IADR Abstract Archives
Effect of Endocrown Restoration with CAD/CAM Ceramic on the Mechanical Behavior of Endodontically Treated Teeth
Objectives: The mechanical behavior of endocrowns in the presence of zirconia are unknown. This in vitro study evaluated the mechanical behavior of endodontically treated teeth restored with endocrowns obtained by different CAD/CAM ceramic systems.
Methods: 60 human lower molars endodontically treated were prepared for endocrown beig that the occlusal box with approximately 5 mm in depth, 4 mm in the buccal-lingual direction, and 6 mm in the mesiodistal direction. The teeth were randomly distributed into 4 groups (n = 15), according to the different ceramics systems used: LC–leucite-based glass ceramics; LD–lithium disilicate-based glass ceramic; LSZ–glass ceramic based on zirconium-reinforced lithium silicate; ZR–monolithic zirconia. After the adhesive bonding, the samples were submitted to the accelerated thermomechanical aging initially with a 80 N load, followed by 120, 160, 200, 240, 280 and 320N stages with a maximum of 20,000 cycles each, until 140,000 cycles. After that, the samples were submitted to a static test of fracture resistance in a universal test machine. The failure mode of the samples was evaluated qualitatively through a stereomicroscope and an electronic scanning microscopy.
Results: Statistically significant difference among the groups was observed (p < 0.05). LC, LD and LSZ were similar to each other (1178 N, 1935 N, and 1859 N, respectively) and different from ZR (6333 N), which presented the highest fracture resistance. LC and LD groups showed a higher ratio of reparable failures, while LSZ and ZR, irreparable. The fractographic analysis indicated regular failure pattern to ZR and irregular failure pattern to the other ceramics studied.
Conclusions: The mechanical performance of monolithic zirconia was better than that of the other ceramic endocrowns considered in this research; however, monolithic zirconia presented a higher rate of tooth structure catastrophic failure.
Methods: 60 human lower molars endodontically treated were prepared for endocrown beig that the occlusal box with approximately 5 mm in depth, 4 mm in the buccal-lingual direction, and 6 mm in the mesiodistal direction. The teeth were randomly distributed into 4 groups (n = 15), according to the different ceramics systems used: LC–leucite-based glass ceramics; LD–lithium disilicate-based glass ceramic; LSZ–glass ceramic based on zirconium-reinforced lithium silicate; ZR–monolithic zirconia. After the adhesive bonding, the samples were submitted to the accelerated thermomechanical aging initially with a 80 N load, followed by 120, 160, 200, 240, 280 and 320N stages with a maximum of 20,000 cycles each, until 140,000 cycles. After that, the samples were submitted to a static test of fracture resistance in a universal test machine. The failure mode of the samples was evaluated qualitatively through a stereomicroscope and an electronic scanning microscopy.
Results: Statistically significant difference among the groups was observed (p < 0.05). LC, LD and LSZ were similar to each other (1178 N, 1935 N, and 1859 N, respectively) and different from ZR (6333 N), which presented the highest fracture resistance. LC and LD groups showed a higher ratio of reparable failures, while LSZ and ZR, irreparable. The fractographic analysis indicated regular failure pattern to ZR and irregular failure pattern to the other ceramics studied.
Conclusions: The mechanical performance of monolithic zirconia was better than that of the other ceramic endocrowns considered in this research; however, monolithic zirconia presented a higher rate of tooth structure catastrophic failure.