Impact of Implant Length on Survival of Rough-Surface Implants in Nonaugmented Posterior Areas: A Systematic Review and Meta-Regression Analysis

Purpose: Short implants have been considered as an alternative to regular implants even where native bone is potentially adequate. Hence, the aim of this study was to evaluate the impact of implant length on its survival. Materials and Methods: A systematic literature search of randomized controlled trials and prospective studies was performed using the PubMed (MEDLINE), EMBASE, and Cochrane databases. Metaregression analysis determined the effect of the length on the implant survival rate. Results: Sixty-six studies comprising 4,525 implants were included in the meta-regression analysis. Overall, for each additional 1 mm of length, the survival rate was increased by 0.42 percentage points (P = .056). In the maxilla, an additional 1 mm in length implied 0.68 percentage points more in the rate (P .001), while in the mandible, statistical significance was not reached. Eventually, the implant survival rate in the 3- to 5-year period was strongly affected by the length of the implants in the maxilla, since it increased by 2% for each additional 1 mm of length. Conclusion: In the presence of adequate native bone, placement of longer/regular-sized implants should be chosen over placement of short implants in the maxilla. However, in a posterior mandible, short implants offer a judicious alternative. Keywords: dental implants, implant survival, review, short implants, systematic