Angham Ibrahim El-Gendy, Mohamed Farag Ayad And Amany Mohammed Korsel,

ABSTRACT


Purpose: To Evaluate The Fatigue Resistance Of High Translucent Zirconia And Hybrid Ceramic Posterior Occlusal Veneer.

Materials and Methods: Forty Freshly Extracted Human Molars Were Received Standardized Tooth Preparations Replicating A Worn Occlusal Table By Using A Diamond Saw By Removing All Coronal Tooth Structure 4 Mm Occlusal To The CEJs Leaving Exposed Dentin Centrally And Peripheral Enamel. Intra-enamel Indexing Notches Were Created Proximally. The Specimens Were Divided Into 2 Groups Based On Restorative Materials Each Group Included Twenty Teeth For Each Group. Group I: High Translucent Zirconia (Bruxzir Anterior), Group II: Polymer Infiltrated Ceramic (Vita Enamic). The Restoration Thickness Was 1 Mm At The Fossa And 1.5 Mm At The Cusp Tip. The Specimens Were Cemented By Self-etch Resin Cement (Panavia F2.0). Half Of The Specimens Of Each Group(10 Specimen) Were Subjected To Fracture Resistance Test While The Other Half Subjected To Thermocycling (15000 Cycles, 5-55 C, 30 Sec Dwell Time) And Chewing Simulator With A Load 150 N Which Was Applied For 600,000 Cycles To Simulate 2.5 Years With A Loading Frequency 6 HZ. Specimens That Survived Cyclic Loading Were Loaded Until Failure, To Calculate The Residual Fracture Strength After Fatigue. Mean Values For Each Group Were Calculated, And Differences Between The Groups Were Tested For Statistical Significance By Use Of 2-way Analysis Of Variance (ANOVA).

Results: Both Material And Fatigue Test Had Significant Effect On The Fracture Resistance Where (P-value<0.001). According To The Material Type; P-value Was High Significante As The Bruxzir Anterior Had A Higher Mean Of Fracture Resistance Than The Vita Enamic. According To The Fatigue Test For Bruxzir Anterior ,the P-value Was High Significant As The Mean Of The Initial Fracture Resistance Was 2240.60� 139.90 Which Is Higher Than The Mean Of The Specimen After Subjected To Fatigue Test 2019.88 � 132.29. For The Vita Enamic The P-value Was High Significant That The Mean Of The Initial Fracture Resistance Was 744.58 �99.23 Which Is Higher Than The Mean Of The Specimen After Subjected To Fatigue Test 596.45 �81.13. The Coefficient Of Variation Showed That For Bruxzir Anterior The Specimens Lost About 22 % Of Their Initial Fracture Resistance After They Were Subjected To Fatigue While The Vita Enamic Specimens Lost About 19 % Of Their Initial Fracture Resistance. Conclusion: Within Limitations Of This Study, High Translucent Zirconia Posterior Occlusal Veneers Can Resist Cyclic Loading That Represent Several Years In Patient Mouth, The Percentage Of The Loss In The Initial Fracture Resistance Of Both Material After Subjected To Chewing Simulator Was Approximated To Each Other, However More Researches Are Required To Prove The Use Of Polymer Infiltrated Ceramic As Posterior Occlusal Veneers.