# Wear resistance and surface roughness assessment of CAD/CAM graphene-reinforced PMMA versus conventional PMMA crowns

## TL;DR

This study compares the wear resistance and surface roughness of graphene-reinforced PMMA and conventional PMMA crowns after simulated aging.

## Contribution

The study introduces a direct comparison of graphene-reinforced PMMA and conventional PMMA under artificial aging conditions.

## Key findings

- Graphene-reinforced PMMA and conventional PMMA showed no significant difference in surface wear resistance.
- Surface roughness did not differ significantly between the two materials before or after thermocycling.
- Thermocycling significantly reduced surface roughness in both materials.

## Abstract

To evaluate the graphene-reinforced PMMA wear resistance and surface roughness compared to PMMA after accelerated artificial aging.

Twenty molar-shaped crowns were fabricated (n = 10): graphene-reinforced PMMA (G) and PMMA (P), and an intraoral scanner digitized them. After thermomechanical aging, equivalent to 6 months of clinical service, the same scanner rescanned each crown. 3D analysis software calculated the wear loss volume of tested crowns. Twenty virtual discs were designed and milled from the two tested materials (n = 10). The discs were subjected to thermocycling, equivalent to 6 months of clinical service. Before and after thermocycling, a non-contact optical profilometer quantified the surface topography of all discs for assessment of surface roughness (Ra). Data were analyzed using ANOVA, Student’s t, and Bonferroni’s post-hoc tests (P ≤ 0.05).

Both 2D and 3D analysis approaches showed no statistically significant difference in surface wear between the P and G groups (P-value = 0.053, Effect size = 1.268; P-value = 0.649, Effect size = 0.271), respectively. Surface roughness did not differ statistically between the two materials independent of thermocycling (P-value = 0.172, Effect size = 0.150). Mean Ra decreased significantly after thermocycling in both groups regardless of material type (P-value = 0.035, Effect size = 0.320). For PMMA, the mean Ra did not change significantly after thermocycling. While mean Ra decreased significantly following the thermocycling of graphene-reinforced PMMA.

Both conventional PMMA and graphene-reinforced PMMA exhibited comparable performance in terms of surface wear resistance and surface roughness, regardless of artificial aging.