# Effects of Thermal Aging on Optical, Surface, Mechanical, and Biological Properties of CAD/CAM Polymer-Based Dental Materials

## TL;DR

This study examines how thermal aging affects the optical, surface, mechanical, and biological properties of polymer-based dental materials used in prosthetic restorations.

## Contribution

The study provides new insights into how thermal aging impacts the performance of PEEK, FRC, and G-CAM dental materials.

## Key findings

- Material-dependent differences in color stability, surface roughness, and microhardness were observed after thermal aging.
- Microhardness decreased in fiber-reinforced and graphene-reinforced materials but remained stable in PEEK.
- Chemical stability and cytocompatibility were preserved across all tested materials after thermal aging.

## Abstract

CAD/CAM polymer-based dental materials are increasingly used as metal-free alternatives for fixed and implant-supported restorations. High-performance polymers such as polyetheretherketone (PEEK), fiber-reinforced composites, and graphene-reinforced polymers have been introduced to improve material stability; however, evidence regarding the effects of thermal aging on their physicochemical and biological properties remains limited. In this study, PEEK, a fiber-reinforced composite (FRC), and a graphene-reinforced PMMA-based polymer (G-CAM) were evaluated. Twenty-seven disc-shaped specimens (10 × 2 mm; n = 9 per material) were fabricated and subjected to 10,000 thermal cycles between 5 and 55 °C. Color change (ΔE00), surface roughness (Ra), and Vickers microhardness (VHN) were measured before and after aging. Chemical stability was assessed using FTIR and Raman spectroscopy, surface morphology by SEM analysis, and biological safety by cytotoxicity testing. Material-dependent differences were observed in color stability, surface roughness, and microhardness after thermal aging (p < 0.05). Microhardness decreased in the fiber-reinforced and graphene-reinforced materials, whereas PEEK showed no significant change. Spectroscopic analyses indicated preserved chemical structure, and all materials demonstrated acceptable cytocompatibility. Thermal aging influenced material behavior while chemical stability and biological safety were maintained, highlighting the importance of considering aging behavior during material selection for prosthetic restorations.