Four-Millimeter Implants Supporting Fixed Partial Dental Prostheses in the Severely Resorbed Posterior Mandible: Two-Year Results

Abstract

Background: Reduced alveolar bone volume complicates implant dentistry. Purpose: In this prospective multicenter study, a new, 4-mm long Straumann SLActive implant (Ø 4.1mm) supporting a fixed dental prosthesis (FDP) in the severely resorbed posterior mandible was evaluated for two years. Material and Methods: Thirty-two patients (11 men, 21 women; mean age 64.1 years) participated. Ten to 12 weeks after single-stage surgery, a screw-retained FDP was attached to three or four 4-mm implants. Results and Discussion: One hundred implants were inserted. Three failed at surgery and four were lost before loading. Twenty-eight patients received FDPs (93 implants). Two patients were discontinued because of secondary exclusion criteria; therefore, 26 patients were followed up from baseline (BL). After 1 year, one patient insisted on removal of all implants and one patient died because of nonstudy-related complications. Twenty-four patients (87 implants) were eligible for examination 2 years post-loading. All implants were found to be stable [survival rate 95.7% (confidence interval, CI 88.8-98.3) after 1 year and 92.3% (CI 84.5-96.2) after 2 years]. The mean change from BL to 12 months was - 0.43mm (CI 0.31-0.59; p