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Purpose: This study sought to define the tissue responses at different implant-abutment interfaces by studying bone and peri-implant mucosal changes using a 5-year prospective randomized clinical trial design study. The conus interface was compared with the flat-to-flat interface and platform-switched implant-abutment systems. Materials and Methods: One hundred forty-one subjects were recruited and randomized to the three treatment groups according to defined inclusion and exclusion criteria. Following implant placement and immediate provisionalization in healed alveolar ridges, clinical, photographic, and radiographic parameters were measured at 6 months and annually for 5 years. The calculated changes in marginal bone levels, peri-implant mucosal zenith location, papillae lengths, and peri-implant Plaque Index and bleeding on probing were statistically compared. Results: Forty-eight conus interface implants, 49 flat-to-flat interface implants, and 44 platform-switched implants were placed in 141 subjects. Six platform-switched interface and eight flatto- flat interface implants failed, most of them within 3 months. After 5 years, 33 conical interface, 28 flat-to-flat interface, and 27 platform-switched interface implants remained for evaluation. Calculation of marginal bone level change showed a mean marginal bone loss of –0.16 ± 0.45 (–1.55 to 0.65), –0.92 ± 0.70 (–2.90 to 0.20), and –0.81 ± 1.06 (–3.35 to 1.35) mm for conical interface, flat-to-flat interface, and platform-switched interface implants, respectively (P < .0005). The peri-implant mucosal zenith changes were minimal for all three interface designs (0.10 mm and +0.08 mm, P > .60). Only 16% to 19% of the surfaces had presence of bleeding on probing, with no significant differences (P > .81) between groups. Interproximal tissue changes were positive and similar among the implant interface designs. Conclusion: Over 5 years, the immediate provisionalization protocol resulted in stable peri-implant mucosal responses for all three interfaces. Compared with the flat-to-flat and platform-switched interfaces, the conical interface implants demonstrated significantly less early marginal bone loss. The relationship of marginal bone responses and mucosal responses requires further experimental consideration. Keywords: esthetics, immediate loading, marginal bone levels, peri-implant mucosa, randomized controlled clinical trial

Purpose: The autogenous bone block graft is regarded as the gold standard material due to reported osteoconductive, osteoinductive, and osteogenic properties. Various intraoral donor sites for autogenous block grafts are presented in the literature. The aim of this study was to radiographically evaluate the maximum dimensions, volume, and bone quality values of these sites. Materials and Methods: According to the inclusion criteria, 50 cone beam computed tomography (CBCT) images from 50 subjects were evaluated. The maximum length, width, height, and volume of autogenous regions where block grafts could be harvested were measured. Radiographic bone quality was calculated by using Hounsfield units derived from CBCT (CBCT-HU). Results: The mean age of 50 subjects (19 men and 31 women) was 55.84 ± 15.9 years. In this study, the symphysis was the largest potential donor site (3.14 ± 1.05 cm3), while maxillary tuberosity was the smallest (0.53 ± 0.34 cm3). These results correlated with bone density values, where the symphysis retained the highest values (937.31 ± 160.59 CBCT-HU) and the maxillary tuberosity had the lowest values (360.87 ± 141.48 CBCT-HU). Conclusion: Intraoral bone blocks have restrictions due to surrounding vital anatomical structures. The surgeons should consider these vital structures using accurate CBCT evaluation. The volume and density of the maximal bone harvest from the symphysis was statistically higher in comparison with ramus, palatal, and maxillary tuberosity bone blocks. Keywords: augmentation, density, dental implant, imaging, tomography, volume