Immediate function with fixed implant-supported maxillary dentures: A 12-month pilot study

Statement of problem. Immediate occlusal loading of dental implants in the edentulous mandible has proven to be an effective, reliable, and predictable procedure. There is little long-term data available on similar treatments in the edentulous maxilla. Purpose. The purpose of this study was to evaluate the 12-month implant survival after immediate loading of 4 to 6 implants with fixed screw-retained prostheses in edentulous maxillae. Material and methods. Twenty-one patients, edentulous or with remaining teeth to be extracted in the maxilla, received 4 to 6 implants (n = 111). The patients were restored with screw-retained fixed provisional prostheses supported by palladium-alloy frameworks within 24 hours after surgery. Insertion torques for implants were at least 40 Ncm. Implants, grouped as tapered or cylindrical screws, were placed in healed bone or extraction sockets. Implants were also classified as either vertical or off-angle. Definitive prostheses were placed after a mean healing time of 18 weeks. Radiographic examinations were made at the time of placement of provisional prostheses and 12 months later. Between-groups bone resorption was compared using 2-way ANOVA (alpha = .05). Results. The mean follow-up time for all of the patients was 20 months (range, 13 to 28 months). The cumulative implant survival rate at the 12-month follow-up visits (after surgery) was 92.8%; the prostheses survival rate was 100%. No significant differences were found between the survival of tapered or cylindrical screw-type implants placed in postextraction sockets versus those in healed edentulous sites or between vertical and off-angle placed implants. Eight implants failed during the first 3 months, 5 of which were the most distal implants. The mean reduction in marginal bone height over the 12-month observation period was 0.84 mm (CI 95%; 0.68-0.99 mm). Conclusions. In this study with 12-month follow-up, 4 to 6 implants were sufficient to successfully support fixed implant screw-retained prostheses in the edentulous maxillae of 21 patients.