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

PURPOSE: The 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 METHODS: Twenty-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.

RESULTS: Kaplan-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.

CONCLUSIONS: This 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.