Comparison of marginal sealing ability of new generation bonding systems

The purpose of this in vitro study was to evaluate the enamel and dentine marginal sealing ability of four new generation composite bonding systems. Two Class V preparations, which were solely in enamel and dentine/cementum, were made on the buccal surfaces of 96 freshly extracted molar teeth. The teeth were randomly divided into four groups of 24 and restored with composite resin (Silux Plus) utilizing the following bonding systems: Scotchbond Multi-purpose (SB), Fuji Bond LC (FB), Prime & Bond 2.0 (PB) and Bisco One-step (BC). The restorations were finished immediately after photo-polymerization and stored in saline at 37 degrees C for 1 week. Half of the specimens in each group were then thermally stressed for 500 cycles. All restorations were then subjected to dye penetration testing, sectioned and scored. Results revealed no statistically significant difference (P < 0.05) in dye penetration scores for the different bonding systems with the exception of leakage at the dentine margins of thermally stressed specimens where FB exhibited significantly better sealing ability compared with the other bonding systems and BC exhibited significantly less leakage than PB. The marginal seal of 'one-step' (PB and BC) and resin-modified glass-ionomer (FB) bonding systems appear to be as effective as 'two step' systems like SB. Thermal stresses had some influence on marginal seal but this was both product and tissue specific.