Effects of Toothbrushing and Thermocycling on Color, Opalescence, Fluorescence, and Surface Analyses of Stained CAD-CAM Glass-ceramics and Zirconia.

Abstract

Purpose: To assess the impact of toothbrushing and thermocycling on color, opalescence, fluorescence, and surface of extrinsically stained CAD-CAM ceramics.

Materials and methods: Specimens (n=20) of VITA Mark II (VBII), VITA Suprinity (SUP), and IPS e.max ZirCAD (ZIR) were stained and glazed, then divided into two groups based on dentifrice (n=10; conventional or whitening). Aging was simulated via 100,000 toothbrushing cycles followed by 12.000 cycles of thermocycling. Color differences (ΔE00) and opalescence were calculated. Images under ultraviolet lamp were obtained for fluorescence analysis. Surface roughness was analyzed using 3D laser confocal microscopy, and chemical elemental characterization was determined using energy-dispersive X-ray spectroscopy (XEDS). Statistical analyses (α=0.05) included 2-way ANOVA and Tukey HSD tests for ΔE00, and 3way ANOVAs with Sidak post hoc test for opalescence, fluorescence, and surface roughness. ΔE00 values were compared to perceptibility and acceptability thresholds.

Results: Higher ΔE00 were observed for VBII in the whitening group and SUP in the conventional group. All ΔE00 values remained below perceptibility. ZIR exhibited the lowest opalescence and fluorescence before and after aging. SUP and ZIR showed a significant reduction but continued to exhibit fluorescence after aging. VBII whitening and SUP conventional exhibited increased roughness. XEDS indicated that extrinsic characterization persisted on the surface with subtle changes in elemental composition after aging.

Conclusions: The findings suggest that toothbrushing with different dentifrices and thermocycling can impact the aesthetic outcome and surface of stained CAD-CAM ceramics. Despite these, the materials evaluated maintained color stability and resisted the proposed aging.