Effects of toothbrushing with conventional and whitening dentifrices and thermocycling on optical and surface properties of stained and glazed CAD/CAM ceramics

Abstract

The aim of this study is to evaluate the influence of toothbrushing with conventional and whitening dentifrices, followed by thermocycling, on optical and surface properties of stained and glazed CAD/CAM feldspar porcelain (VITABLOCS Mark II), zirconia-reinforced lithium silicate (VITA Suprinity) and partially-stabilized zirconia (IPS e.max ZirCAD). Bar-shaped specimens (n=20; 12 x 10 x 1.5 mm) will be obtained, crystallized, polished, and receive staining and glazing procedures. Then, they will be randomly divided into two groups: CV (n=10; conventional dentifrice; Colgate Total 12 Clean Mint) and CL (n=10; whitening dentifrice, Colgate Total 12 Professional Whitening) to be submitted to thermomechanical aging by 100,000 cycles of toothbrushing, followed by 12,000 cycles of thermocycling, simulating 10 years of clinical function. The L*, a*, and b* color coordinate data will be obtained before and after the aging period with a spectrophotometer (VITA Easyshade V) to calculate differences in color (Delta E00) and opalescence (OP). Digital images will be obtained under UV light with a DSLR camera for fluorescence analysis at the different periods, initial, 10-years. It will also be performed surface roughness analysis (Sa) in 3D laser confocal microscopy and chemical and elemental characterization in energy-dispersive X-ray spectroscopy (EDX). Data will be subjected to normality and homoscedasticity tests to select the statistical method to analyze the results with a 95% significance level.