A Partial Palatal Coverage Overdenture Retained by Zygomatic Implants.

Prosthodontic rehabilitation of an atrophic edentulous maxilla can be challenging and is further complicated when multiple risk factors are present. Fixed prostheses require multiple implants for support/retention organized in biomechanically favorable positions in order to afford a good prognosis. Such suitable implant arrangements in an atrophic edentulous ridge can often be difficult to achieve. Removable prostheses require fewer implants for a favorable prognosis and can furthermore take advantage of the additional anatomical structures for support/retention. This clinical treatment will describe the fabrication of a partial palatal coverage overdenture retained by zygomatic implants.

Effect of 3- and 4-mm interimplant distances on the height of interimplant bone crest: a histomorphometric evaluation measured on bone level dental implants in minipig.

PURPOSE: To analyze crestal bone loss changes that may affect the gingival height around an implant and bone loss in interproximal areas. When implants are placed adjacent to one another, interimplant bone loss around 1 implant may combine with the implant bone loss around the adjacent implant to affect the crestal bone loss interproximally. MATERIALS AND METHODS: The primary objective of this study was to evaluate histologically and histomorphometrically the effect that this implant design with a horizontally displaced implant-abutment junction has on the height of the crest of bone, between adjacent implants separated by 2 different distances: 4 mm and 3 mm. A secondary objective was to evaluate the percentage of bone-to-implant contact, interproximal soft tissue height, location of the junctional epithelium, and length of connective tissue contact to abutment and/or implant, for the 2 different distances. RESULTS: Results showed that the interproximal bone loss measured from the edge of the implant platform to the bone crest was not different for interimplant distances of 4 or 3 mm. In addition, the secondary objective parameters also demonstrated similar results between the 2 interimplant distances. CONCLUSION: This study showed that interimplant bone levels can usually be maintained at similar levels for 4- and 3-mm distances during at least 2 months.

Radiological and micro-computed tomography analysis of the bone at dental implants inserted 2, 3 and 4 mm apart in a minipig model with platform switching incorporated.

BACKGROUND: The purpose of this study was to assess the effect of inter-implant distance on interproximal bone utilizing platform switching. Analysis of interproximal bone usually depends on traditional two-dimensional radiographic assessment. Although there has been increased reliability of current techniques, there has been an inability to track bone level changes over time and in three dimensions. Micro-CT has provided three-dimensional imaging that can be used in conjunction with traditional two-dimensional radiographic techniques. METHODS: This study was performed on 24 female minipigs. Twelve animals received three implants with an inter-implant distance of 3 mm on one side of the mandible and another three implants on the contra-lateral side, where the implants were placed 2 mm apart creating a split mouth design. Twelve other animals received three implants with an inter-implant distance of 3 mm on one side of the mandible and another three implants on the contra-lateral side, where the implants were placed 4 mm apart creating a split mouth design too. The quantitative evaluation was performed comparatively on radiographs taken at t 0 (immediately after implantation) and at t 8 weeks (after termination). The samples were scanned by micro-computed tomography (µCT) to quantify the first bone to implant contact (fBIC) and bone volume/total volume (BV/TV). Mixed model regressions using the nonparametric Brunner-Langer method were used to determine the effect of inter-implant distance on the measured outcomes. RESULTS: The change in bone level was determined using radiography and its mean was 0.05 mm for an inter-implant distance of 3 and 0.00 mm for a 2 mm distance (P = 0.7268). The mean of this outcome was 0.18 mm for the 3 mm and for 4 mm inter-implant distance (P = 0.9500). Micro-computed tomography showed that the fBIC was always located above the reference, 0.27 and 0.20 mm for the comparison of 2-3 mm (P = 0.4622) and 0.49 and 0.34 mm for the inter-implant distance of 3 and 4 mm (P = 0.1699). BV/TV inside the defined parallelepipedic masks reached 82.38% for the 2 mm inter-implant distance and 85.00% for 3 mm, P = 0.8432. For the comparison of the 3-4 mm inter-implant distance, the means were 84.69% and 84.38%, respectively, P = 0.8401. Non-inferiority tests for the smaller inter-implant distances for both comparisons showed similar differences and similar tolerance ranges. CONCLUSION: The effect of a smaller interproximal distances between implants on bone level, fBIC and BV/TV assessed by two convergent investigation methods, radiology and µCT, was similar to that of larger distances. Implants can potentially be placed 2 mm apart instead of 3 mm and 3 mm apart instead of 4 mm when platform switching is utilized. Further research with a conventional platform is warranted.

Effect of interimplant distance (2 and 3 mm) on the height of interimplant bone crest: a histomorphometric evaluation.

BACKGROUND: Implants restored according to a platform-switching concept (implant abutment interface with a reduced diameter relative to the implant platform diameter) present less crestal bone loss than implants restored with a standard protocol. When implants are placed adjacent to one another, this bone loss may combine through overlapping, thereby causing loss of the interproximal height of bone and papilla. The present study compares the effects of two interimplant distances (2 and 3 mm) on bone maintenance when bone-level implants with platform-switching are used. METHODS: This study evaluates marginal bone level preservation and soft tissue quality around a bone-level implant after 2 months of healing in minipig mandibles. The primary objective is to evaluate histologically and histomorphometrically the affect that an implant design with a horizontally displaced implant-abutment junction has on the height of the crest of bone, between adjacent implants separated by two different distances. RESULTS: Results show that the interproximal bone loss measured from the edge of the implant platform to the bone crest was not different for interimplant distances of 2 or 3 mm. The horizontal position of the bone relative to the microgap on platform level (horizontal component of crestal bone loss) was 0.31 ± 0.3 mm for the 2-mm interimplant distance and 0.57 ± 0.51 mm above the platform 8 weeks after implantation for the 3-mm interimplant distance. CONCLUSIONS: This study shows that interimplant bone levels can be maintained at similar levels for 2- and 3-mm distances. The horizontally displaced implant-abutment junction provided for a more coronal position of the first point of bone-implant contact. The study reveals a smaller horizontal component at the crest of bone than has been reported for non-horizontally displaced implant-abutment junctions.