Bonding of crown and bridge adhesive resins to dentine

The shear bond strength of three adhesives, Panavia 21, Superbond, All Bond C&B Cement, and Variolink (a dual cure resin) to various dentine depths were determined. Fifteen human fully erupted permanent first and second molars were wet ground using 500 and then 800 grit abrasive papers to expose the superficial, middle and the deep dentine, for each adhesive tested. Five samples were prepared for each dentine depth. The adhesives were bonded to the samples using gelatine capsules and were matured for 24 h in water at 37 degrees C. The samples were debonded in shear using tensile testing machine at a cross-head speed of 1 mm/min. The data were analysed using ANOVA and the Tukey test. The fracture surfaces were examined by optical microscopy. The bond strength of Superbond to dentine was significantly higher (P<0.05) than any of the materials tested. The bond strength of all materials tested was shown to be affected by dentine depth, except for Superbond. Fractured dentine specimens showed that the samples of Superbond are almost cohesive (>90%), and the samples of other adhesives are mostly adhesive (>70%). These results confirm that Superbond is capable of forming a bond at various dentine depths.