Glass polyalkenoate bond strength to dentine after chemomechanical caries removal

The bond strength of a glass polyalkenoate cement after chemomechanical 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 four groups of ten. Conventional caries removal was carried out on two groups and chemomechanical caries removal on the other two groups. Surface conditioner was applied to the dentine in one conventionally treated and one chemomechanically treated group. Glass polyalkenoate cement was applied via a metal holder to the dentine. The samples were stored 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 min-1. The mean bond strength for each group, in MPa (standard deviation), was: conventional caries removal alone 1.32 (0.51), conventional caries removal and conditioner application 2.43 (0.47), chemomechanical 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 group, coupled with the use of the conditioning agent, were significantly greater than for the conventionally treated groups alone at the 0.05 level. There was no significant difference between the chemomechanically treated groups or the group conventionally treated with conditioner application. SEM examination revealed a combination of cohesive and adhesive bond failure. Different morphologies between the conventionally and chemomechanically treated surfaces were also evident.