Abstract
Objectives: To investigate the effects of a coffee beverage and two whitening systems on the surface roughness and gloss of glazed Lithium Disilicate Glass-Ceramics (LDGC) for computer-aided design/computer-aided manufacturing (CAD/CAM) systems. Methods: Sixty-eight LDGC disks (12 x 10 x 2 mm) were prepared from blocks of CAD/CAM systems (IPS e.max CAD ceramic). Baseline measurements for surface roughness (Ra) and gloss (GU) were taken using a 3-D optical profilometer and a glossmeter, respectively; then specimens were randomized into four groups (n = 17). All specimens were immersed in a coffee solution (24 h x 12 days) then subjected to two whitening systems. G1-negative control (kept moist x 7 days); G2-positive control (brushed with distilled water, 200 g/load, 2 min twice daily x 7 days); G3-whitening toothpaste (Colgate optic white; relative dentin abrasivity (RDA) = 100, 200 g/load, 2 min twice daily x 7 days); and G4-simulated at-home bleaching protocol (Opalescence,15% carbamide peroxide (CP), 6 h/day x 7 days). The study outcomes were measured at baseline and after the treatments. Data were analyzed using paired T-test and one-way ANOVA (alpha = 0.05). Results: The mean surface roughness significantly increased (p <= 0.002) for all groups after the designated treatment protocols. Among groups, the mean surface roughness of G2 and G3 were significantly higher (p <= 0.001) (Ra: 0.51 and 0.57 mu m, respectively) compared to the control group (Ra: 0.23 mu m), and were not significantly different from G4 (Ra: 0.46 mu m). Surface gloss decreased with no significant change within or among groups after treatment. Conclusion: All glazed LDGC had a significant increase in surface roughness after being subjected to simulated 1 year of coffee drinking and whitening systems (15% CP and whitening toothpaste), and the greatest change was associated with brushing (simulating 8 months). However, coffee beverages and whitening systems had no significant effect on the surface gloss.