Mai Samir Omar, Mohsen H Abielhassan And Rasha Rafaat,

ABSTRACT
Objective: This Study Was Conducted To Evaluate The Effect Of Two Different Intensities Of A Light Curing Unit On The Marginal Sealing Of Direct Compound Posterior Bulk-fill Composite Restorations.

Materials and Methods: A Total Of 42 Freshly Extracted Human Premolars Free From Caries And Cracks Were Selected, They Were Divided Into Three Main Equal Groups ( N= 14), According To The Light Intensity Used In Curing; (L1): Conventional LED Curing ( 800 Mw/cm2), (L2): Light Amplified High Intensity LED For 5 Seconds, (L3) : Light Amplified High Intensity LED 10 Seconds . Each Main Group Is Divided Into 2 Subgroups According To Aging Period (T) Where (T1) Represents Storage For 24 Hours, (T2) Represents Storage For 3 Months In Artificial Saliva. Standard Proximal Box Cavities Were Prepared. The Dimensions Were 2�0.2 Mm For The Bucco-palatal Or Bucco-lingual Width. The Depth Was Standardized To Be 4 Mm And It Was 1.5mm From The Cervical Margin To The Pulpal Floor. Specimens Were Stored In Artificial Saliva Then They Were Immersed In 2% Methylene Blue Dye And Sectioned With Automated Diamond Saw. Stereomicroscope Was Used For Microleakage Analysis.

Results: Results Showed That The Least Microleakage Was In The Group Cured With High Intensity For 5 Sec. The Most Microleakage Was In The Group Cured With Conventional LED. Conclusion: It Was Concluded That High Intensity Curing System Improved The Marginal Sealing Of The Bulk- Fill Resin Composite And Light Curing Intensity Has A Direct Effect On The Cured Bulk-fill Resin Composite.