Tissue Response of Dental Pulp in Dogs following Direct Capping with Potassium Nitrate in Polycarboxylate Cement

In 6 dogs, experiments were performed to determine the tissue reaction of the dental pulp at the 7, 30 and 60 days after direct contact of the pulp with the obturation material through a microcommunication orifice with diameter up to 1 mm, formed in the fundic part of an experimental cavity. Capping of 36 mandibular premolars with traumatically exposed pulp was carried out. On the exposed pulp, polycarboxylate cement with 5% potassium nitrate was applied on 18 teeth (experimental) and a preparation containing calcium hydroxide (Calxyd) − on the opposite 18 (control) teeth. The histological preparations were observed by light microscopy and the dental pulp changes were determined by the Negm’s scale using 3 scores: weak, medium and strong inflammatory reaction. The status of the odontoblast layer was evaluated after Qvist & Qvist and the amount of reparative dentin − after Stanley. The obtained results showed that the direct capping of traumatically exposed dental pulp with potassium nitrate in polycarboxylate cement did not cause degenerative changes in the pulp-dentin complex. The histomorphological tissue response was probably due to effect of potassium nitrate and polyacrylic acid upon the regeneration in the dental pulp protected against microbial infection. It could be supposed that the good adhesion properties of the material ensured the isolation of the exposed dental pulp from the environment, creating optimal preconditions for manifestation of its natural reparative potential.