Clinical and Retrospective Evaluation of 4.1- or 4.3-mm-Diameter Implants Placed Immediately in the Molar Region: A Preliminary Study

PurposeThe purpose of this study was to evaluate the clinical and radiographic performance of 4.1- or 4.3-mm-diameter implants placed immediately in the molar region.Materials and MethodsTwenty-nine patients (14 men and 15 women, aged 21-71 years) received 38 implants that were placed immediately in the molar region. Of the implants, 19 (50%) were placed in the maxilla and 19 (50%) in the mandible. Thirty-eight prostheses (19 single restoration and 19 partial fixed prostheses) were fabricated. The diameter of the implant type was 4.1 mm (15 implants, 39%) or 4.3 mm (23 implants, 61%). Clinical and radiographic assessments of implants, prostheses, and peri-implant tissues were performed at 1 month, 3 months, and 6 months and then every 6 months after definitive restoration.ResultsKaplan-Meier survival estimates showed a 97.4% probability of implant survival to 36 months. The mean time of implant follow-up was 36 months, with a maximum of 75 months and minimum of 4 months. Cement dissolution occurred in 1 partial fixed prosthesis. Screw loosening occurred in 2 single-crown restorations in 1 patient. No abutment, screw, or implant fixture fractures were observed during the follow-up periods. The mean cervical bone loss of 38 implants measured 0.31 ± 0.06 mm mesially and 0.31 ± 0.07 mm distally 1 year after implant installation. There were no significant differences in implant survival and cervical bone loss based on anatomic location, gender, and prosthesis type.ConclusionsThis study describes successful outcomes after the use of 4.1- or 4.3-mm-diameter implants placed immediately in the molar region. Further comprehensive maintenance practices and follow-up schedules are required.