Surface degradation of glass ceramics after exposure to acidulated phosphate fluoride

ABSTRACT

OBJECTIVE: This study evaluated the surface degradation effect of acidulated phosphate fluoride (APF) gel exposure on the glassy matrix ceramics as a function of time. MATERIAL AND METHODS: Disc-shaped ceramic specimens (N = 120, 10/per ceramic material) were prepared in stainless steel molds (inner diameter 5 mm, height 2 mm) using 6 dental ceramics 3 indicated for ceramic-fused-to-metal (Vita Omega 900, Carmen and Vita Titankeramik), 2 for all-ceramic (Vitadur Alpha and Finesse® Low Fusing) and 1 for both types of restorations (IPS d.SIGN). The specimens were wet ground finished, ultrasonically cleaned and auto-glazed. All specimens were subjected to calculation of percentage of mass loss, surface roughness analysis and topographical description by scanning electron microscopy (SEM) before (0 min) and after exposure to 1.23 percent APF gel for 4 min and 60 min representing short- and long-term etching effect, respectively. The data were analyzed using two-way ANOVA with repeated measures and Tukey's test (a=0.05). RESULTS: Significant effect of the type of the ceramics (p=0.0000, p=0.0031) and exposure time (p=0.0000) was observed in both surface roughness and percentage of mass loss values, respectively. The interaction factor between both parameters was also significant for both parameters (p=0.0904, p=0.0258). Both 4 min (0.44±0.1 - 0.81±0.2 mm) and 60 min (0.66±0.1 - 1.04±0.3 mm) APF gel exposure created significantly more surface roughness for all groups when compared to the control groups (0.33±0.2 - 0.68±0.2 mm) (p<0.05). There were no significant differences in percentage of mass loss between the ceramics at 4 min (p>0.05) but at 60 min exposure, IPS d.SIGN showed the highest percentage of mass loss (0.1151±0.11). The mean surface roughness for Vita Titankeramik (0.84±0.2 mm) and Finesse® Low Fusing (0.74.±0.2 mm) was significantly higher than those of the other ...