Aim of the study: The aim of this study was to evaluate the changes in surface roughness and micro-hardness of four CAD/CAM materials after thermo-mechanical aging.
Materials and methods: Four commercially available CAD/CAM materials were investigated in this study; two ceramic materials; CEREC Blocs, Celtra Duo, and two hybrid ceramics; CERASMART and VITA ENAMIC. The materials' blocks were cut into 5 disks each and were subjected to thermo-mechanical aging through 250,000 thermocycles in a mechanical chewing simulator. Surface roughness and micro-hardness were evaluated for each material pre and post thermo-mechanical aging using digital image processing technology and Vickers hardness testing machine, respectively. Results were statistically analyzed using one way analysis of variance (ANOVA), Bonferroni Post Hoc test and paired t test (P≤0.05).
Results: Regarding surface roughness; there was no significant difference between all investigated materials before thermo-mechanical aging. After aging, all materials showed insignificant difference between them and insignificant change between pre and post aging with exception of CERASMART that showed significant increase in surface roughness. Regarding surface micro-hardness, the tested materials showed significant difference pre aging in the ascending order of Cerasmart < Enamic < Cerec Blocks < Celtra Duo. But after aging, all materials showed insignificant difference in surface micro-hardness between them and insignificant change between before and after the test.
Conclusions: Within the limitations of the current study, it can be concluded that although within the clinical acceptable range, the surface roughness of Cerasmart was significantly affected by the thermo-mechanical aging. The composition is still the most important parameter affecting the surface roughness and micro-hardness of CAD/CAM ceramic and hybrid ceramic materials