Abdelrahman G. Ahmed , Cherif A. Mohsen And Shams W. Amgad,

Objective The Purpose Of This Study Was To Evaluate The Effect Of Ceramic Type And Thickness On The Microhardness And Degree Of Polymerization Of Dual Cure Resin Cement.

Materials and Methods: - Ninety Resin Cement Disc Shaped Samples (5 Mm In Diameter And 0.5 Mm In Thickness) Were Fabricated, Samples Were Divided According To Type Of Ceramic Plate That Was Used Into Three Groups (each Group N = 30), Group I : Resin Cement Discs Cured Through Lithium Disilicate Plate. ?IPS E.max Cad?, Group II : Resin Cement Discs Cured Through Hybrid Ceramic Plate ?Vita Enamic? And Group III : Resin Cement Discs Cured Through Zirconia Reinforced Lithium Silicate Plate ?Celtra Duo? . Each Group Was Subdivided Into 3 Sub Groups According To Ceramic Plate Thickness (each Subgroup N = 10), Sub Group I (0.5 Mm Thickness), Sub Group II (1 Mm Thickness) And Sub Group III (2 Mm Thickness) . Then Each Subgroup Was Divided Into Two Other Classes (5 Samples Each) According To Type Of Test (Microhardness, Degree Of Conversion (DC)) Test.samples Which Will Have Being Tested For Microhardness ,mounted In Wilson Micro-Hardness Tester Machine And Will Be Subjected To Static Load Of 50 G For 10 S By Means Of Indenter , A Calibrated Microscope (?50 Magnification) Will Be Used To Measure The Square Indentation. While For Degree Of Conversion Test, The Samples Were Examined By VERTEX 70v FTIR Spectrometer Equipment Operating At 16 Scans At 4cm-1 Resolution . By Using The Change In The Ratio Of The Aliphatic C=C To The Aromatic C=C Before And After Curing, DC Of Resin Was Calculated. The Data Was Collected, Tabulated And Statistically Analyzed. Result: It Was Found That The The Highest Microhardness Mean Value Was Recorded For Emax Groups (22.15?5.04) While The Lowest Microhardness Mean Value Was Recorded For Celtra Duo Groups Which Recorded (16.79?3.62). Besides, It Was Found That The Highest Microhardness Mean Value Was Recorded For Thickness 0.5 Mm Groups (23.62?2.94) While The Lowest Microhardness Mean Value Was Recorded For 2 Mm Groups Which Recorded (13.87?1.56). The Difference Between Groups Was Statistically Significant As Indicated By One Way ANOVA Test P Value < 0.05 For DC Test It Was Found That The Highest (DC) Mean Values Recorded For E-max (36.30?8.84) And The Lowest For Celtra Duo (21.44?8.61) And The Highest DC Mean Value Was Recorded For Thickness 0.5 Mm Groups (38.33?5.91) While The Lowest DC Mean Value Was Recorded For 2 Mm Groups Which Recorded (19.27?5.90).The Difference Between Groups Was Statistically Significant As Indicated By One Way ANOVA Test (P Value < 0.05) Conclusion: Ceramic Composition Affects Polymerization Of Dual?cured Resin Cement Due To Attenuation Of Light Reaching Cement. In This Study, Microhardness And Degree Of Polymerization Of Resin Cement Discs Cured Through Emax Plate Was Significantly Greater Than Vita Enamic Followed By Celtra Duo Plates. Ceramic Thickness Has A High Significant Effect On The Underlying Dual Cure Resin Cement MicroHardness Of The Dual Cure Resin Cement Are More Affected By The Thickness Of Ceramic Than By The Type Of Ceramic Used.