Impact of Thermocycling on the Fracture Strength and Failure Type of Different CAD/CAM Ceramics after Saudi Coffee Staining.

AIM: This study aimed to evaluate the effect of thermocycling and Saudi coffee staining on the fracture forces and failure types of four computer-aided design and manufacturing (CAD/CAM) ceramic materials.

MATERIALS AND

METHODS

Ninety-six specimens were prepared from four CAD/CAM ceramics (n = 24 specimens per material): Vitablocs Mark II (feldspathic), Ceramill Zolid PS (zirconia), Vita Suprinity (zirconia-reinforced lithium silicate), and IPS e.max CAD (lithium disilicate). For each material, specimens were allocated equally into two subgroups (n = 12) according to thermocycling exposure: with thermocycling (n = 12) and without thermocycling (n = 12). All specimens underwent 2-month Saudi coffee immersion; thermocycled subgroups were subsequently subjected to 15,000 cycles between 5°C and 55°C. Fracture strength (N) was measured using a universal testing machine, and failure types were classified under a stereomicroscope. Statistical analysis used Shapiro-Wilk, Mann-Whitney, Kruskal-Wallis, and Fisher's exact tests (p < 0.05).

RESULTS

Zirconia exhibited the highest fracture forces in both conditions (768.06 N with thermocycling; 766.53 N without thermocycling), whereas Vitablocs Mark II showed the lowest (331.69 N with thermocycling; 341.28 N without). No significant differences between both conditions were observed for any ceramic type (all p > 0.05). For failure types, significant differences were detected among ceramic types in both conditions (p < 0.001). Reparable failure (type I) dominated in zirconia (66.7-75.0%) and IPS e.max CAD (50.0%), and nonreparable failure (type III) was prevalent in Vita Suprinity (33.3%-41.7%) and Vitablocs Mark II (41.7%-50.0%). No thermocycling-related differences in failure type were found (p > 0.05).

CONCLUSION

Thermocycling had no significant effect on fracture forces or failure types for any of the ceramic types, suggesting that thermal aging does not substantially alter their mechanical performance.

CLINICAL SIGNIFICANCE: Clinicians should consider patients' coffee consumption habits when selecting ceramic materials for dental restorations. Given the daily fluctuations in oral temperature, CAD/CAM materials must possess high fracture strength to ensure their resistance to forces encountered during daily oral functions, contributing to the long-term clinical success of dental prostheses. How to cite this article: ALhendi KD, Impact of Thermocycling on the Fracture Strength and Failure Type of Different CAD/CAM Ceramics after Saudi Coffee Staining. J Contemp Dent Pract 2025;26(8):752-758.