Effects of tooth-conditioning agents on bond strength of a resin-modified glass–ionomer sealant to enamel

Objectives. The purpose of this study was to evaluate the effects of tooth-conditioning agents on bond strength of resin-modified glass–ionomer sealant (Fuji III LC) to bovine enamel as well as on dissolution of calcium ions from the bovine enamel surfaces. Methods. The enamel surfaces of bovine lower incisors were treated with 10 and 20% polyacrylic acid, 12% citric acid and 35% phosphoric acid for 20 s. Fuji III LC was applied to the etched enamel surfaces, and the shear bond strength of each specimen was measured using an Instron Universal Testing Instrument. The amounts of calcium ions dissolved from the treated enamel surfaces were also measured using a polarized Zeeman atomic absorptiometer. Results. In specimens pretreated with distilled water, 10% polyacrylic acid, 20% polyacrylic acid, 12% citric acid and 35% phosphoric acid, the mean values of shear bond strength were 5.5, 12.5, 15.2, 15.2 and 15.1 MPa, respectively, and the amounts of Ca2+ dissolved from the enamel surfaces were 5.6, 41.4, 88.5, 131.6 and 588.3 μg/cm2, respectively. Conclusions. The adhesion of a resin-modified glass–ionomer sealant to bovine enamel was significantly improved by the use of tooth-conditioning agents. Especially, treatment of an enamel surface with 20% polyacrylic acid results in good shear both strength and relatively small degree of enamel erosion.