Effect of surface treatment protocols and thermocycling on the optical, surface, and mechanical properties of additively manufactured resin materials.

OBJECTIVES

This study evaluated the effects of surface treatment protocols and thermocycling on the optical, surface, and mechanical properties of additively manufactured resins.

MATERIALS AND

METHODS

Five materials (saremco print CROWNTEC, VarseoSmile Crownplus, VarseoSmile TriniQ, VarseoSmile TriniQ for Formlabs, and Ceramic Crown) were assigned to six groups: control, silane, sandblasting (SB), SB+silane, hydrofluoric acid (HFA), and HFA+silane. After surface treatments and 5,000 thermocycles, color change (ΔE₀₀), translucency (ΔTP₀₀), gloss, surface roughness (Ra), and microhardness (VHN) were measured. Data were analyzed using robust ANOVA and aligned rank transform (ART) mixed ANOVA with Holm-adjusted multiple comparisons (α = 0.05).

RESULTS

Material type, surface treatment, and aging significantly affected all evaluated parameters (p < 0.001). Following surface treatment (T1), SB and SB + S groups exhibited significantly higher surface roughness and microhardness compared with control, silane, HFA, and HFA + S groups (p < 0.001). In terms of ΔE₀₀, SB and SB + S groups exceeded the clinical acceptability threshold (ΔE₀₀ > 1.8), whereas C, S, HFA, and HFA + S groups remained below the perceptibility threshold at T1. After thermocycling (T2), clinically unacceptable color changes were observed in most treatment groups, gloss values decreased significantly, and microhardness increased (p < 0.001). ΔTP₀₀ values were significantly influenced by material type (p < 0.001) but not consistently by surface treatment. Gloss values decreased significantly over time (p < 0.001), with the lowest values observed at T2. Among the materials, Ceramic Crown showed significantly higher microhardness and lower color change compared with the others (p < 0.05).

CONCLUSIONS

Surface treatments and thermocycling significantly affect additively manufactured resins; mechanical pretreatments improve hardness but may compromise optical properties.

CLINICAL RELEVANCE: Careful selection of surface treatment protocols is required to achieve a balance between mechanical performance and esthetic outcomes in additively manufactured restorations.