Fracture Resistance and Failure Mode Analysis of Biomimetic Overlays Constructed from Different Machinable Blocks and Subjected to Thermo-Dynamic Aging. An In Vitro Study

Purpose: To evaluate the fracture resistance and failure modes of biomimetic adhesive overlays constructed from two different types of machinable blocks after thermodynamic aging. Materials and methods: Twenty-two sound maxillary premolars were prepared for adhesive overlays and randomly allocated into two groups (n=11) according to the material used for overlay construction: Group CT: advanced lithium disilicate with virgilite (CEREC Tessera), and Group BC: ceramic reinforced composite (Brilliant Crios) materials. Thermodynamic aging was done to all bonded samples followed by fracture resistance test. Modes of failure were evaluated with digital microscope at 10X magnification. Results: Group CT recorded higher fracture mean values (1065.4 ±79.3) than group BC mean values (930.4 ±41.2). Failure mode distribution scores between the two material groups were statistically non-significant. Conclusions: CEREC Tessera showed better fracture resistance than Brilliant Crios. Both materials showed similar percentages of catastrophic failure. The majority of samples in both groups exhibited repairable fractures.