What is the optimal number of implants for fixed reconstructions: a systematic review

Abstract

Objectives: To assess the 5-year and 10-year survival and complication rates of implant-supported fixed reconstructions in partially and totally edentulous patients with regard to the optimal number and distribution of dental implants.

Material and methods: This review was designed as a systematic review of the literature. A search strategy was developed and executed using an electronic and selective hand search for English-language articles in Dental Journals limited to human clinical trials. Search terms were grouped into categories for "problem" - "intervention" - "outcome". For articles retrieved by this search, abstracts were screened by two reviewers based on the inclusion criteria. Selected articles were then obtained in full texts. Finally, the selection based on inclusion/exclusion criteria was repeated for the full-text articles.

Results: Of the 210 titles retrieved by the search, 51 were selected for full-text review based on the information given in the abstract. From the full-text articles, a total of nine studies were included for this systematic review. In meta-analysis, prosthetic survival rates over 5 and 10 years for partial Fixed Dental Prostheses (FDPs) on two to four implants were estimated as 98.9% (95% CI: 98.5-99.2%) and as 97.8% (95% CI: 96.9-98.4%) respectively. A survival rate for maxillary Full-Arch Fixed Dental Prostheses (FAFDPs) on four to six implants after 5 years was assessed as 97.5% (95% CI: 94.1-98.9%) and a survival rate after 10 years as 95.0% (95% CI: 88.5-97.9%). The result for the survival rates in case of mandibular FAFDPs on four to six implants after 5 years was 97.9% (95% CI: 96.3-98.8%) and after 10 years 95.9% (95% CI: 92.8-97.7%). Specific implant-to-replaced-unit-ratios were not available in any of the studies.

Conclusion: For implant-supported FAFDPs, using 4-6 implants is a well-documented treatment option with high estimated 5-year survival of the construction. It is unclear whether three implants for supporting a FAFDP will achieve similar survival rates. The RCTs needed that report implant-to-replaced-units-ratios for partial FDPs and include 3 vs. 4-6 implants for supporting a FAFDP in the mandible.