Histologic study of pulp capping using chlorhexidine in dogs.

This histological study was conducted to compare the pulp reactions to chlorhexidine and calcium hydroxide. Twenty permanent premolar teeth of beagle dogs were mechanically exposed under aseptic conditions. The pulp was then capped with one of the following: chlorhexidine 0.2% on the left side and calcium hydroxide (dycal) on the right side of the same dog. Maxillary second premolars were extracted from each dog three weeks after the pulp capping procedure. Maxillary third premolars and mandibular first premolars were extracted at 6 weeks and 9 weeks respectively. The mandibular second premolars were extracted three months after the pulp capping procedure. The specimens were fixed in 10% formalin and decalcified in 5% formic acid. Serial sections, 7 microns thick, were prepared and stained with hematoxylin and eosin. Teeth treated with chlorhexidine or with calcium hydroxide were well tolerated by the dental pulp at 3 and 6-week intervals. Pulps treated showed satisfactory pulp reaction and the odontoblastic layer appeared to be normal and in its configuration. Inflammatory response was not present at the 6-week time interval. At nine weeks, the inflammatory response was severe in those teeth treated with calcium hydroxide. There were no remarkable histological differences among the treatment groups at 12 and 15 weeks. These specimens showed complete loss of pulpal architecture. Regressive changes were seen and microscopic specimens revealed presence of spaces and intertwining bundles of films in the pulp.