Microleakage along the implant–abutment interface: a systematic review and meta-analysis of in vitro studies

Purpose This systematic review aimed to evaluate the incidence of microleakage events (IME) and to identify the potential factors influencing the sealing ability of the implant–abutment interface (IAI) under in vitro investigation. Material and methods An electronic search of MEDLINE (PubMed), EMBASE, and Web of Science databases, combined with a manual literature search was conducted up to September 2022. In vitro studies that reported the degree of microleakage at IAI under dynamic loading conditions were included. A meta-analysis was performed to calculate the mean values of the incidence of microleakage events. Subgroup analysis and meta-regression were conducted to further investigate the effect of different variables. Results 675 studies were identified following the search process and 17 in vitro studies were selected according to the eligibility criteria. The weighted mean incidence of microleakage events was 47% (95% confidence interval: [0.33, 0.60]), indicating that contamination was observed in nearly half of the samples. Concerning possible factors that may influence microleakage (e.g., loading condition, assessment method, implant–abutment connection design, types of abutment material, the use of sealing agents), loading condition ( p = 0.016) was the only variable that significantly influenced IME in the meta-regression analysis. Conclusions The results demonstrated that dynamic loading significantly increases the potential of bacterial penetration at the implant–abutment junction. The results should be interpreted carefully due to the data heterogeneity and further well-conducted in vitro studies with homogeneous samples are needed to standardize the methodologies. Graphical Abstract