Mechanical Properties of CAD/CAM Feldspathic Ceramics: Literature Review of IN VITRO Studies

Introduction: Contemporary ceramic materials allow a biomimetic replacement of dental tissues. On account of the existence of several commercial feldspathic ceramics together with a study priority focused on adhesion and aesthetics a necessity arises in complementing these studies with information regarding mechanical properties. Objectives: To report in vitro studies which tested the flexural strength and fracture toughness of CAD/CAM feldspathic ceramics, identifying gaps in the scientific evidence. Methods: A systematic search was conducted in the PubMed/Medline and Scopus databases with the following search terms: "feldspathic ceramic/porcelain", "CAD-CAM", "fracture toughness", "flexural strength","three point bending", "four point bending", "strength". Studies which included CAD/CAM feldspathic ceramic in comparison with other CAD/CAM ceramics, published after 2010, were included. The retrieval and selection process followed PRISMA guidelines, and was conducted by two reviewers independently. Results: The search retrieved 118 articles. Of these, only 8 met the established inclusion criteria. The flexural strength and fracture toughness of feldspathic ceramics assessed in these studies were inferior compared to all the CAD/CAM alternatives. The same brand of ceramic material was consistently reported throughout the existing stuides. Conclusion: CAD/CAM feldspathic ceramics are outperformed by the rest of the CAD/CAM ceramics in terms of mechanical properties. Only one study assessing different brands of CAD/CAM feldspathic ceramic was found. This illustrates the urgent need for further research. Clinical implications: Insight towards the mechanical properties of contemporary CAD/CAM ceramics will serve as a guide for evidence based clinicians, increasing the restoration's longevity. Keywords: Feldspathic ceramic, CAD/CAM, flexural strength, fracture toughness, strength