Changes in color and brightness of stained and/or glazed CAD-CAM ceramics after thermocycling and toothbrushing with conventional and whitening dentifrices.

Author(s)

Bruno Arruda Mascaro

• Document type: Master's Dissertation
• Press: Araraquara. 2021-09-20.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2021-08-09
• Advisor: José Maurício dos Santos Nunes Reis

Abstract

This in vitro study aimed to evaluate the changes in color and brightness of extrinsically stained and/or glazed CAD/CAM ceramic materials from leucitereinforced glass ceramic ([EMP], IPS Empress® CAD), lithium disilicate ([EMAX], IPS e.max® CAD), high translucent fully-stabilized zirconia ([PAN], Prettau® 4 Anterior®), and a hybrid ceramic ([ENA], VITA Enamic®) after toothbrushing with conventional and whitening dentifrices, followed by thermocycling. Bar-shaped (n=40; 12 x 10 x 1.5 mm) specimens were obtained and divided into two groups according to the surface treatment: glazed only (n=20; GLAZE) or stained then glazed (n=20; STAIN/GLAZE). Each group were subdivided in two other groups to be subjected to accelerated thermomechanical aging by toothbrushing (50,000 cycles, 1.96 N, 1.0 Hz), varying the dentifrice type in conventional (n=10; Colgate Total 12 Clean Mint, RDA 70) or whitening (n=10; Colgate Total 12 Professional Whitening, RDA 96), and thermocycling (6,000 cycles, 5.0-55ºC, 30 s), simulating 5 years of clinical service. Initial and post-aging data were obtained with a spectrophotometer (VITA Easyshade® V) according to CIELAB (L*, a* and b*), and CIEDE2000 (L*, C* and H*) parameters to calculate changes in color (ΔEab and ΔE00), and brightness (ΔL). The data were analyzed for normality (Shapiro-Wilk; α=0.05), and homogeneity of variances (Levene; α=0.05). 2-way ANOVA followed by Welch’s method, and Games-Howell post-test (p<0.05) were performed. Regardless the dentifrice, ENA presented the highest ΔEab (p<0.01) and ΔE00 (p<0.01) values from GLAZE and STAIN/GLAZE groups. Compared to EMP and EMAX, PAN samples showed significant changes in ΔEab from the STAIN/GLAZE group and in ΔE00 from the GLAZE and STAIN/GLAZE groups, in relation to EMAX. Except for EMP, the other materials of the GLAZE group showed a decrease in brightness after conventional brushing. PAN and ENA from the GLAZE group showed reduced brightness after brushing with whitening dentifrice. ENA from the STAIN/GLAZE group presented the greatest reduction in brightness, regardless of the dentifrice. Only ENA showed ΔEab values above clinically perceptible treshold (ΔEab > 1.2). All groups presented clinically acceptable values for ΔEab (< 2.7), and ΔE00 (< 1.8). In fact, the color and brightness of the extrinsically stained and/or glazed CAD/CAM ceramics changed after thermomechanical aging by means of toothbrushing followed by thermocycling. Despite influencing the color and brightness of some materials, the different dentifrices were not a clinically significant variation factor in the optical properties evaluated for the extrinsically characterized monolithic ceramics. (AU)

• FAPESP's process: 18/24595-7 - Color change, roughness and surface topography of stained monolithic ceramics after thermocycling and toothbrushing with conventional and whitening dentifrices
• Grantee: Bruno Arruda Mascaro
• Support Opportunities: Scholarships in Brazil - Master