Simplified methods of implant treatment in the edentulous lower jaw. A controlled prospective study. Part I: one-stage versus two-stage surgery.

Abstract

The original protocol for Brånemark System implants in the mandible was a two-stage procedure with 3 months healing time. With five or six implants and a cast framework of gold, the treatment is rather expensive, and simplified methods would be desirable. The goal of this controlled serial study was to investigate the outcome of a simplified procedure with one-stage surgery, four Brånemark implants, shortened healing time, and a new titanium-acrylic fixed full prosthesis. Eighty-two patients were treated in three different groups at two specialist centers. All patients were provided with four implants, loaded with a Procera All-in-One bridge (Nobel Biocare, Gothenburg, Sweden) after 12 weeks. In group A (n = 30), one-stage surgery was combined with two-piece implants. In group B (n = 30), the control group, two-stage surgery and two-piece implants were used. In group C (n = 22), one-stage surgery was combined with one-piece implants. Marginal bone level was rated from radiographs at implant insertion, at baseline, and after 1 year. The survival rate after 1 year for group A was 93.3%; group B, 97.5%; and group C, 93.2%. The differences were not statistically significant. Between fixture insertion and baseline, the average bone loss for group A was 1.2 mm; group B, 1.3 mm; and group C, 1.3 mm. No complications in the form of bridge loosening or acrylic fractures were recorded during the first year. The survival rates and the marginal bone changes did not differ significantly between the one-stage groups and the control group. The survival rate and the marginal bone changes were similar for one-piece and two-piece implants. Four implants were sufficient to support full fixed prostheses in the mandibles. The Procera All-in-One bridges proved to be of high quality, and no complications were experienced. key words: endosseous implants, nonsubmerged implants, one-piece implants, prospective clinical study, submerged implants