Search

PURPOSE: The purpose of this study was to evaluate radiographic bone levels adjacent to implants placed in fresh extraction sockets (ESs) and immediately loaded with a fixed full-arch provisional restoration compared to bone levels adjacent to implants placed in native bone (NB) under the same restorative conditions. MATERIALS AND METHODS: Patients with a hopeless maxillary and/or mandibular dentition had their remaining teeth extracted and 6 to 8 implants placed and restored within 72 hours. Radiographs were obtained at time 0, 3 to 6 months, and annually for 5 years. The radiographs were digitized, and the bone level changes were measured using a computer-assisted method. RESULTS: A total of 139 implants, 42 ES and 97 NB, placed in 17 patients were evaluated. The overall results indicated that for all implants (ES + NB), 0.60+/-0.71 mm of bone was lost after 6 months; 1.17 +/-0.59 mm of bone was lost after 18 months; 0.87+/-0.76 mm bone was lost after 36 months; and 1.35 +/-0.42 mm of bone was lost after 60 months. When stratifying for NB versus ES implants, it was found that for NB implants, 0.75+/- 0.21 mm of bone was lost after 6 months; 1.31 +/- 0.91 mm of bone was lost after 12 months; 1.07+/-0.21 mm of bone was lost after 36 months; and 1.45 +/- 0.49 mm of bone was lost after 54 months. For ES implants, 0.14 +/-0.33 mm of bone was lost after 6 months; 1.02 +/-0.27 mm of bone was lost after 12 months; 0.86+/-0.42 mm of bone was lost after 36 months; and 1.30 +/-0.48 mm of bone was lost after 54 months. CONCLUSION: The combination of ES and NB implants can be immediately loaded with a fixed full-arch prosthesis and remain stable for greater than 5 years. The bone loss adjacent to these implants is similar to that seen surrounding those placed and restored using traditional protocols. [ABSTRACT FROM AUTHOR]

The primary objective of this proof-of-principle study was to evaluate the outcome of vertical ridge augmentation in a standardized dog model by combining purified recombinant platelet-derived growth factor (rhPDGF-BB) and a block of deproteinized cancellous bovine bone. The secondary objective was to determine the value of a resorbable barrier membrane to improve the efficacy of the procedure. Six adult foxhounds were committed to bilateral surgical extraction of all four mandibular premolars. A vertical alveolar ridge defect was created at the time of the extractions. Three months later, the artificially created defects were grafted: Group A used a deproteinized bovine bone block in combination with a collagen barrier membrane, group B used a deproteinized bovine bone block infused with rhPDGF-BB only, and group C included a deproteinized bovine bone block infused with rhPDGF-BB, plus a collagen resorbable barrier membrane. After 4 months, the animals were sacrificed. Histologic examination of group B revealed a large amount of newly formed bone, and a large amount of bone-to-implant contact was visible in the areas of bone regeneration extending over the top of the implant cover screw. The results of this preclinical canine study provide proof-of-principle that rhPDGF-BB, used in combination with a deproteinized bovine block without placement of a barrier membrane, has the potential to regenerate significant amounts of new bone in severe mandibular ridge defects. In addition, the results seem to point to the importance of the periosteum as a source of osteoprogenitor cells in growth factor-mediated regenerative procedures. [ABSTRACT FROM AUTHOR]