Abstract

Objective: The objective of this study was to evaluate the chromatic effect of two post-curing protocols, (1) manufacturer-recommended standard post-curing (SPC) and (2) standard post-curing plus an additional post-curing cycle (APC), on three types of 3D-printed resins for provisional crowns. Methods: Ninety provisional crowns were printed (n = 30 per resin type-Power Resins Temp, Freeprint Temp, and NextDent C&B) and divided into two groups: SPC (19 min at 30 °C, n = 15 per group) and APC (19 min + 19 min at 30 °C, n = 15 per group). Color coordinates (L*, a*, and b*) were recorded using a spectrophotometer before and after each post-curing protocol to calculate the total color difference (ΔE). Data were analyzed using paired t-test, Wilcoxon signed-rank test, and one-way ANOVA (α = 0.05). Results: After APC, statistically significant changes were observed in the b* coordinate, indicating a lower yellowing tendency for Freeprint Temp (p = 0.018) and NextDent C&B (p = 0.023). No significant changes were found in L* and a* coordinates. However, the total color difference (ΔE) remained below the clinical acceptability threshold (ΔE < 3.3) in all groups. Statistical analysis showed no significant differences in ΔE between the resin brands (p = 0.914). Conclusions: An additional post-curing protocol is a safe procedure from a chromatic standpoint, as it does not compromise the chromatic esthetic outcomes of 3D provisional resins. Clinical Significance: The additional post-curing protocol does not compromise the immediate aesthetic appearance of 3D-printed provisional resins, confirming its optical safety during laboratory processing. Nevertheless, validating its long-term mechanical stability and behavior under simulated oral conditions remains necessary prior to full clinical implementation.

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