Long-term survival rates of implants supporting overdentures

The study aims were to evaluate survival rates of dental implants in patients wearing maxillary and mandibular overdentures in relation to age, sex, smoking, implant splinting or non-splinting, the maxilla rehabilitated, and number of implants per dental arch. This was a prospective study of patients who were completely edentulous in either mandible or maxilla or both, rehabilitated with implant-retained overdentures, with a follow-up of at least 3 years. 95 patients with 107 overdentures were supported by 360 implants were included in the study. Rehabilitations were monitored over an average of 95 ± 20.3 months (range 36-159). Implant survival in the maxilla was 91.9% and in the mandible 98.6%, representing a statistically significant difference (P < .05). Age, sex and implant splinting did not influence survival rates significantly. Smokers presented a lower survival rate. Implant numbers in the maxilla had a significant influence on survival, 100% for 6 but 85.7% for 4. Three mandibular implants achieved higher survival rates (100%) but with 2 (96.6%) or 4 (99%) survival was lower, although without significant difference. Long-term results suggest that 3-implant mandibular overdentures have an equivalent survival rate to 4-implant overdentures. In the maxilla, results showed that 6 implants may be the best treatment strategy. For smokers with fewer implants retaining the overdentures, there were higher numbers of implant failures.