-in of the posts without any risk of damage of the preconditioned surface. To prove the stability of the layer system under simulated clinical conditions pull out tests after 180 days'storage in physiological saline solution have been performed.

Survival and complication rates of combined tooth-implant-supported fixed partial dentures.

OBJECTIVES: The objective of this study has been to review the incidence of biological and technical complications in case of tooth-implant-supported fixed partial denture (FPD) treatments on the basis of survival data regarding clinical cases. MATERIAL AND METHODS: Based on the treatment documentations of a Bundeswehr dental clinic (Cologne-Wahn German Air Force Garrison), the medical charts of 83 patients with tooth-implant-supported FPDs were completely recorded. The median follow-up time was 4.73 (time range: 2.2-8.3) years. In the process, survival curves according to Kaplan and Meier were applied in addition to frequency counts. RESULTS: A total of 84 tooth-implant (83 patients) connected prostheses were followed (132 abutment teeth, 142 implant abutments (Branemark, Straumann). FPDs: the time-dependent illustration reveals that after 5 years, as many as 10% of the tooth-implant-supported FPDs already had to be subjected to a technical modification (renewal (n=2), reintegration (n=4), veneer fracture (n=5), fracture of frame (n=2)). In contrast to non-rigid connection of teeth and implants, technical modification measures were rarely required in case of tooth-implant-supported FPDs with a rigid connection. There was no statistical difference between technical complications and the used implant system. Abutment teeth and implants: during the observation period, none of the functionally loaded implants (n=142) had to be removed. Three of the overall 132 abutment teeth were lost because of periodontal inflammation. The time-dependent illustration reveals, that after 5 years as many as 8% of the abutment teeth already required corresponding therapeutic measures (periodontal treatment (5%), filling therapy (2.5%), endodontic treatment (0.5%)). After as few as 3 years, the connection related complications of implant abutments (abutment or occlusal screw loosening, loss of cementation) already had to be corrected in approximately 8% of the cases. In the utilization period there was no screw or abutment fracture. CONCLUSION: Technical complications of implant-supported FPDs are dependent on the different bridge configurations. When using rigid functional connections, similarly favourable values will be achieved as in case of solely implant-supported FPDs. In this study other characteristics like different fixation systems (screwed vs. cemented) or various implant systems had no significant effect to the rate of technical complications.

Excelência restauradora em cerâmica pura: visão geral / All-ceramic restorative achievements: an overview

A introdução de materiais totalmente cerâmicos à base de sílica e das técnicas de cimentação adesiva possibilitou preparos inovadores e estética excepcional no campo da odontologia restauradora. Apesar dos constantes aperfeiçoamentos das propriedades ópticas e mecânicas, as restaurações de cerâmica vítreas ainda estão bastante limitadas a restaurações unitárias, bem como a próteses fixas de espaço protético pequeno, com determinadas restrições, na zona estética. Assim como as propriedades mecânicas das novas cerâmicas de óxido de alta resistência, tais como as cerâmicas de dióxido de zircônia estabilizadas parcialmente, a confiabilidade delas a longo prazo também melhorou significativa-mente, facilitando a aplicação clínica de retentores radiculares de cerâmica pura, de pilares de implante, bem como de infra-estruturas para próteses fixas, aplicáveis também na região posterior. Tendo em vista a variedade sempre crescente de sistemas totalmente cerâmicos, este artigo fornece conceitos de tratamento baseados em estudos clínicos, incluindo a seleção correta do material, dependendo da situação clínica.

Randomized multicenter comparison of 2 IMZ and 4 TPS screw implants supporting bar-retained overdentures in 425 edentulous mandibles.

