الفهرس 
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Abstract
STATEMENT OF PROBLEM: The precision of CAD milled restorations, is affected by the acquired images of intra-oral scanners, which in turn is influenced by the scanning technology, and whether powder is applied or not. In addition, in the case of ultra-thin veneers, the preparation thickness is a major factor in obtaining accurate marginal adaptation, especially with the introduction of new ceramic materials such as the zirconia reinforced lithium silicate.
AIM OF THE STUDY: The purpose of the present study was to assess the marginal adaptation and marginal chipping of ultra-thin veneers made in two thicknesses (0.3mm & 0.5mm), by two ceramic materials (VITA Suprinity, IPS E.max), using two intra-oral scanners (Bluecam, Omnicam). Furthermore, specimens were subjected to dynamic loading for fatigue analysis.
MATERIALS & METHODS: Impressions of the prototype were made after the teeth preparation, to obtain the specimens that the veneers will be cemented on. The prototype was scanned directly using Omnicam scanner, and after application of opti-spray for bluecam scanning. The veneer was placed steadily under the microscope, and a photo of each veneer was captured from the labial side with 30 X magnification, all surfaces were visible for chipping measurements. The edge distance was measured in mm from the center of the indentation location to the edge using the previously described stereoscopic microscope system. All veneers were adapted in its place one on each duplicated epoxy sample. Hand held digital microscope (Dino Lite), was used to take photos of the veneers. After cementation, marginal adaptation measurements were done on each side (Incisal margin, Mesial margin, Distal margin, and Cervical margin) by taking 50 points to be measured from restoration margin to tooth margin after curing of resin cement. And the data was collected for statistical analysis. Each specimen (veneer cemented on epoxy duplicate) was loaded from the incisal direction vertically parallel to the long axis of the tooth. 49 N load was applied, and test was repeated for 120,000 cycles to simulate a 1-year chewing condition.
RESULTS: The result of the present study revealed that, Bluecam group recorded statistically significant (P<0.05) higher marginal gap than Omnicam group, VITA SUPRINITY group recorded statistically non-significant (P>0.05) higher marginal gap than E.max group. Totally it was found that 0.3mm thick group recorded statistically significant (P<0.05) higher marginal gap than 0.5mm thick group. Totally it was found that after cementation, marginal gap was statistically significant (P<0.05) higher than before cementation. According to Marginal chipping: It was found that Bluecam group recorded statistically non-significant (P>0.05) higher chipping area than OmniCam group. It was found that E.max group recorded statistically non-significant (P>0.05) higher chipping area than VITA Suprinity group. It was concluded that 0.3 mm thick group recorded statistically significant (P<0.05) higher chipping area than 0.5mm thick group.