الفهرس 
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Abstract
SUMMARY
Two different preparations were done on teeth number 23 of the typodont model, one palatal and one labial for each design. Twenty epoxy models were duplicated resembling upper central incisors and canines, 10 epoxy models for each design.
Twenty cantilever all ceramic resin bonded fixed dental prostheses were (RBFDPs) fabricated to replace a missing maxillary lateral incisor.
The prostheses were divided into two groups according to the site of the retainer:
i) Palatal veneer retained fixed dental prosthesis (n=10).
ii) Labial veneer retained fixed dental prosthesis (n=10).
All ceramic fixed dental prostheses were designed using Exocad software and fabricated from lithium disilicate using heat pressed technique. Then the prostheses were bonded to their corresponding epoxy resin model using dual cure resin.
Fracture resistance test were performed on all specimens after thermomechanical aging with chewing simulator for 150,000 mechanical fatigue cycles of 50 N loads. Data were collected, tabulated and statistically analyzed through paired t- test.
Summary •
It was found that the fracture resistance mean±SD values recorded for the palatal veneer group were (204.89±27.28 N) with the minimum value (163.21 N) and maximum value (283.52N). Meanwhile, the fracture resistance mean±SD values recorded for the labial veneer group were (176.21±40.57 N) with the minimum value (121.84 N) and maximum value (253.41N).
It was found that the palatal veneer group recorded statistically non-significant (p= 0.0903>0.05) higher mean value (204.89±27.28 N) than the labial veneer group mean value (176.21±40.57 N) as indicated by paired t-test.
For the palatal veneer group, failure analysis predominantly revealed die fracture (50%), the retainer + abutment fracture was recorded in (40%) mean while minority of samples recorded Connector fracture (10%).
For the labial veneer group, two samples (20%) failed during fatigue testing while in all the remaining samples (80%) retainer fracture was observed.
• Summary
Within the limitation of this study, the following conclusions were drawn:
• Both palatal and labial VRFDP can provide a viable treatment option in case of maxillary lateral incisor loss.
• from the failure mode observed it could be assumed that labial VRFDP would be a preferred treatment modality since the failed restorations may be replaced as opposed to 50% chance of abutment fracture observed within the palatal retained group.