RESIN-MODIFIED GLASS-IONOMER CEMENTS - BONDING TO ENAMEL AND DENTIN

Objectives. This study was designed to investigate the effect of stora ge in water on bonding efficacy to enamel and dentin of four resin-mod ified (Dyract, DeTrey Dentsply; Fuji II LC, GC Dental Corp.; Photac Fi l, ESPE; Vitremer, 3M Dental Products), one conventional glass ionomer filling material (Ketac Fil, ESPE) and a resin composite system (Peka fill/Gluma bonding system, Bayer). The hypothesis was that water stora ge would lead to an adverse effect on bond strength of resin-modified glass ionomer cements to enamel and dentin. Methods. The shear bond st rength of each material was determined after storage periods of 24 h, 1 wk, 1 mon, 3 mon and 6 mon. The data were subjected to one-way ANOVA . Significant differences were determined by multiple comparison testi ng (significance level 5%). The failure modes of the debonded specimen s were analyzed with a dissecting microscope. Results. Shear bond stre ngths to enamel for Dyract, Photac Fil and Pekafill were 5.2 +/- 1.3, 9.9 +/- 1.6 and 17.0 +/- 2.3 MPa, irrespective of storage time (p > 0. 05). For Ketac Fil, the average shear bond strength between 1 wk and 6 mon was 4.5 +/- 1.7 MPa, the mean value for Fuji II LC between 24 h a nd 3 mon was 10.3 +/- 3.9 MPa and after 6 mon was 19.8 +/- 4.4 MPa, wh ile Vitremer showed increasing shear bond strengths between 24 h (2.4 +/- 0.8 MPa) and 1, 3 and 6 mon (13.8 +/- 4.3 MPa). Shear bond strengt hs to dentin were not adversely affected by storage throughout the 6 m on for Dyract (13.0 +/- 2.6 MPa), Fuji II LC (12.7 +/- 1.7 MPa) and Pe kafill (14.6 +/- 3.1 MPa), when tested by ANOVA (p > 0.05). Ketac Fil showed 4.9 +/- 1.2 MPa between 1 wk and 6 mon and lower shear bond str ength after 24 h. The average shear bond strengths up to 1 mon for Vit remer were 5.4 +/- 2.5 MPa (p > 0.05). However, at 3 and 6 mon immersi on in water, three specimens had loosened spontaneously. With Photac F il, no adhesion to dentin was registered. Most samples showed cohesive failure patterns in the restorative materials. Adhesive or mixed fail ures were registered only for Vitremer on dentin and enamel up to 1 wk and for Dyract on enamel. Significance. Long-term water storage gener ally had no adverse effect on bonding efficacy of resin-modified glass ionomer cements to dentin and enamel.