Sally M. El Shennawy, Tamer A. Hamza And Ahmed Hassanien Khalil,

ABSTRACT
Statement Of Problem: Recently, Hybrid Ceramics Introduced Having Advantages Of Being Easily Processed And Time Saving. However, There Are Still Concerns About Marginal Accuracy With Different Finish Line Curvatures.

Purpose: The Purpose Of This In Vitro Study Was To Evaluate The Effect Of Two Finish Line Curvatures And Types Of Ceramic On Margin Fit Of Monolithic Restorations. Methodology: A Total Of 20 Monolithic Crowns Was Fabricated For This Thesis And Was Divided Into Two Groups According To Ceramics (Polymer Infiltrated Ceramics, Lithium Disilicate), And Each Group Will Be Further Subdivided Into Two Groups According To Finish Line Curvature (0mm And 3mm).The Crowns Was Placed On The Stainless Steel Dies And The Vertical Marginal Fit Was Evaluated With Sterio Digital Microscope At An Original Magnification Of X 30. The Results Were Tabulated And Statistically Analyzed With Using Kolmogorov-Smirnov And Shapiro-Wilk Tests. Kruskal-Wallis Test Was Used To Compare Between The Two Ceramic Types. Dunn?s Test Was Used For Pair-wise Comparisons When Kruskal-Wallis Test Is Significant. Mann-Whitney U Test Was Used To Compare Between The Two Finish Line Types.

Results: With Straight Finish Line; Lithium Disilicate Showed Statistically Significantly Higher Mean Marginal Gap Distance Than Polymer Infiltrated Ceramics. With Curved Finish Line; There Was No Statistically Significant Difference Between The Two Ceramic Types. In Addition, With Both Ceramic Types; There Was No Statistically Significant Difference Between The Two Finish Line Types.

Conclusions: Under The Circumstances Of This In Vitro Study, It Can Be Concluded That; The Polymer Infiltrated Ceramics Hybrid Restorations Had Superior Marginal Fit Than Lithium Disilicate And The Finish Line Curvatures Did Not Affect The Marginal Fit Of Tested Restorations. Clinical Implications: In The Light Of The Present Study; All Tested Samples Produced Marginal Fit Within Acceptable Range, So Can Be Used Clinically Providing Satisfactory Results.