Accurate analysis of titanium and PolyEtherEtherKetone materials as an alternative to cobalt-chrome framework in removable partial denture: A systematic review

New materials have emerged in the dental field to replace the cobalt-chrome (CoCr) alloy used for the metal frameworks in removable partial denture (RPD) such as Titanium (Ti) and PolyEtherEtherKetone (PEEK). However, few studies have demonstrated their mechanical and biological performance. The purpose of this systematic review was to compare the performance of Ti and PEEK in RPD using CoCr metal framework as a reference. This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three data bases were analyzed, including PubMed/MEDLINE, Embase and Web of Science before March 2024. Only studies assessing the mechanical and/or biological properties of RPD in Ti, PEEK and CoCr were included. The quality of the studies was assessed by using the software Rayyan. The risks of bias were assessed with the methodological index for nonrandomized studies (MINORS). The mechanical (retention force, fatigue life, deformation strength, machinability, rigidity, porosity and surface roughness) and biological (plaque indices, ion release and biocompatibility) aspects were assessed. Among 138 articles identified, only 18 studies were included in this review. Majority had a low to moderate risk of bias. Retention forces and fatigue were significantly lower for Ti and PEEK than for CoCr, and the same was true for Ti rigidity. PEEK showed less deformation. Both materials were suitable for machining. In terms of biological properties, both materials showed adequate biocompatibility for clinical use. Ti and PEEK seems to be promising as alternative materials to CoCr frameworks for RPD, in terms of both their mechanical and biological performance. However, additional studies are needed to better understand their clinical and long-term limitations to enable the best-informed clinical choice for the patients and the professionals.