PURPOSE: Two treatment concepts for implant-supported bar retention of mandibular overdentures-2 intramobile cylinder (IMZ) implants and a Dolder bar and 4 titanium plasma-sprayed (TPS) screw implants and an angulated bar-were compared in a randomized controlled clinical trial with respect to postprosthetic efficacy and safety. MATERIALS AND METHODS: Four hundred twenty-five patients with edentulous mandibles were enrolled; 212 were randomized to TPS implants (control group) and 213 to IMZ implants (test group). Endpoints were occurrences of postprosthetic integration deficiency (ID), functional deficiency (FD), and complications. The trial was sized to detect a 10% difference in 5-year ID-free postprosthetic system lifetime with a power of 80%. RESULTS: With 340 protocol-completed cases, the trial achieved its predetermined power. The 2 systems did not show statistically significant differences in occurrences of postprosthetic ID and FD; 5-year occurrence-free postprosthetic system lifetime probabilities were estimated as 42.5% with IMZ and 42.8% with TPS, for ID; and as 82.6% with IMZ and 87.2% with TPS, for FD. However, at 3 to 6 months after surgery, mean Periotest values were significantly higher (P = .0001 without adjustment) with IMZ implants (5.6, SD 4.2) than with TPS implants (0.8, SD 4.3). TPS implants showed a higher incidence of inflammation and recession, while IMZ implants had a higher incidence of implant fracture after functional loading. DISCUSSION: The system-wise approach overcomes potential bias with implant-wise analyses. A combination of radiographic and clinical criteria distinguishes between desirable integration and functional anchorage. The in situ survival rates at 5 years in this study (95% for IMZ, 92% for TPS) match rates reported in the literature. CONCLUSION: This study demonstrated equivalent efficacy of 2 IMZ cylinders and 4 TPS screws in implant-supported, bar-retained mandibular overdentures and indicated a higher rate of complications with the TPS screw implants.

Effect of recombinant human bone morphogenetic protein-2 in dehiscence defects with non-submerged immediate implants: an experimental study in Cynomolgus monkeys.

BACKGROUND: Alveolar ridge aberrations commonly compromise optimal dental implant installation. To offset any variance between an aberrant alveolar ridge and prosthetic designs, bone augmentation procedures become necessary. The objective of this study was to evaluate bone formation and osseointegration at alveolar dehiscence defects following augmentation of the defect site with recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge carrier (ACS) at dental implant installation including transmucosal positioning of the dental implant. METHODS: Four adult male Cynomolgus monkeys received dental implants in contralateral extraction socket sites with surgically created 6 x 4 mm buccal dehiscence defects following elevation of mucoperiosteal flaps. Contralateral sites received rhBMP-2/ACS (rhBMP-2 at 1.5 mg/ml; 0.1 mg/defect) or served as sham-surgery controls. The flaps were adapted and sutured around the healing abutments leaving the implants in a transmucosal position. The animals were sacrificed at 16 weeks postsurgery and block sections of the implant sites were harvested and prepared for histometric analysis. RESULTS: One dental implant from each treatment group failed to osseointegrate. Another 3 dental implants (sham-surgery controls) failed to osseointegrate with newly-formed bone in the defect area. Thus, 7 of 8 defect sites (4/4 animals) receiving rhBMP-2/ACS compared to 4 of 8 sites (2/4 animals) receiving sham-surgery exhibited evidence of osseointegration with newly formed bone in the defect area. Mean +/- SD defect height amounted to 5.3 +/- 0.2 and 5.4 +/- 0.1 mm for the rhBMP-2/ACS and sham-surgery sites, respectively. Vertical bone gain in rhBMP-2/ACS treated defects (3.9 +/- 0.3 mm) did not differ significantly from that in the sham-surgery control (3.7 +/- 0.4 mm; P > 0.05; paired t-test, N = 4). There were also no significant differences noted for coronal bone-implant contact (3.0 +/- 0.6 versus 3.6 +/- 0.5 mm), and bone-implant contact within the defect site (28.5% +/- 15.1% versus 27.4% +/- 31.7%) and within resident bone (46.9% +/- 26.8% versus 47.8% +/- 39.4%) for the rhBMP-2/ACS and control sites, respectively. CONCLUSIONS: The observations in this study point to a substantial native osteogenic potential of the alveolar process that has previously not been explored and show that surgical reentry observations of new bone formation may not necessarily indicate that osseointegration has occurred. Bone formation in control defects was substantially greater than predicted, limiting the value of adding an osteoinductive biologic construct.

Long-term functional loading of dental implants in rhBMP-2 induced bone. A histologic study in the canine ridge augmentation model.

