Saher M. Elsharkawy, Shaymaa I. Habib And Randa Elsalawy,

ABSTRACT
Objective: This Study Was Performed To Evaluate The Effect Of Casein Phosphopeptide Amorphous Calcium Phosphate With Fluoride (CPP-ACP-F) Remineralizing Surface Treatment And Its Application Time On The Micro-shear Bond Strength Of Resin Composite Restorative Material To Demineralized Dentin Using A Self-etch Adhesive. Methodology: A Total Of Ninety Freshly Extracted Sound Premolars Were Used. PH Cycling Was Carried Out For 14 Days To Produce An Artificially Affected Dentin. The Remineralizing Agent Was Applied To The Pretreated Groups For 1min And 3min. A Nano Filled Resin Composite Was Used (Filtek Z350 Universal Resin Composite) With One Type Of Self-etch Adhesive System (Scotchbond Universal Adhesive). For The Micro-shear Bond Strength Test, Each Tooth Was Mounted In A Readymade Mold Filled With Cold Cure Acrylic Resin, And Translucent Micro-catheters With An Internal Diameter Of 0.9 Mm Were Utilized For Composite Packing On The Dentin Surface. The Durability Of The Micro-shear Bond Strength In Artificial Saliva Of The Resin Composite Restorative Material To Dentin Was Investigated After A Period Of 24 Hours And 3 Months Aging. The Bonded Specimens Were Subjected To A Shear Load Applied To The Interface With A Thin Wire Loop At A Cross Head Speed Of 0.5 Mm/min Until Fracture. The Load Required For Debonding Was Recorded In Newton. Analysis Of The Failure Mode Was Observed Using A Stereo-microscope And Digital Microscope.

Results: The Control Group Revealed A Significantly Higher Mean �-shear Bond Strength (�-SBS) Compared To The Pretreated Groups. No Statistically Significance Was Found Between The Pretreated Groups. However, After Storage In Artificial Saliva For 3months, A Non-statistically Significant Decrease In The �-SBS Values Was Recorded In Both The Control And The Pretreated Group For 3 Min. After 24 Hours Storage In The Artificial Saliva, The Control Group Showed The Highest Adhesive And Mixed Failure Percentage (40%). However, The Pretreated Groups Showed The Highest Adhesive Failure (53.3% And 46.7% Respectively). Cohesive Failure Was Reported As The Least Mode Of Failure Percentage In Both Groups (6.7% And 13.3% Respectively). It Was Also Observed That A Non-statistically Significant Difference Existed Between All Tested Groups After 24 Hours Storage. After 3 Months Storage In Artificial Saliva, The Control Group Showed The Highest Percentage Of Adhesive Failure (53.3%). However, The Pretreated Groups Had The Highest Percentage Of Adhesive Failure (66.7% And 60% Respectively) And The Least Percentage Was Recorded As Of Cohesive Failure (6.7% And 13.3% Respectively). A Non-statistically Significant Difference Was Noted In The Failure Mode Between All Tested Groups. Regarding The Effect Of Aging Time, Results Similarly Revealed No Significant Difference In The Mode Of Failure Percentage Between 24 Hours And 3 Months In All The Investigated Groups (control And Pretreated).

Conclusions: Although Pretreatment Of Dentin Surface With CPP-ACP-F Remineralizing Agent Could Decrease The �-SBS Of Resin Composite To Demineralized Dentin Using All In One Adhesive, The Reduced Values Are Still Within The Clinically Acceptable Level. Aging Time Play A Role On The Stability Of The Bond Strength Of Resin Composite To Demineralized Dentin Surface.