Influence of environmental conditions on bond strength of a resin-modified glass ionomer

To investigate the influence of temperature and relative humidity (RH) on the dentin bond strength of a resin-modified glass ionomer cement (Fuji II LC) and to evaluate the bonding efficacy of dentin primer.

Four environmental conditions: (A) 25 +/- 1 degrees C, 50 +/- 5% RH, (B) 25 +/- 1 degrees C, 95 +/- 5% RH, (C) 37 +/- 1 degrees C, 50 +/- 5% RH, (D) 37 +/- 1 degrees C, 95 +/- 5% RH, were used to make the specimens. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were ground on wet #600 SiC paper to expose dentin. Dentin Conditioner and OptiBond Prime were employed as treatment agents. After treating the dentin surface, the cement was condensed into a vinyl mold (4 x 2 mm) placed on the dentin and light cured. Ten samples per test group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Duncan test (P < 0.05) were done.

The dentin bond strengths of the no-conditioning group and Dentin Conditioner treatment group increased with increasing temperature but were not influenced by RH. With the use of the dentin primer, increased bond strengths and no influence of environmental conditions were observed. These data suggest the efficacy of employing dentin primer for application of the resin-modified glass ionomer cement regardless of temperature or RH.