Difference Of The Bonding Strength Of Three Adhesive Resin Luting Systems After Water Storage

ObjectiveThe purpose of this study was to evaluate the influence of water storage on bonding strength of redicular dentin using three resin luting sysytems and the failure modes after push-out test, and to observe the difference of bonding strength at different root regions.MethodsSixty extracted sound maxillary central incisors were endodontically treated and cut transversely 2 mm coronal to the cemento-enamel junction. After post space preparation, the teeth were assigned to three groups with 20 teeth each. The post space of all samples in three groups were filled with Super Bond B&C (GroupⅠ), Panavia F (GroupⅡ) and 3M ESPE RelyX Unicem (GroupⅢ) respectively. The teeth of each group were then divided into two subgroups with 10 teeth each. Then they were stored in deionized water. After one week, the teeth of one subgroup in each group were serially sectioned into 6 slices of 1mm-thick, and the slices were push-out tested employing a universal testing machine, at 0.5 mm/min cross-head speed. The left subgroups were push-out tested after 6m water storage. The bond strength of coronal, middle and apical thirds was measured and recorded separately. After push-out test, the failure mode of each sample was assessed using a microscope at 50×magnification. SPSS 16.0 were used for statistical analyses. ResultWater storage for 6 months have significantly different effects on bond strength to root canal dentin (P<0.05).Bonding strength for crown thirds was higher than that for apiacl thirds all of three different luting cement systems (P<0.05). And there were significant differences among three adhesive systems on bond effectiveness. In each group, adhesive failure mode and the mixed failure mode are the predominant failure mode. Cohesive failures within dentin and within the resin cement occurred only rarely.ConclusionWater storage could reduce bond strength to root canal dentin. Total-etching adhesive system was recommended.