Document Type

Article

Publication Date

2023

Abstract

Objective: To evaluate the influence of restoration material type (CAD/CAM lithium disilicate blocks and reinforced composite blocks) and restoration design on fracture resistance of molars with MOD cavities. Methods and Materials: A total of 54 sound human molars were divided into 2 groups (n=9) according to: 1) material type: lithium disilicate CAD/CAM blocks and reinforced composite CAD/CAM blocks; 2) restoration design: overlay with intra-coronal extension or without intra-coronal extension. Additional 18 samples were assigned to positive control group (sound molars, n=9) and negative control group (unrestored MOD cavities, n=9). Standardized MOD cavities were prepared with occlusal width 3 mm, cavity depth 4 mm and cavity walls with occlusal divergence of 8-10 degrees. Gingival steps were prepared proximally with depth and width of 2 mm. Occlusal reduction was 2 mm for functional cusps and 1.5 mm for non-functional cusps. Occlusal margins A were prepared in concave chamfer finish line. Cavities receiving overlays without intra-coronal extension were filled with nanohybrid resin composite core. Restorations were manufactured using CEREC. All specimens were subjected to thermocycling (5000 cycles). Fracture resistance test was done using universal testing machine. The load to fracture was recorded in Newton. Data were statistically analyzed by ANOVA and Student-t test. Results: Study variables and their interactions showed no significant effect on fracture resistance. There was no significant difference in maximum load mean values between all study groups. Conclusion: CAD/CAM fabricated overlays (either lithium disilicate or composite) can restore fracture resistance of human molar teeth with MOD cavities. CAD CAM composite blocks are considered as promising materials and an alternative to lithium disilicate CAD CAM blocks in restoring MOD cavities with or without intra-coronal extension design.

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