The effect of vitality and dentin depth on resin tags length of resin–dentin interface in dogs’ teeth

The aim of this study was to evaluate the effect of pulpal pressure and dentin depth on the quality of hybrid layer of bonded composite. Four healthy dogs, aged between 12 and 18 months, with intact dentitions were used for the experimental work. A total of 24 teeth were available for the study by using the six upper anterior teeth of each of the four dogs used in the study. The 24 teeth included in the study were divided according to presence or absence of pulpal pressure (P) into two groups with 12 teeth in each group. P(1) teeth with positive pulpal pressure and P(2) teeth with no pulpal pressure. Each of these two groups was further divided into two subgroups, according to the cavity depth (D) they received, where in D(1) a class V cavity with depth of 1 mm was performed, while in D(2) a class V cavity with depth of 2 mm was performed. The cavities were restored with micro hybrid composite restorative material and the samples were then left in the dogs’ mouth for 30 days. At the end of the experimental period, the dogs were euthanized by injecting an overdose of thiopental sodium. The anterior part of the upper jaw was sawed out of each dog’s mouth and the teeth were sectioned to evaluate the resin–dentin interface using Environmental Scanning Electronic Microscope. Results of the study showed that the mean resin tag length value was significantly affected by vitality and dentin depth. The presence of pulpal pressure together with depth of dentin could adversely affect the quality of hybridization.