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Abstract
This study was conducted to evaluate the fracture resistance of cerasmartcrownsusingtotal etch adhesive cement system (Rely X Ultimate) and self adhesive resin cement (Rely X Unicem). According to sample size calculation, a total of 24 Cerasmart crowns were constructed. The samples were divided into two equal groups (n=12) according to the type of resin cement used. group A: 12 samples (n=12) cemented withRelyX Ultimate (total etch) Universal Resin Cement. group B: 12 samples (n=12) cemented with RelyXUnicem (Self-Adhesive) Universal Resin Cement. 24 Freshly extracted , caries free human maxillary canines were prepared and mounted in epoxy resin blocks with 1 mm shoulder finish line , 1 mm axial reduction , 1.5 mm incisal reduction ,1 mm lingual clearance , angle of convergence 10 degrees and occlusogingival height of 5 mm. 24 Cerasmart crowns were fabricated and milled by Cerec MCXL with the aid of Cerec AC software (CerecOmnicam) (Cerec premium 4.4) with 1 mm cervical and middle thickness and 1.5 mm incisal thickness. The restorations were surface treated according to the manufacturer’s instructions, and cemented on their counter prepared canines using self adhesive resin cement for one group and total etch adhesive resin cement for the other group . After 24 hours of storage in distilled water and cyclic loading , the fracture resistance of the restorations was measured using universal testing machine (instron) with a load of 5 KN and cross-head speed of 1mm/min. The results showed that the group cemented with Total etchresin cement recorded higher fracture resistance mean value (553.68±94.71 N) than the group cemented with Self-adhesiveresin cement (341.07±58.16 N). The difference between both groups was statistically significant as indicated by t-test (t = 4.18, p value = .0004 < 0.05)