A comparative study of three treatment methods of direct pulp capping in canine teeth of cats: a histologic evaluation

Direct pulp capping (DPC) is coverage of exposed pulp by a biocompatible material after traumatic or carious exposure. The purpose of this procedure is to seal this spot against bacterial leakage, stimulate dentinal barrier formation, and maintain the vitality of the pulp. Several factors contribute to the consequence of this treatment, such as the kind of material used and the procedural technique. The aim of this study was to evaluate histologically the outcome of DPC using three methods. Thirty-six canine teeth of nine cats were selected for this experiment. After the cats had been anesthetized, the teeth were exposed under sterile condition. The teeth were randomly divided into three groups. In group I, the exposed pulp was covered with mineral trioxide aggregate (MTA) alone. In group II, the pulp, after being treated with erbium:yttrium–aluminum–garnet (Er:YAG) laser (energy = 200 mJ, pulse duration = 700 μs, repetition rate = 3 Hz, exposure time = 15 s, no air, no water, beam diameter = 0.6 mm), was covered with MTA. In group III, the pulp was treated with laser and covered with calcium hydroxide [Ca(OH)₂]. All cavities were filled with amalgam after DPC. After 4 months, the animals were sacrificed and block sections were prepared. The specimens were histologically evaluated. The data were analyzed by Mann–Whitney and chi-square tests. Dentinal barrier had formed in all groups. The laser + MTA group showed little superiority to the other groups in dentinal barrier formation, type and intensity of inflammatory responses, and soft tissue changes, especially necrosis, but these differences were not statistically significant (P > 0.05). We concluded that laser + MTA produced better healing. According to the conditions in this study, Er:YAG laser could be used in direct pulp capping treatment in combination with both common materials.