Effect of Thermocycling on Color, Surface Characteristics, Compressive Fracture, and Fracture Modes of Prosthetic CAD/CAM Ceramics After Smokeless Tobacco Immersion.

BACKGROUND The study aimed to assess effect of smokeless tobacco (ST) immersion with thermocycling (TC) on color of Vita Classical shade-guide, surface roughness (Ra) and roughness depth (Rz), and compressive fracture force (CFF) of hybrid polymer-infiltrated-feldspathic ceramic (Vita Enamic), leucite-Feldspathic glass (Vitablocs® Mark II), and zirconia-reinforced lithium silicate (Vita Suprinity) CAD/CAM prosthetic ceramic materials. MATERIAL AND METHODS A 48 samples were milled from Vita Enamic, Vita mark II, and Vita Suprinity. VitaPan shade-guide, Ra, and Rz were registered before ST immersion. Then, the same parameters were recorded again after 15 days of ST staining with and without TC. CFFs and fracture modes of samples after 3 months of aging were documented. RESULTS A slight change was observed in VitaPan shade-guide. Ra and Rz of Vita Suprinity (VS) recorded the highest values among ceramic groups at 3 time intervals. Increases in Ra and Rz were observed after immersion and staining with TC. ANOVA and Bonferroni post hoc tests were used. Significant differences among and between groups were noticed only before immersion in ST and TC, with P value ³0.00. The highest mean value and SD of CFFs (MPa and Newton) were recorded in Vita Suprinity, followed by Vita Enamic (VE) and Vita mark II (VMII). Reparable fracture was higher in VMII and VS. CONCLUSIONS ST staining and TC caused color changes in VitaPan shade-guide and increases in Ra and Rz of tested materials, with highest and lowest values recorded in VS and VE. CFFs were marginally equal to clinically accepted values for VS and equal or slightly higher than the half values for VE and VMII groups.