A randomized controlled clinical trial of edentulous patients treated with immediately loaded implant-supported mandibular fixed prostheses.

Purpose: A 1-year blinded two-arm parallel randomized controlled clinical trial was conducted to test the null hypothesis that immediate loading of four dental implants between the mental foramina with a fixed prosthesis has no benefits compared with the conventional loading technique in terms of implant success and clinical function.

Materials And Methods: Forty-five patients, completely edentulous in the mandibles seeking implant-supported prostheses at the Faculty of Dentistry, University of Toronto, were recruited. Four TiUnite dental implants (NobelBiocare®, Göteborg, Sweden) were placed following the one-stage surgical protocol. Immediately after surgery, the patients were randomly assigned to either study arms by a third independent party. In the experimental arm (EA), existing mandibular denture was converted into an interim implant-supported fixed bridge (ISFB) on the same day of surgery. In the control arm (CA), the mandibular denture was hollowed out and relined with a soft tissue reline. The implants were loaded with the permanent ISFB at least 3 months postsurgery. Patients were assessed by a calibrated independent investigator at 2, 6, and 12 months following completion of treatment.

Results: A total of one hundred sixty implants were placed. Due to anatomical limitations, one patient was excluded from the study. Four patients in the EA did not receive intervention as allocated and were transferred to the CA. Implant success rate was comparable between the two arms and exceeded 96%. Marginal bone loss was statistically significantly more in the immediate loading arm, -0.296 mm versus -0.037 mm (intention to treat: p = .002; per protocol: p = .021). The relatively early intervention and insertion of the final prosthesis in the immediate arm, when bone healing and remodeling process had not yet been completed, might explain the difference in the amount of bone loss.

Conclusion: Immediate loading of four dental implants with a fixed prosthesis in the edentulous mandible is a feasible treatment option and leads to a substantial improvement in perceived oral health status.