Esraa Mohamed Hany, Hesham Katamish And Carl Hany Halim,

ABSTRACT
The Principle Aim Of This Investigation Was To Evaluate The Effect Of Preparation Design Of Tooth And Two CAD/CAM Ceramic Materials On Marginal Adaptation And Fracture Resistance Of Laminate Veneers Restorations. Thirty Extracted Human Sound Maxillary Central Incisors Were Selected And Divided Into Two Main Groups According To The Type Of The CAD/CAM Ceramic Material Used: Group I: IPS Emax CAD And Group II: Vita Enamic. Each Group Was Then Sub-divided Into Three Equal Sub-groups According To Different Preparation Designs For Laminate Veneer Restoration. Specimens Of Subgroup (A) Were Prepared With A Featheredge Design, Specimens Of Subgroup (B) Were Prepared With Butt-joint Design And Specimens Of Subgroup (C) Were Prepared With An Incisal Wrap Around Design. Marginal Adaptation Was Evaluated Using USB Digital Microscope With A Built-in Camera Connected To A Computer Using A Fixed Magnification Of 45X. A Digital Image Software Was Used To Measure And Evaluate Gap Width. Statistical Analysis Was Performed Using Two-way ANOVA And Tukey?s Post-hoc Tests. While Fracture Resistance Was Tested Using The Universal Testing Machine With Load Cell 5 KN. Compressive Mode Of Loading Was Applied Incisally At 135� And Cross Head Speed 1mm/min. It Was Found That E.max In Butt Subgroup Recorded Statistically Significant (P<0.05) Highest Fracture Resistance Mean Value (387.8�52.4 N) Followed By E.max In Feather Subgroup (382.6�66.4 N), Vita Enamic In Feather Subgroup (332.3�57.1 N) Then Vita Enamic In Wrap Subgroup (309.53�32.47 N) And E.max In Wrap Subgroup (263.20�27.04 N) While Vita Enamic In Butt Subgroup Recorded Statistically Significant (P<0.05) Lowest Fracture Resistance Mean Value (258.37�46.26 N) As Indicated By One-way ANOVA Test.