Abstract
To evaluate the microshear bond strength of self etch and etch & rinse adhesives of nanofilled composite on enamel substrates after fluoride application. Materials and Methods: Forty Enamel samples were obtained from human premolars and randomly divided into 2 groups (n = 10) according to enamel substrates treatment first group samples are painted with fluoride varnish for 20 min and stored in artificial saliva for 24 hours, then divided into 2 subdivisions : first subdivision is treated with etch & rinse adhesive then. 2nd subdivision samples are treated with self etch adhesive. The second group divided into 2 subdivision : first subdivision are treated with etch & rinse adhesive. 2nd subdivision samples are treated with self etch adhesive. All prepared samples, Prior to adhesive curing, a hollow cylinder (2.0 mm height/0.75mm internal diameter) was placed on the treated surfaces. A nanofilled resin composite was then inserted into the tube and cured. After artificial saliva storage for 24 hrs, the tube was removed and microshear bond strength was determined in a universal testing machine at a crosshead speed of 0.5 mm/min. Results: The mean and standard deviation values of micro-shear bond strength were 15.9 +/- 4 MPa and 9.7 +/- 3.8 MPa for normal and fluoridated enamel, respectively. Normal enamel showed statistically significantly higher mean micro-shear bond strength than fluoridated enamel. Conclusions: The microshear bond strength decrease in cases of recently fluoridated enamel.