الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 116 |  |  |
| | | from | 116 | | |
Abstract
Purpose: The purpose of this in vitro study was to evaluate fracture resistance of ultrathin occlusal veneer fabricated by different CAD/CAM materials. Methods: The occlusal surface of 40 extracted lower premolars were prepared in the enamel layer and restored with occlusal veneers with fissures / cusp thickness of 0.5 /1ml made from two different dental CAD/CAM materials Groups of the study ,group I: lithium disilicate glass ceramic n=20 : was further divided into 2 subgroups according to thickness for each of them .subgroup A: (n=10) 0.5mm subgroup B: (n=10) 1mm ,group II: Cerasmart n=20 : is further divided in to 2 subgroups according to thickness for each of them .subgroup A: (n=10) 0.5mmsubgroup B: (n=10) 1mm. The occlusal veneers were etched with ceramic etch (Ips ceramic etching gel /ATZGELIVOCLAR AG) then bonded using an adhesive luting system (G-MULTI PRIMER and G-CEMTM Veneer) light cure adhesive resin cement (G-CEHTM veneer) The prepared teeth were etched phosphoric gel and bonded using Bisco All bond universal ®. All of specimens were subjected to load till fracture, these loads were recorded and statically analysed by using one way ANOVA. The mode of failure of specimen was classified , the correlation between fracture strength and mode of failure was analyses. Results: In this study The fracture strengths (Mean ± standard deviation ) of cerasmart 0.5mm (887.71±284.79N), 1mm (953.73±214.06N),and for lithium disilicate 0.5 mm (455.16±134.96N),1mm(768.59±154.08N). Cerasmart had significantly higher fracture strength than lithium disilicate in 0.5mm thickness, and significant different fracture strength in 1mm thickness. Most specimens (31 from 40) had been fractured in the restoration without involving tooth structure. Conclusion: the Cerasmart material could be considered a valid alternative to IPS e.max material.