In vitro comparison of surface roughness and gloss of prefabricated zirconia crowns before and after simulated brushing

Background: Prefabricated zirconia crowns (PZCs) are widely used in pediatric dentistry due to their superior esthetics and durability. However, limited information is available regarding their surface behavior after long-term brushing. This study aimed to evaluate and compare the surface roughness (Ra) and gloss values of three different PZC brands—NuSmile, ProfZr Crown, and Kids Crown—before and after brushing. Methods: Thirty PZCs (n = 10 per group) were embedded in transparent cold-cure acrylic blocks, with the labial surface oriented parallel to the ground to standardize positioning for the brushing procedure. Specimens were subjected to standardized brushing using an oscillating-rotating electric toothbrush and low-abrasive children’s toothpaste. Surface roughness was measured using a contact profilometer, and gloss was assessed with a glossmeter. Measurements were recorded before and after brushing. Intragroup and intergroup comparisons were performed using Wilcoxon, Kruskal-Wallis, and analysis of variance (ANOVA) tests depending on data distribution (α = 0.05). Results: Pre-brushing Ra values differed significantly between groups (p = 0.0012), with ProfZr showing the highest initial roughness. Post-brushing Ra values did not differ significantly (p = 0.668), but ∆Ra values were significantly higher in NuSmile and Kids Crown compared to ProfZr (p = 0.0017). A significant increase in Ra was observed after brushing in NuSmile (p = 0.002) and Kids Crown (p = 0.006), but not in ProfZr. Gloss values decreased in all groups, though not significantly (p = 0.108). Initial gloss values significantly differed between brands (p = 0.0096), with NuSmile exhibiting the lowest gloss. ∆Gloss values were not significantly different among groups (p = 0.565). Conclusions: Surface roughness and gloss of PZCs vary by brand and respond differently to brushing. While ProfZr maintained surface stability, NuSmile and Kids Crown showed increased roughness and gloss loss. Surface finishing may influence these outcomes and should be considered in crown selection.

Prefabricated zirconia crowns; Surface roughness; Gloss; Toothbrushing simulation

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