Effect of Thermodynamic Aging on Colour Stability, Roughness and Flexural Strength of Two CAD/CAM Lithium Disilicate Glass Ceramics

Abstract

Objective: This study aimed to assess and compare the effect of thermodynamic aging on colour stability, roughness, and flexural strength of two CAD/CAM Li2Si2O5 ceramics. Materials and Methods: A total of 40 rectangular bar samples were fabricated representing two groups according to type of ceramic (20 samples each). Group I:IPS e.max CAD and Group II:Rosetta SM. Samples of each group were randomly distributed among two subgroups (10 samples each) according to testing procedure and thermodynamic aging condition: Subgroups IA and IIA (10 samples each) act as a control for flexural strength testing in non-aged condition. For Subgroups IB and IIB (10 samples each) both colour and surface roughness (Ra) were measured before thermodynamic aging. Then the samples were subjected again to colour, surface roughness and finally flexural strength (MPa) tests after thermodynamic aging. Data were statistically analyzed. Results: Neither colour nor flexural strength of the examined ceramic materials were significantly affected by thermodynamic aging. Regarding surface roughness, Rosetta SM was significantly affected by aging, while IPS e.max CAD did not. Conclusion: Concerning the measured parameters Rosetta SM is comparable to IPS e.max CAD being as clinically acceptable even after aging.