Zyad G. Kinawy, Mohamed Abou El Yazeed, Wael Abd El Khalek, Mohamed S. Farag,

ABSTRACT
Objectives; Testing Different Surface Treatments On Repaired Composite Resin Filling And Reaching An Optimal Technique May Contribute To Increasing Success Rate Of Repair Which In Return Would Decrease The Need To Completely Replace The Filling, Thus Spearing The Child From Un-necessary Stress As Well As Saving Time And Money. Aim Of The Current Study Was To Compare The Influence Of Three Different Surface Treatments (Acid Etching, Diamond Stone, Sand-blasting) On The Bond Strength Of Aged-new Repaired Composite Filling (Filtek P60) Following Artificial Aging Procedures. Methods; 33 Discs Of Resin Composite Were Fabricated And Were Immersed In Distilled Water For 24 Hours. The Discs Were Then Divided Into 4 Subgroups And The Surface Treatments Were Done Consecutively (10 Acid Etch, 10 Diamond Stone, 10 Sand Blasting And 3 Control). Repair Was Then Done On The Treated Discs Then Were Thermocycled For 500 Cycles At 5�2/55�2�C Then All Were Stored In Distilled Water For 24 Hours. Shear Bond Strength Was Then Measured Using Universal Testing Machine By Loading The Samples At A Crosshead Speed Of 1 Mm/min. The Shear Force Was Applied To The Adhesive Interface Until Failure Occurred. Results; Sand Blasting Showed The Highest Mean Shear Bond Strength Values (37.18 MPa), Whereas Diamond Stone Followed Closely With A Value Of (36.55MPa). Those Groups Showed Significantly Higher Values Than Acid Etching Alone, Yet No Statistically Significant Difference Was Detected Between Them. There Was No Statistically Significant Difference Between The Acid Etching And The Control Groups. Both Showed The Lowest Means Shear Bond Strength (27.74 MPa) And (22.83 MPa) Respectively. Significance; Surface Treatments Before Repairing Composite Have A Positive Influence On Shear Bond Strength Of The Repaired Composite With Sand Blasting To Have The Highest Impact.