Aly Elkady, Karim Aboubakr And Amina Zaki,

ABSTRACT
Statement Of Problem: Zirconia Reinforced Lithium Silicate Ceramics Have Been Introduced As An Alternative To Lithium Disilicate Ceramics. Manufacturers Market The Novel Material As A More Translucent And Stronger Ceramic That Was Indicated For Similar Applications. Scarcity Of Published Literature Regarding The Color And Translucency Of The Material Warrants An Investigation To Better Predict The Clinical Outcome Of Dental Restorations.

Purpose: Evaluation Of The Translucency Parameters (TP) And Color Difference From Standard (?E) Of Two Machinable Glass Ceramic Materials Namely IPS E.max CAD (EM) And Vita Suprinity PC (VS); Constructed Of Three Different Thicknesses That Represent The Incisal, Middle And Cervical Regions Of A Laminate Veneer Restoration.

Materials and Methods: Blocks Of IPS E.max CAD And Vita Suprinity PC (A3 Shade HT Opacity) Were Sectioned In A Transverse Orientation To Obtain Twenty-one Specimens Of Each Material. Each Group Contained Three Subgroups Of Seven Specimens According To The Thickness Approximately 0.3, 0.6, And 0.9 Mm (� 0.05 Mm) Thicknesses. All Specimens Were Subjected To Spectrophotometric Analysis Before And After Glazing Over A White Background And Over A Black Background To Determine Their Translucency Parameters (TP). Vita Lumin Shade Guide A3 Tab Was Used As A Reference Color Measurement For Color Difference Calculations (?E). Repeated Measures Analysis Of Variance (ANOVA) Was Used To Study The Effect Of Ceramic Type, Thickness, Glazing And Their Interaction On Mean TP And Color Changes. Bonferroni?s Post-hoc Test Was Used For Pair-wise Comparisons When ANOVA Test Is Significant.

Results: All Specimens Showed A Statistically Significant Decrease In TP And A Statistically Significant Increase In ?E After Glazing. The Thicker The Specimen The Closer It Matched The Shade Reference And The Lower Its Translucency. IPS E.max CAD Specimens Demonstrated Lower Mean TP Values And Higher Mean ?E Values. Conclusion: Regardless Of The Thickness Of The Material, IPS E.max CAD Specimens Were Significantly More Translucent That Vita Suprinity Specimens. Regardless Of The Material Used, The 0.9 Mm Thickness Specimens Showed The Lowest ?E And TP Values Followed By The 0.6 Mm Thickness Specimens Then The 0.3 Mm Thickness Specimens. Regardless Of Material And The Thickness, Glazed Specimens Showed A Statistically Significant Lower Translucency Than Unglazed Specimens. Vita Suprinity Showed A Lower Mean Color Difference Compared To The Reference Shade Tab Regardless Of The Background Or Thickness Of The Specimen. Clinical Implications: The Use Of Vita Suprinity For Laminate Veneer Restorations Would Allow The Clinician To Achieve The Desired Shade While Maintaining Conservatism. The Use Of Vita Suprinity Is Recommended In Clinical Situations Where Color Masking Is Important And Working Space Is Limited Which Would Expand The Range Of Indicated Clinical Situations Where Laminate Veneers Are Advocated.