Method: The material for this retrospective analysis was selected from a prospective clinical study. Seventy-three RDPs supported by 234 Straumann implants and 107 abutment teeth were placed in 61 patients with a mean age of 65.4 years. Forty-five RDPs were located in the maxilla and 28 in the mandible, when 34 were solely implant-supported and 39 combined tooth-implant-supported. Kaplan–Meier analysis was performed to estimate survival without severe implant or abutment tooth related complications. The Cox regression model was used to isolate risk factors for the prognosis of abutment teeth and implants.
Result: Within a mean observation period of 3.24 years (maximum: 8.3ys) 6 implants failed and 11 implants were diagnosed with peri-implantitis. Four abutment teeth were extracted and 3 abutment teeth showed severe complications requiring extended interventions. After 5 years, Kaplan-Meier analyses revealed a probability of survival without severe complication for both abutment teeth and implants of 85% under solely implant-supported RDPs and 92% under combined tooth-implant-retained RDPs. Implant success under combined tooth-implant-supported RDPs (98%) was significantly higher (p<0.018) compared to 85% for exclusively implant-supported RDPs. Multivariate analysis revealed location as significant (p=0.029) risk factor for the incidence of severe implant related complications with a hazard rate of 4 for implants placed in the maxilla. Males (p=0.054) and implants under solely implant supported RDPs (p=0.053) showed a tendency to higher complication rates, whereas the number of abutments per RDP had no effect.
Conclusion: Teeth and implants can be combined to support double crown-retained RDPs without negative effect on implant prognosis.