Retentive Value and Cyclic Fatigue Resistance of Polyetheretherketone Clasps as an Alternative to Cobalt-Chrome Clasps for Removable Partial Dentures: A Systematic Review

The aim of the review was to evaluate polyetheretherketone (PEEK) clasps used for removable partial dentures (RPDs) as alternatives to conventional cobalt-chrome (CoCr) clasps and assess their retentive potential and behavior in terms of resistance to cyclic fatigue for long-term use. This review was performed according to the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) criteria and was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023459699). An electronic search was performed independently by two examiners in PubMed/MEDLINE and ScienceDirect databases for articles published in English between 2017 and 2023. Risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal tool. Initially, 92 articles were identified and subjected to screening. Among these, six articles met the eligibility criteria for further analysis. The inter-rater agreement for article selection was high (91.67% agreement, Cohen's kappa coefficient = 0.83), with no exclusions based on risk of bias assessment. PEEK clasps, though generally exhibiting lower retention compared to CoCr, still met clinical standards. Factors affecting their performance included manufacturing, dimensions, and aging. While PEEK offers advantages in stress distribution and enamel wear reduction, concerns persist about its mechanical properties compared to CoCr, necessitating careful design considerations. Within the limitations of our systematic review, PEEK clasps may be a promising alternative to CoCr clasps in RPDs, potentially offering aesthetic benefits and reduced stress on abutment teeth. A global approach that analyzes both in vitro and in vivo studies is recommended to fully assess their performance.