Which prosthetic treatment concepts present a reliable evidence-based option for the edentulous maxilla related to number and position of dental implants?

Purpose: The objective of this systematic review, serving as a basis for an expert consensus conference, was to answer the following questions: Which prosthetic treatment concept related to implant number and position presents a reliable evidence-based option for the edentulous maxilla? How many implants should be installed and what kind of implant prosthesis works most efficiently related to this number? Previously, these questions could not be answered adequately, although several meta-analyses considering the respective issues have been published. However, some reports included study designs with a low level of evidence (e.g. retrospective) and observation periods of less than 3 years. In this systematic review, stricter inclusion criteria were used in an attempt to reach a higher level of evidence. Materials and methods: An electronic MEDLINE (PubMed) search was conducted to identify all relevant studies concerning either fixed or removable implant prosthetics. The most important inclusion criteria were: the trial had to be an randomised controlled trial (RCT) or at least prospective (minimum observation period of 3 years); endosseous implants were examined; details on implant and/ or prosthesis survival were provided. Results: The search revealed 988 abstracts of possible relevance. Twenty-nine publications met the inclusion criteria. In total, 7028 implants and 1130 patients were observed. Because of the heterogeneity among the included studies, a statistical analysis of the extracted data was questionable. Conclusions: Owing to different study protocols (with different implant systems, loading protocols, surgical procedures, designs of supraconstructions, etc.), varying statistical methods, and often missing information of the included studies, highly reliable conclusions are hardly possible. Welldesigned RCTs are needed to provide scientifically validated prosthetic treatment protocols. Parole chiave: edentulous maxilla, fixed, implant, overdenture, prosthesis, systematic review