Prosthetic Outcome in Edentulous Maxillae related to Implant Number

Objectives: The purpose of this systematic review was to find out, which prosthetic treatment concept related to implant number and position presents a reliable option for the edentulous maxilla. In this context, some meta-analyses have been published, recently. However, these reports did not only include prospective (some of them only short-term) but also retrospective studies, and did not differentiate between machined or rough-surfaced implants. To reach a higher level of evidence, in this systematic review stricter inclusion criteria were used. Methods: An electronic MEDLINE (PubMed) literature search was conducted to identify all relevant studies concerning implant prosthetics in the edentulous maxilla, either fixed or removable. Different keywords were used for 6 different searching paths. The most important inclusion criteria were: the trial had to be a RCT or at least prospective (minimum observation period 3 years), the implants examined were rough-surfaced, details on implant and/or prosthesis survival were provided. Results: The search revealed 1186 abstracts of possible relevance. 102 full-text articles were finally selected. Only 6 (1 for removable and 5 for fixed prostheses) studies met the inclusion criteria. Due to the inclusion criterion “rough-surfaced implants”, 16 other clinical studies had to be excluded. In total 1431 implants were observed, the implant number varied from 4 to 10 implants. Because of the heterogeneity and the low number of the included studies, a statistical analysis of the extracted data was questionable. The survival rates for removable prostheses after 0-10 years ranged from 88% (Dolder bar) to 95% (milled bar). For fixed prostheses a survival rate of 100% after 3 years as well as cumulative survival rates of 100% after 10 years were reported. Conclusions: Due to the very low number of included studies highly reliable conclusions are not possible. Well-designed RCTs are urgently needed to provide scientifically validated prosthetic treatment protocols.