Biomechanical, esthetic, and hygienic considerations of materials for overdenture bars: A systematic review

Purpose

The bar-clip retention system is the most retentive; however, the best material choice is questionable. So, this review aimed to answer “How does the material used for overdenture bars influence the results?”.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were followed, and the protocol was registered in the Open Science Framework. A personalized search strategy was applied in four databases and grey literature. The selection process was carried out in two stages independently by two reviewers according to the eligibility criteria, in vitro or in vivo experimental articles that evaluated the influence of bar material on the results. The risk of bias was analyzed using a checklist of important parameters.

Results

Three hundred and sixty-one articles were found, and after the removal of duplicates, 308 were evaluated, of which six met the eligibility criteria, and all had a low risk of bias. The qualitative analysis was subdivided into stress distribution, bar deformation, clip retention, esthetic, and hygiene.

Conclusion

1) PEEK and BioHPP when compared to metallic alloys, are promising materials for the bar because they have a lower modulus of elasticity, low affinity for bacterial adhesion, and greater esthetic; 2) Clinical studies with longer follow-up times are required to evaluate the biomechanical performance of zirconia bars (ZrO₂) because their stiffness and hardness can lead to increased stress concentration and replacement of the plastic clip, although they are associated with high esthetic and low affinity for bacterial adhesion.