Mostafa M. Hussein And Cherif A.Mohsen,

ABSTRACT
Objective: The Purpose Of This In Vitro Study Will Evaluate Marginal Gap Of Endocrowns Retained Bridges Replacing Missing Lower Second Molar Will Done By Two Different Designs From Monolithic Zirconia.Material And Method: Twenty Bridges Designed From Monolithic Zirconia. Specimens Will Be Divided Into Two Groups, Each Of These Groups Contains 10 Samples, The Firstgroup Represents Endocrown Endocrown Retained, And Second Group Endocrown Retained Bridges. The Marginal Gap For The Buccal, Lingual, Proximal And Connector Area Were Measured .scan Electron Microscope Were Used. Universal Testing Machine Was Used To Detect Fracture Resistance For All Samples.

Results: Data Analysis Was Performed By Student T-tests To Detect Significancebetween Groups. One Way Analysis Of Variance ANOVA Test Followed By Pair-wise Newman-Keuls Was Used To Detect Significancebetween Sites. Statistical Analysis Was Performed Using Graph Pad Prism-4 Statistics Software For Windows. P Values < 0.05 Are Considered To Be Statistically Significantin All Tests. Marginal Gap Results Measured In Micron (?m) For Both Designs At Different Sites. It Was Found That Endocrown Endocrown Retained Recorded Higher Marginal Gap Mean Value Than Endocrown Retained Bridges And This Was Statistically Non-significant (p > 0.05)

Conclusions: Fracture Resistance And Marginal Gap Of Endocrowns Retained Bridges With Two Different Designs Were Be Accepted.