Abdullah Ahmed Hassanien, Zainab Diaa El-Din Soliman, Farid Sabry El-Askary And Mokhtar Nagy Ibrahim,

ABSTRACT
Continuous Exposure Of Dental Hard Tissues And Resin Based Restorative Materials To Various Beverages And Tooth Brushing Might Lead To Deterioration Of Surface Properties Of Materials Which Might Complicate Their Repair Potentiality Especially In Non-carious Lesions. This In Vitro Study Aimed To Evaluate The Shear Bond Strength Of RMGIC-to- RMGIC And RMGIC-to-Enamel Submitted To PH-cycling And Mechanical Tooth-brushing. Three Hundred And Twenty Resin Modified Glass Ionomer (Fuji II LC) And Bovine Enamel Specimens Were Submitted To Dynamic PH-cycling In Coca-Cola Soft Drink, Milk And Orange Juice. Control Specimens Were Prepared And Left In Distilled Water Without Submission To PH-cycling Protocol Or Mechanical Tooth-brushing. The PH-cycling Was Done Over A Period Of 1 Month That Involved Immersion In Different Beverages For 5 Minutes, 3x/day And Specimens Were Kept In Artificial Saliva Between Cycles. Mechanical Tooth-brushing Was Performed To The Specimens After The First And Third PH Cycles Daily For 2 Minutes Each, Using Tooth-brushing Simulating Device. Specimens Were Divided According To Surface Treatments (diamond Bur Grinding, 10% Polyacrylic Acid, Grinding/10% Polyacrylic Acid And No-treatment) Into 4 Subgroups (n=10). Shear Bond Strength Test Was Performed After 24 Hours. The Surface Morphology Of Specimens Subjected To PH-cycling And Mechanical Tooth-brushing Was Analyzed Using Scanning Electron Microscope. Results Showed That With RMGIC, The Highest SBS Was Recorded With The Grinding/10%PAA Groups While The Lowest With The No-treatment Group. For The Enamel; Highest SBS Was With 10%PAA And The Lowest With Surface Grinding. Shear Bond Strength Of RMGIC-to-RMGIC Or RMGIC-to-enamel Is Influenced By The Different Surface Treatments Used.