Influence of dental implant/mini-implant design on stress distribution in overdentures: a systematic review.

PURPOSE: Critically evaluate the existing literature and answer the question, "Does the dental implant/mini-implant design influence the stress distribution in prosthetic overdentures according to finite element analysis?". METHODS: This systematic review was registered in the Open Science Framework (osf.io/2bquj) and followed the PRISMA protocols. The custom search strategy was applied to 4 databases. In vitro experimental studies that evaluated the influence of dental implant/mini-implant design on stress distribution in overdentures by FEM, without time and language restrictions, were included. The selection process was carried out in two stages by two reviewers independently. Risk of bias analysis was performed by a checklist of important parameters. RESULTS: Sixty articles were evaluated by their title and abstract, four were selected for full reading, three were relevant, and nine were included by additional search. The 12 studies have a low risk of bias. The meta-analysis could not be performed due to the heterogeneity of the data (implant type, design variation, load intensity, and direction). CONCLUSION: It can be inferred from the evaluated literature that design modifications influence the stress distribution, but as the FEM presents limitations inherent to the in vitro study, clinical trials are necessary to infer the effectiveness of the modifications. It should be noted that there is no consensus on which is the best thread design and that implants with a very narrow diameter are subject to the highest stress concentration.