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Influence of substrate, simulated gastric juice, dentifrice, and illuminant on optical properties and surface analysis of CAD/CAM materials


The aim is to evaluate the effects of gastric juice and dentifrices on optical and surface properties of CAD/CAM materials bonded on two substrates and analyzed under different illuminants. Disks (7.5 x 1.0 mm; N=150/material) from Lava Ultimate (3M ESPE), Grandio Blocs (VOCO), VITA Enamic (VITA Zahnfabrik), and VITABLOCS Mark II (VITA Zahnfabrik); and of dentin (N=300) and composite resin (N=300) will be obtained. Specimens will be prepared with disks of each material being bonded to disks of dentin or composite resin with dual resin cement. In study 1, disks will be allocated into 4 groups (n=15), according to substrate and exposure: (1) dentin/artificial saliva; (2) dentin/gastric juice; (3) composite resin/artificial saliva; or (4) composite resin/gastric juice. Exposure to simulated gastric juice or artificial saliva, followed by toothbrushing, will be simulated for 5 years of clinical function. In subproject 2, disks of material will receive staining and glazing procedures and, then, will be divided into 6 groups (n=15), according to substrate and dentifrice: (1) dentin/conventional; (2) dentin/whitening; (3) dentin/charcoal activated; (4) composite resin/conventional; (5) composite resin/whitening; (6) composite resin/charcoal activated. The toothbrushing will be performed for a 5-year clinical simulation. In both subprojects, data will be obtained with a spectrophotometer under illuminants D65, A or F2 for analysis of lightness, color coordinates, color change, and coefficients of light reflection, transmission, absorption, and dispersion, applying the Kubelka-Munk theory. The surface roughness and topography will be evaluated by confocal microscopy and scanning electron microscopy, respectively. Energy-dispersive X-ray spectroscopy (EDX) will be performed for chemical characterization and elemental analysis. Data will be submitted to statistical analysis with a significance level of 95%. (AU)

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