SHEAR BOND STRENGTH OF A RESIN COMPOSITE TO ENAMEL ETCHED WITH MALEICOR PHOSPHORIC-ACID

The purpose of this study was to evaluate the effect of 10 per cent ma leic and 37 per cent phosphoric acid on the shear bond strength of Z10 0 composite resin with Scotchbond Multi-Purpose adhesive to primary an d permanent tooth enamel. Four groups of 20 teeth each were establishe d: 1, permanent teeth, 10 per cent maleic acid etched for 15 seconds; 2, permanent teeth, 10 per cent maleic acid etched for 30 seconds; 3, permanent teeth, 37 per cent phosphoric acid etched for 15 seconds; 4, primary teeth, 10 per cent maleic acid etched for 15 seconds. Five te eth from each group were randomly assigned for SEM examination of the etched enamel surface. Scotchbond Multi-Purpose primer and adhesive we re applied to the etched enamel surface of the remaining 15 teeth and cured following the manufacturer's instructions. Z100 composite resin was placed in a nylon cylinder and cured for two 40 second intervals. Following thermocycling, the specimens were sheared on an universal te sting machine and debonded areas were examined visually with a stereo microscope and with SEM. The mean shear bond strengths in MPa were: 1, 17.00; 2, 14.58; 3, 14.66; 4, 11.18. ANOVA and Student-Newman-Keuls a nalyses revealed no statistically significant difference among the gro ups. SEM examination showed the majority of specimens fractured at the adhesive-resin interface.