GLASS POLYALKENOATE BOND STRENGTH TO DENTIN AFTER CHEMOMECHANICAL CARIES REMOVAL

The bond strength of a glass polyalkenoate cement after chemomechanica l caries removal of dentine with or without the use of a conditioning agent and the mode of bond failure using scanning electron microscopy was examined. Forty extracted carious human teeth were divided into fo ur groups of ten. Conventional caries removal was carried out on two g roups and chemomechanical caries removal on the other two groups. Surf ace conditioner was applied to the dentine in one conventionally treat ed and one chemomechanically treated group. Glass polyalkenoate cement was applied via a metal holder to the dentine. The samples were store d for 7 days in a moist environment at 37 degrees C. The samples were subjected to a shearing-type stress at a cross-head speed of 0.5 mm mi n(-1). The mean bond strength for each group, in MPa (standard deviati on), was: conventional caries removal alone 1.32 (0.51), conventional caries removal and conditioner application 2.43 (0.47), chemomechanica l caries removal alone 2.47 (0.99) and chemomechanical caries removal and conditioner application 2.76 (0.96). Mean bond strengths for both the chemomechanically treated groups and the conventionally treated gr oup, coupled with the use of the conditioning agent, were significantl y greater than for the conventionally treated groups alone at the 0.05 level. There was no significant difference between the chemomechanica lly treated groups or the group conventionally treated with conditione r application. SEM examination revealed a combination of cohesive and adhesive bond failure. Different morphologies between the conventional ly and chemomechanically treated surfaces were also evident.