Mohamed G. Hussein And Cherif A. Mohsen,

ABSTRACT
Objective: The Purpose Of This Study Was To Investigate Microleakage Ofdifferent Lithium Disili-cate Occlusal Veneers Designs With Different Tooth Preparations.Material And Method: Fifty-six Extracted Human Mandibular Molars Were Collected With Rela-tively Comparable Size And Standardization Done By Diamond Saw And It Will Receive .6mm Lithium Disilicate Occlusal Veneers. Specimens Will Be Divided Into Two Main Groups, Each Of These Groups Contains 28 Samples (group A&B), The Firstgroup Represents Occlusal Veneers With 1.0 Ml With Radial Shoulder Finishline Design Includes Axial Surfaces For A2 Ml Length, While The Second Grou-prepresents Occlusal Veneers Preparation Without Finishline. Each Main Group Will Be Subdivided Into 2 Subtypes Groups (A1, A2, B1, B2), Each Subtype Group Contains 14 Samples, The Firstsubtype Group Will Receive A Buccal Groove, While The Second Subgroup Will Be Without Grooves. Each Sub-group Will Be Divided Into 2 Classes (7samples) According To The Type Of Test It Will Be Subjected To: Microleakage, Bond Strength.

Results: Microleakage Results Measured In Millimeter(mm) Showing Mean Values And Standard Deviations(SD) For All Veneers Design Groups As Function Of Preparation Designs Are Summarized In Table(3). It Was Found That There Was No Dye Penetration Recorded For All Preparation Design Groups.

Conclusions: All Tested Occlusal Veneer Designs Luted In Acorrect Procedures With A Standardized Adhesive System Showed Nearly No Microleakage