Histopathological Evaluation of Pulp Reaction to Potassium Nitrate in Polycarboxylate Cement Compared with Mineral Trioxide Aggregate in Immature Dogs' Teeth

Abstract

Objective The vitality of the pulp and the formation of new dentin are important for the success of direct pulp capping (DPC). Accordingly, the present study aims to histologically evaluate the pulp reaction to potassium nitrate in polycarboxylate cement (KNO3/PCA) compared with mineral trioxide aggregate (MTA) in immature dogs' teeth. DPC was done on 48 teeth in three dogs (16 for each dog, 8 for each material). Materials and Methods After 2, 3, and 4 months, a dog was euthanized at each time interval. Capped teeth were extracted, demineralized, and processed for histopathological examination based on the presence of inflammation, granulation tissue, hard tissue, and dentin bridge. Results Inflammatory changes were absent in both MTA- and KNO3/PCA-capped teeth at the three time intervals. The incidence of granulation tissue formation was higher in MTA- (75, 87.5, and 87.5%) than in KNO3/PCA-capped teeth (62.5, 75, and 75%) after 2, 3, and 4 months after DPC, respectively. Hard tissue was seen after 3 months of DPC with both MTA and KNO3/PCA. It was more evident in MTA-capped teeth with an incidence of 75 and 75%, and 12.5 and 25% in teeth capped with KNO3/PCA after 3 and 4 months, respectively. Dentin bridge was only noticed in MTA-capped teeth after 3 and 4 months intervals. Conclusion Taken all together, pulpal responses in the form of granulation and hard tissues, and dentin bridge formation are more evident in MTA-capped teeth than those capped with KNO3/PCA in immature dogs.