A retrospective clinical study of edentulous patients rehabilitated according to the 'all on four' or the 'all on six' immediate function concept.

PURPOSE: To present clinical results of an implant placement protocol using 4 or 6 implants supporting immediately loaded fixed prostheses. MATERIALS AND METHODS: This retrospective clinical study included 20 patients (restoring 19 maxillae and 9 mandibles) with 127 loaded implants that supported immediately fixed complete-arch acrylic prostheses followed for at least 2 years. Outcome measures were failures of the prosthesis and of the implants, an approximate radiographic evaluation, and any complication. RESULTS: A total of 116 implants were immediately loaded. Eleven implants were not immediately loaded because they did not reach the planned insertion torque. These implants were loaded after the osseointegration period when the final prostheses were delivered. Four implants failed during the osseointegration period and all of them were successfully replaced. The survival rate was 96.9% (96.7% in the maxilla and 97.2% in the mandible). No prosthesis was lost. Eight patients experienced fractures of their provisional prosthesis that were repaired in the clinic. Seven implants out of 127 experienced marginal bone loss up to the first and the second thread. CONCLUSIONS: The results indicate that the 'all on four' and 'all on six' immediate-function concept postextraction could be a viable and predictable treatment.