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Abstract
Objectives: The purpose of this study was to evaluate the fracture resistance of two CAD/CAM endocrown materials using two bonding protocol; self-etch and total etch. Materials and methods: 32 endodontically treated teeth were prepared divided into two main groups; group 1: Ceramill endocrowns (n=16) and group 2: Cerasmart endocrowns (n=16) and subgrouped (n=8) according to the bonding protocol into total etch and self-etch and bonded using RelyX Ultimate. All samples were subjected thermomechanical aging using chewing simulator to resemble 1 year of intraoral function, then fracture resistance was tested using instron testing machine. Results: Were analyzed using two-way ANOVA for comparing material group type and cementation approach effect on different variable studied. Chi square test was performed between fracture patterns. The ceramill comp endocrowns recorded higher mean fracture resistance (2420.178±553.3 N) than the cerasmart endocrowns; However, the difference was insignificant(p{u2265}0.5). The total etch bonding protocol recorded higher mean fracture resistance in ceramill comp (2532.282±605.26 N), while self-etch bonding protocol recorded a significantly higher mean fracture resistance in the cerasmart (2402.276±645.26). The failure mode of the two materials showed high prevalence of catastrophic fracture. Total etch showed higher repairable fracture pattern prevalence in both materials. Conclusions: Both cerasmart and ceramill comp are promising materials to be used for endocrowns in terms of the fracture resistance in the posterior lower region. Both self-etch and total-etch bonding protocols can be used successfully when bonding hybrid ceramic endocrowns with adhesive resin cement