Effects of metformin on the bioactivity and osseointegration of dental implants: A systematic review

Dental implants are prosthetic devices that are surgically placed in direct contact with the jawbone to support intra-oral functions and esthetics. Diabetes mellitus may contribute to peri-implant bone loss. During the last few years, there have been attempts to reduce this bone loss and improve the survival rate of implants. Metformin, an anti-diabetic drug known for its osteogenic properties, is thought to prevent peri-implant bone loss in diabetic patients. Although several studies have been conducted to study metformin's effect on diabetic and non-diabetic study models, no systematic review has analyzed and summarized these studies critically. Therefore, the objectives of this systematic review were to summarize the outcomes of these studies and critically appraise them. Seven studies were included in this systematic review. Four studies used only animal models, two used both animal and cell culture models, and one used only cell culture studies. The general characteristics and outcomes of the included studies were summarized, and Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines were used to assess the quality of the animal studies. In vitro studies indicate that metformin may induce stem cells to undergo osteoblastic differentiation to produce a higher amount of bone and may also improve osseointegration. Nevertheless, several studies had potential sources of bias. Therefore, it is recommended that emphasis be placed on increasing the quality of future animal studies and human trials to determine the effects of metformin on the osseointegration of dental implants. Future studies are needed with adequate follow-up to evaluate the efficacy of metformin in improving the osseointegration of dental implants.