Rehabilitation of edentulous mandibles by means of turned Branemark System® implants after one-stage surgery:: A 1-year retrospective study of 152 patients

Background: Rehabilitation of the edentulous mandible with oral implants is today predominantly executed with one-stage surgery and early or immediate loading. It is generally claimed that the outcome is similar to that of the classic two-stage technique. Purpose: The aim of the present investigation was to retrospectively evaluate the 1-year results of one-stage surgery and early loading performed in edentulous mandibles in a large group of patients. The outcome was compared with that of a study, from the same clinic (control), that used the two-stage surgical technique in edentulous mandibles and whose data were well controlled. Materials and Methods: The study included 152 individuals with 750 turned Branemark System(R) implants of various designs placed in edentulous mandibles by means of one-stage surgery. The prosthetic procedure was commenced at a mean of 13 days after the surgical intervention. Intraoral apical radiography was performed at the time of prosthesis placement and at the I-year annual checkup. Comparison of failure rates between the test and the control groups was made by means of the chi-square test. Results: A total of 18 implants in 12 patients in the study group were found to be mobile up to and including the first annual checkup, equivalent to a 1-year implant cumulative survival rate (CSR) of 97.5%. The corresponding CSR for the control group was 99.7%. Differences between the two groups in regard to implant survival reached significant levels when analyzed with the chi-square test (p <.05). No Such significant difference was seen on the patient level (p >.05). Because of implant failures one prosthesis in the study group was remade. The mean marginal bone resorption during the first year of function was 0.4 mm in both groups. Conclusions: The present investigation showed a high but (compared with the classic two-stage technique) somewhat lower CSR after 1 year for the one-stage technique. More prosthetic adjustments due to implant failures were observed in the study group, and the results emphasize the need for large study samples in order to statistically verify small differences between various treatment techniques.