الفهرس 
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Abstract
Statement of Problem: Studies have established different laminate veneer designs for treatment of severely eroded anterior teeth, however fracture strength of these different laminate veneer designs (Bilaminar and V-shape) fabricated with different types of ceramic is unknown as there is lack of study. Aim of the Study: To evaluate the fracture strength of two different laminate veneer designs (Bilaminar and V- shape) using two different ceramic materials (IPS e.max press and Metoxit Z-CAD zirconia ceramic). Materials and Methods: Forty intact human maxillary central incisors were selected, they were reduced 2 mm incisally and 1 mm palatally to simulate erosion, then classified in to 2 main groups (n=20) according to laminate veneer design; (B) bilaminar veneer and (V) v-shape veneer. Each main group was further subdivided into 2 subgroups (n=10) according to type of ceramic used; (E) e.max press ceramic, and (z) zirconia ceramic. Preparation for group (B) was done with facial reduction 0.3 mm in the cervical third and 0.5 mm in the middle and incisal third following the cervical curvature and extending mesially and distally to the mesiobuccal and distobuccal line angles, , and palatal reduction was only establishing 0.5 mm chamfer finish line 0.5 mm incisal to the CEJ and extending from mesiopalatal to distopalatal line angle, preparation for group (V) was done at the same way with removing any facial undercuts. Veneers were fabricated and cemented to their corresponding abutments. All specimens were supjected to fracture strength test using universal testing machine, data were collected and analyzed using (t) test and two way ANOVA test. Results: It showed a statistical significant difference between the two materials in the same design as zirconia showed higher fracture strength compared to e.max press ceramic. On the other hand, it showed no statistical significance between the two designs with the same materials. Conclusion: 1) The design of laminate veneer ( bilaminar or V- shaped) has no effect on the fracture strength of the two ceramic materials used in this study. 2) Zirconia ceramic, despite the veneer design showed higher fracture strength compared to e.max press ceramic. Clinical significance: 1) In eroded teeth, the two designs could be used successfully as they are more conservative than a full crown preparation. 2) In cases where un entruptted path of insertion could be obtained, V- shape veneers is recommended. 3) In cases where path of insertion could not be obtained, bilaminar design is recommended.