Aim: (PRIMARY) Assess the changes in bone level (6 and 12 months after implant placement) between the test (definitive abutment (DEF)) and control (healing abutment (HEA)) groups. (SECONDARY) Assess the changes in bone level (6 and 12 months after implant placement) between the 1 mm high abutment group and 2 mm abutment group. Evaluate changes in implant stability recorded with analysis of the resonance frequency (RFA) Osstell system, at 6 and 12 months after implant placement, between the control group (HEA) and test (DEF). For the DEF group, the abutment was placed at the time of the surgery and was never removed. For the HEA group, the abutment was removed three times during the manufacture of the crowns. The abutments used were 1 mm high (Subgroup A) and 2 mm high (Subgroup B). Materials and methods: A total of 147 patients were selected between 54.82 ± 11.92 years old. After implant placement, patients were randomly distributed in the DEF and HEA group. After the implant placement, a periapical radiograph was taken to assess the peri-implant bone level; the same procedure was carried out 6 and 12 months post-placement. To compare the qualitative variables between the groups (HEA/DEF), the Chi-square test was used; for quantitative (MANOVA). Results: After a year, the accumulated bone loss was 0.48 ± 0.71 mm for the HEA group and 0.36 ± 0.79 mm for the DEF group, without statistical significance. Differences were only found due to timing (time) between 0 and 6 months (=0.001) and 0 and 12 months (0.001), with no differences attributable to the study groups (DEF and HEA). The accumulated bone loss (1 year) was 0.45 ± 0.78 mm for the 1 mm abutment group and 0.41 ± 0.70 mm for the 2 mm abutment group (p = 0.02). No differences were observed in implant stability between groups. Conclusions: The "One Abutment-One Time" concept does not reduce peri-implant bone loss compared to the connection-disconnection technique. The height of the abutment does influence bone loss: the higher the abutment, the lower the bone loss.
Keywords: connection and disconnection abutment; dental implants; implant bone loss; implant collar; implant neck; implant-abutment connections; marginal bone level.