Effect of surface treatment and cement maturation on the bond strength of resin-modified glass lonomers to dentin

This study investigated the effect of surface treatment and cement maturation on the bond strength of resin-modified glass ionomer cements (RMGICs) to dentin. Forty-two freshly extracted premolars were embedded and horizontally sectioned at a level 2 mm from the central fossa to obtain a flat dentin surface. The premolars were randomly divided into three groups of 14 teeth and treated as follows: Group 1 (control)-no surface treatment, Group 2-conditioned with 20% polyacrylic acid for 10 seconds and Group 3-etched with 37% phosphoric acid for 15 seconds. RMGIC (Fuji II LC, GC) columns (3 mm diameter; 2 mm high) were applied to the dentin surface and shear bond testing was carried out after one week (n=7) and one month (n=7) storage in distilled water at 37degreesC using an Instron Universal testing machine with a cross-head speed of 0.6 mm/minute. The failure mode was examined at 40x magnification and scored with imaging software. The results were analyzed using ANOVA/Scheffe's post-hoc test and Kruskal-Wallis/Mann-Whitney test at a significance level of 0.05. The effect of surface treatment on shear bond strength to dentin was time dependent. Mean strengths ranged from 3.16 to 5.81 MPa at one week and 5.00 to 14.95 MPa at one month. Although no significant difference in strengths was observed among the groups at one week, significant differences (Group 2 > Group 1 > Group 3) were detected at one month. At one month, conditioned and untreated specimens exhibited significantly less adhesive failure than etched specimens.