Purpose: Implant treatment using osseointegrated implants has been performed for more than 40 years, but limited knowledge is available on how treatment outcomes have changed over time. The aim of this study was to report and compare the prosthetic treatment outcomes from two patient cohorts provided with fixed implant prostheses in the edentulous maxilla between 1986 and 1987 (early) and 2001 to 2004 (late) at the same clinic. Materials and Methods: The two groups of patients comprised 76 and 109 edentulous patients consecutively provided with 450 and 670 Brånemark System implants and fixed screw-retained prostheses, respectively. Both groups were followed for 5 years with regard to prosthetic treatment, clinical maintenance, and complications. Results: Altogether, 37 patients (20%) were lost to follow-up during the 5 years, and more patients were noncompliant in the late group (P .05). Prosthetic treatment was performed using significantly less chair time in the late group (P .05), and 22 and 68 patients were followed for 5 years without any reported complications in the early and late groups, respectively (P .05). The 5-year prosthesis cumulative survival rate was 97.1% in the early group and 100.0% in the late group. Patients in the late group presented fewer problems with diction and veneer fractures, and fewer patients had their prostheses temporarily removed for adjustments (P .05). Conclusion: Prosthetic treatment and maintenance of implant-supported fixed prostheses improved significantly between the groups.