Effect of three veneering techniques on the marginal accuracy and fracture resistance of zirconia base fixed restorations : In-vitro study / Menatallah Mohamed Elhoteiby ; Supervised Hesham Katamish , Mona Attia ELagroudi , Maha Ahmed Taymour

Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Prosthodontics

This in vitro study was conducted to compare the effect of three different veneering techniques on the marginal accuracy and fracture resistance of zirconia restorations, In addition to studying the effect of coping design on the same two previous variables. A stainless steel die simulating a prepared mandibular first molar was machine milled with convergence angle 6 {u02DA}, with cusp angle 135 {u02DA}, 1 mm finish line thickness and anatomic occlusal surface. According to sample size calculation a total of forty two Zirconia crowns were constructed by CAD/CAM technology and divided into two equal groups according to coping design and six equal sub-groups according to veneering technique used: Group A: zirconia collar crowns(21 crowns) Sub-group AI: veneering by layering technique (n=7). Sub-group AII: veneering by press on technique (n=7). Sub-group AIII: veneering with bi-layering technique (n=7) Group B:zirconia collar less crowns(21 crowns) Sub-group BI: veneering by layering technique (n=7). Sub-group BII: veneering by press on technique (n=7). Sub-group BIII: veneering with bi-layering technique (n=7). e-maxceram mix was applied to the zirconia copings and fired then glazed In the layering veneering technique. In the press on veneering technique a specially constructed CAD wax was milled corresponding to each zirconia coping. This CAD wax was sprued, invested , preheated and pressed in the furnace. While, in the bi-layering technique the same steps of press on were done except for application of e-max ceram layering ceramic in the cut back area

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