BOND STRENGTH OF GLASS-HYBRID AND GLASS-IONOMER MATERIALS TO SOUND AND CARIES-AFFECTED PRIMARY DENTINE

Less invasive caries management is recommended for primary dentition, but little is known about how primary dentine demineralisation affects the adhesion of new formulations of glass-ionomer (GI) restorative materials. The study aimed to evaluate the microtensile bond strength (µTBS) of a glass-hybrid (GH), high-viscosity (HV-) and resin-modified (RM-) GI restoratives to sound (SD) and caries-affected (CAD) primary dentine. Occlusal cavities were prepared in 60 primary molars and randomly divided into SD and CAD. Teeth were divided into subgroups (n=6) and restored with a GH (Equia Forte HT), two HV-GI (Equia Fill, Ketac Molar), and two RM-GI (Fuji II LC, Photac Fill) materials. After thermal aging, µTBS and mode of failure were analysed. The overall bond strength was higher for SD than for CAD (p<0.05, Mann-Whitney test). For both SD and CAD, Equia Forte and Equia Fill showed higher µTBS compared to other GI restoratives (p<0.05, Kruskal-Wallis test). The most frequent mode of failure was adhesive, followed by mixed failure, with no differences between the subgroups (p>0.05, chi-square test). Novel restorative formulations are likely to provide better bonding properties to both primary SD and CAD compared to previous generations of GI materials.