Influence of thermal aging on surface roughness of conventional and 3D-printed materials used in intraoral appliance manufacturing.

Abstract

Background: Intraoral appliances are widely used in dentistry. Their surface roughness may influence patient comfort, biofilm formation and durability.

Objectives: The aim of the study was to evaluate and compare the effect of thermocycling on the surface roughness (Ra) of different materials used for the fabrication of intraoral appliances.

Material and methods: Seventy-two standardized specimens (40 mm × 10 mm × 2 mm) were fabricated from 3 materials: a self-curing poly(methyl methacrylate) (PMMA) resin (PMMA group); a light-cured urethane dimethacrylate (UDMA)-based resin (UDMA group); and a stereolithography (SLA) 3D-printed resin (SLA group). Surface roughness was measured before and after thermocycling (5,000 and 10,000 cycles between 5°C and 55°C) using a contact profilometer. Values were reported as mean (M) ±standard deviation (SD). The data was analyzed using repeated-measures or ordinary one-way analysis of variance (ANOVA), followed by Bonferroni-corrected post hoc tests (α = 0.0167).

Results: The UDMA group exhibited the lowest mean initial Ra values (0.078 ±0.020 μm). Thermocycling induced changes in surface roughness. In the PMMA group, a significant increase in mean Ra was observed after 5,000 cycles (0.103 ±0.028 μm before vs. 0.167 ±0.059 μm after; p = 0.0001) and after 10,000 cycles (0.107 ±0.024 μm before vs. 0.205 ±0.060 μm after; p < 0.0001). The increase in mean Ra following thermocycling was significantly greater in the PMMA group compared to the other groups (mean ΔRa after 5,000 cycles: 0.064 ±0.035 μm; after 10,000 cycles: 0.098 ±0.046 μm; all p < 0.0001).

Conclusions: Materials used for the fabrication of intraoral appliances exhibit material-specific responses to thermal aging. The light-cured UDMA-based resin demonstrated superior surface integrity after aging, whereas conventional PMMA and the 3D-printed resin were more susceptible to surface alterations.