Osseointegration [direct bone-implant contact (BIC)] is a primary goal following installation of endosseous dental implants. Such bone contact provides stability for the dental implant over time. The objective of this study was to evaluate bone formation and BIC at long-term, functionally loaded, endosseous dental implants placed into bone induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier. Mandibular, saddle-type, alveolar ridge defects (approximately 15 x 10 x 10 mm), two per jaw quadrant, were surgically induced in each of six young adult American fox hounds. The defects were immediately implanted with rhBMP-2/ACS. Two defects per animal additionally received a nonresorbable expanded polytetrafluoroethylene (ePTFE) membrane or a bioresorbable polyglycolide fiber membrane. Healing was allowed to progress for 3 months, when the ePTFE membrane was removed, and machined, threaded, titanium dental implants were installed into the rhBMP-2/ACS induced bone and into the adjacent resident bone. At 4 months of osseointegration, the implants were exposed to receive abutments and prosthetic treatment (two- or three-unit bridges). Some implants were removed for histologic analysis. The remainder of implants were exposed to functional loading for 12 months at which time the animals were killed for histometric analysis. One animal died prematurely due to kidney failure unrelated to the experimental protocol and was not included in the analysis. The 12-month block sections from a second animal were lost in the histological processing. Four sites receiving rhBMP-2/ACS and ePTFE or resorbable membranes experienced wound failure and membrane exposure, and subsequently exhibited limited bone formation. Defects without wound failure filled to contour with the adjacent alveolar bone. The newly formed bone exhibited features of the resident bone with a re-established cortex; however, it commonly included radiolucent areas that resolved over time. Dental implants block biopsied at 4 months exhibited limited, if any, crestal resorption, whereas those exposed to functional loading for 12 months exhibited some crestal resorption. Implants biopsied at 4 months exhibited a mean (+/- SD) BIC of 40.6 +/- 8.2% in rhBMP-2/ACS induced bone vs. 52.7 +/- 11.4% in resident bone. Dental implants exposed to 12 months of functional loading exhibited a mean BIC of 51.7 +/- 7.1% in rhBMP-2/ACS induced bone vs. 74.7 +/- 7.0% in resident bone. There were no significant differences between dental implants placed into rhBMP-2/ACS induced bone and resident bone for any parameter at any observation interval. In conclusion, rhBMP-2/ACS-induced bone allows installation, osseointegration, and long-term functional loading of machined, threaded, titanium dental implants in dogs.

Randomized multicenter comparison of two coatings of intramobile cylinder implants in 313 partially edentulous mandibles followed up for 5 years.

Intramobile cylinder (IMZ) implants with either of two coatings, hydroxyapatite (HA) or titanium plasma-flame (TPF), as distal abutments for combined tooth implant-supported restorations, were compared in 313 partially edentulous mandibles with respect to postprosthetical failure patterns and complication frequencies in a randomized multicenter clinical trial. Within the treatment protocols, the two coatings do not show evidence of different efficacy with respect to occurrence of postprosthetical integration deficiency (ID) or functional deficiency (FD). Statistical equivalence for an absolute effect of +/-15% in event-free survival could only be demonstrated for FD, not for ID, however. Intent-to-treat and per-protocol population analyses gave consistent results. Hazards of occurrence of ID and FD, adjusted for years of follow-up, were estimated for ID as 7% per year (95%CI 4-10% per year) with HA and 5% per year (95%CI 3-7% per year) with TPF, and for FD as 5% per year (95%CI 3-7% per year) with HA and 4% per year (95%CI 2-6% per year) with TPF. The 5-year cumulative success rates for no ID were 69.5% (95%CI 58-81%) with HA and 82.2% (95%CI 74-91%) with TPF. With respect to frequencies of complications, there was no relevant statistically significant difference between the two coatings.

A review of esthetic pontic design options.

Advances in the field of restorative materials allow a lost tooth to be replaced by artificial tooth structure that is virtually indiscernible from the original. However, in fixed partial dentures the standards for the pontic area and the adjacent soft tissue in the maxillary anterior region have increased in particular. The pontic design in this region is primarily influenced by esthetic and phonetic considerations. Local defects of the alveolar ridge often complicate restorative measures. Treatment methods proposed to solve this problem involve modification of the pontic design and pretreatment of the recipient site for the pontic. This article reviews the different clinical and technical options that are available for designing esthetic and functional pontics for the anterior region.