Neural Changes in Periapical Lesions after Systemic Steroids in the Ferret

Abstract

This study was intended to clarify the relationship between the neural changes which occur around the apex of the ferret canine after pulpectomy and the inflammatory process induced by the procedure. In 12 young adult ferrets, under general anesthesia, the pulps in the mandibular canine teeth were removed and replaced with gutta percha and Grossman's sealer. Six of the animals were treated with dexamethasone to reduce the inflammatory response. Three months later, the animals, again under general anesthesia, were perfused with a fixative mixture. Three unoperated animals that had not been treated with dexamethasone were also perfused. The mandibular canine teeth and their supporting tissues were removed, processed, and serially sectioned. Three-dimensional reconstructions of the periapical lesions in each animal were assembled and their volumes measured. The density of innervation in the periapical region was estimated. The mean lesion volume in the pulpectomized animals not treated with dexamethasone was 3.54 (± 2.27) mm³ and in the dexamethasone-treated animals 1.33 (± 1.31) mm ³. The differences were statistically significant when tested by the Mann-Whitney U test (p < 0.01). Bacteria were not seen within any of the lesions. The innervation density beneath the canines in the pulpectomized animals not treated with dexamethasone was 164 units per mm² (± 80) and in the steroid-treated animals 151±68 units per mm². In the control, untreated animals, the innervation density was 22 ± 10 units per mm².The difference between the steroid-treated pulpectomized animals and the untreated pulpectomized animals was not statistically significant (p > 0.5). The difference between both pulpectomized groups and the unoperated controls was significant (p < 0.01). Neural proliferation beneath pulpectomized teeth was not related to the size of the inflammatory lesion.