Periimplant bone changes in different abutment heights and insertion timing in posterior mandibular areas: Three-year results from a randomized prospective clinical trial.

AIM: To compare the influence of the abutment height and its insertion timing on the marginal bone change (MBC) variation of implants placed at posterior mandibular partial edentulous areas in a medium follow-up period. MATERIAL AND METHODS: This randomized clinical trial (RCT) comprised a sample of patients with posterior mandibular edentulous areas, treated with at least two implants and distributed into three groups: implants connected to a 2 mm height abutment during the surgical stage (Group A); implants connected to a 1 mm height abutment during the surgical stage (Group B); and implants connected to a 2 mm height abutment after 2 months (Group C). Clinical and radiographic measurements were performed during a 36-month period (T4). The MBC was set as the main variable in study. Statistical significance was set at 0.05. RESULTS: A total of 29 subjects and 59 implants were enrolled in this study. A mean MBC of 0.35 ± 0.46 mm, 0.60 ± 0.81 mm, and 0.71 ± 0.90 mm was computed for groups A, B and C, respectively, at T4. Significant differences were found between groups A and C in terms of MBC variation after 3 years of treatment (p = .048). Multiple linear regression analysis showed a significant influence of the first-year MBC and the abutment insertion timing has independent predictor variables for the MBC assessed at T4. CONCLUSION: The installation of 2-mm prosthetic abutments, at the time of implant placement, in areas with limited keratinized mucosa presents as a favorable treatment option in terms of periimplant marginal bone maintenance.

Influence of the abutment height and connection timing in early peri-implant marginal bone changes: A prospective randomized clinical trial.

AIM: The aim of this study was to compare the influence of the abutment height and insertion timing on early marginal bone loss (MBL) in posterior mandibular partial implant-supported restorations. MATERIAL AND METHODS: The study was planned as a prospective, randomized, controlled parallel group including subjects in need of at least two implants for the restoration of an edentulous posterior mandibular area. The patients were allocated into Groups A (implants immediately connected to 2-mm height abutments), B (immediately connected 1-mm height abutments), and C (2-mm abutments were inserted in a second-stage surgery). Each subject was placed in a 1-year follow-up program, including examination assessment of various soft tissue and bone-level parameters. RESULTS: A total of thirty-three patients, including sixty-eight implants, were enrolled in this study. One implant was lost on group C after the first month of healing. A mean MBL change of 0.719 ± 0.361, 0.651 ± 0.379, and 0.754 ± 0.672 mm was computed for groups A, B, and C, respectively, with no significant differences found. The early MBL at T1 was an independent predictor variable for the marginal bone alterations that were assessed at T3 (p < 0.001). CONCLUSION: The first-month MBL variation is a predictor factor of the bone alterations that might occur after 1 year of treatment. The early connection of final prosthetic abutments with distinct heights does not seem to reduce the 1-year MBL rate when compared with traditional treatment protocols.