Implant Treatment with Fixed Prostheses in the Edentulous Maxilla. Part 1: Implants and Biologic Response in Two Patient Cohorts Restored Between 1986 and 1987 and 15 Years Later

Purpose: Implant treatment has been performed for more than 45 years, but there is still limited knowledge on how treatment outcomes are changing over time. The aim of this study was to report and compare the treatment outcomes of two patient cohorts from the same clinic, rehabilitated with fixed implant prostheses in the edentulous maxilla between 1986 and 1987 (early) and 2001 to 2004 (late). Materials and Methods: The early group included 76 edentulous patients who were consecutively provided with 450 turned Brånemark System implants; the late group included 109 edentulous patients provided with 360 turned and 310 TiUnite Brånemark System implants. Both groups were followed and evaluated clinically and radiographically for 5 years according to similar protocols. Results: Altogether, 37 patients (20%) were lost to follow-up over 5 years; more patients were noncompliant in the late group (P .05). The 5-year overall implant cumulative survival rates were 93.4% and 97.3% for the early and late groups, respectively. In the early group, significantly more turned implants failed before prosthesis insertion compared to the outcome of TiUnite implants in the late group (P .05). Mean bone loss was comparable for the early and late groups during the 5 years of follow-up (0.5 ± 0.46 and 0.7 ± 0.76 mm, respectively), but more patients presented at least 1 implant with more than 2 mm of bone loss during the follow-up period in the late group (P .05). Mucosal hyperplasia and inflammation showed a trend of higher frequency at implants in the early group of patients (P > .05). Conclusion: Implant treatment was more predictable before loading in the late group of patients, related to the change in the implant surface (P .05). On the other hand, it was observed that the prevalence of patients with more bone loss at at least 1 implant (> 2 mm) was higher in the late group (P .05). This could possibly be attributed to a more bioactive implant surface and shorter healing period before implant surgery in the late group.