Effect of bar designs on peri implant tissues health: a systematic review

Different characteristics of bars (cross-sectional shape, diameter, distal extension etc) lead to different biomechanical behavior (retention and stress) with implants and peri-implant tissues. Aim: To evaluate the impact of bar designs in fully edentulous arch (in the maxilla and/or mandibula), with 4 implants or more, on the peri-implant soft and hard tissues. Two reviewers searched for observational studies, RCT and in vitro studies, published on five main databases and three from the grey literature, without restrictions on February 2022. Of the 2784 selected articles, 6 met the inclusion criteria. Three RCT evaluated peri-implant health tissues in full edentulous arches with 4 or 6 implants rehabilitated with implant bar overdentures. One prospective study with 5 years follow-up evaluated the success/survival rate of implants and implant bar overdentures. Overall, 231 subjects were enrolled in our systematic review with 936 implants. Overdentures’ survival rate was 100%. There was a trend that plaque indices and gingival indices were low in all of the studies, however no statistical analysis was done due to the lack of information. There is data suggesting that distal extension, diameter of the bar, bar material, and cross-sectional shape do have an impact on the peri-implant bone stress. However, due to the lack of information in the included studies, we cannot confirm if bar characteristics affect the peri-implant tissues health.