Effect of conditioning limes on resin-modified gloss-ionomer bonding

Purpose: To evaluate in vitro the effect of different polyacrylic acid cond itioning times on the shear bond strength of a resin-modified glass-ionomer bonded either to enamel to dentin surfaces. Materials and Methods: 36 flat enamel and 36 dentin bond sites were prepared to 600 grit on human incisor s. Five groups (n= 6 per group) for each substrate (enamel or dentin) were conditioned using 20% polyacrylic acid and 3% aluminum chloride for either 10, 20, 40, 80, or 160 s before bonding with the resin-modified glass-ionom er. A non-conditioning group per substrate group was used as a control. A h ybrid composite was placed in two increments in a 3 mm diameter matrix on t he treated surfaces. The specimens were stored for 4 weeks in distilled wat er at 37 degrees C. Shear bond strengths were determined using an Instron t esting machine with a load rate of 0.5 mm/min. Additionally, 15 enamel and 15 dentin samples were tested with a profilometer to quantify changes in su rface roughness during the different conditioning times. Results: Dentin sh ear bond strength values were not significantly different among the differe nt groups, including the unconditioned control group. For enamel, the uncon ditioned group was significantly weaker than any of the conditioned groups. No significant differences (P> 0.05) were found among the conditioned enam el specimens. No significant differences in surface roughness were found fo r either enamel or dentin.