Influence of aging and manufacturing techniques on the physical and mechanical stability of occlusal device materials: A systematic review

STATEMENT OF PROBLEM: Computer-aided design and computer-aided manufacturing (CAD-CAM) has introduced alternatives to the conventional fabrication of occlusal devices, though data on their physical, mechanical, and long-term durability remain limited. PURPOSE: The purpose of this systematic review was to assess the stability of the physical and mechanical properties of occlusal device materials subjected to degradation. MATERIAL AND METHODS: This review was registered in the open science framework (OSF) (osf.io/rjgs6) and involved 8 databases and nonpeer-reviewed sources, supplemented by manual screening. Independent study selection followed predefined criteria, and the risk of bias was assessed with the RoBDEMAT tool. RESULTS: Across 21 studies, milled composite resins outperformed 3-dimensionally (3D) printed and heat-polymerized or autopolymerized polymethyl methacrylate (PMMA) under artificial degradation, with printing and postpolymerization parameters influencing the physicomechanical stability of 3D printed composite resins. CONCLUSIONS: Milled materials exhibited the greatest stability, heat-polymerized PMMA demonstrated intermediate performance, and autopolymerized resins performed the worst. Despite greater degradation susceptibility, advances in formulation and postprocessing suggest promising potential for 3D printed resins.