Mona Mahmoud Mohamed, Mai Mahmoud Yousry And Amir Hafez Ibrahim,

ABSTRACT
This Study Was Conducted To Evaluate The Effect Of Curing Direction (occlusal And Transtooth Polymerization), And Curing Time, As Well As The Influence Of Remaining Wall Thickness, As Reflected By Cavity Width On The Depth Of Cure Of Bulk-fill Resin Composite Proximal Restorations.

Materials and Methods: A Total Of 40 Sound Human Maxillary Premolar Teeth Were Used In This Study. The Occluso-gingival Height Of Teeth Was Of A Minimum Of 4.3mm And The Bucco-lingual Dimension Of The Selected Teeth Was 8.6-10.5 Mm; All Dimensions Were Measured Using A Digital Caliper. The Teeth Were Divided Into 2 Groups Of 20 Each According To The Curing Direction; Either Occlusal Curing According To Manufacturer?s Instructions, Transtooth Curing From The Buccal And Lingual Direction. Standardized Box Shaped Cavities Were Prepared On Proximal Surfaces Of Each Tooth Having Occluso-gingival Depth Of 4 Mm, Axial Wall Depth 1.5 Mm And 3 Mm Bucco-lingual Width. All Prepared Cavities Were Restored Using X-tra Fil Bulk Fill Resin Composite Placed In One 4 Mm Increment And Then Cured. Each Specimen Was Then Sectioned In A Mesio-distal Direction And Each Half Was Poured In Acrylic Resin Block. Then, Vickers Hardness Number (VHN) Was Determined On The Top And The Bottom Surfaces (0.1 From Occlusal Surface And 0.1 Mm From Gingival Wall) Using Digital Display Vickers Micro-hardness Tester. Two Way ANOVA Was Used To Study The Effect Of Different Curing Direction.

Results: The Tested Bulk-fill Resin Composite (X-tra Fil) Achieved At Least 80% Depth Of Cure Value At 4mm Thickness With Irradiation Time 10 Seconds. Regarding The Curing Direction, A Non-significant Difference In Depth Of Cure Between Occlusal And Transtooth Curing Was Revealed (P>0.5). The Bottom Microhardness Also Showed A Non-significant Difference Between Curing Directions (P>0.5). While For Top Microhardness, Occlusal Curing Showed Significantly Higher Value Than Transtooth Curing (P>0.5). Conclusion: An Acceptable Depth Of Cure Could Be Achieved With 4mm Increment Of Bulk-fill Resin Composite.