title: Hexachlorobenzene-induced incisor degeneration in Sprague-Dawley rats.
abstract: Hexachlorobenzene (HCB) was administered to female Sprague-Dawley rats in a 13-week toxicity study conducted for the National Toxicology Program (NTP). Groups of 10 rats were treated by gavage with 0.0, 0.03, 0.1, 0.3, 1.0, 3.0, 10, or 25 mg/kg HCB in corn oil 5 days/week for 13 weeks. Dose-dependent, region-specific, maxillary incisor degeneration was observed in animals given HCB at doses of 1.0 mg/kg/day and higher. Treatment with 1.0 mg/kg/day resulted in focal mesenchymal cell vacuolation and focal osteodentin formation within the pulp. Lesions were restricted to a short linear region subjacent to the odontoblast layer along the lateral aspect of the incisor at the level of the dentin-enamel interface. When observed in both incisors, lesions were bilaterally symmetric. Treatment with 3.0 mg/kg/day resulted in lateral and medial pulp lesions and focal odontoblast degeneration with dentin niche formation along the lateral incisor margin in some animals. Treatment with 10 mg/kg/day resulted in a higher incidence of lateral dentin niches and a low incidence of medial dentin niches. In animals treated with 25 mg/kg/day, a high incidence of bilaterally symmetric, lateral and medial, dentin niches were observed. The morphology and distribution of HCB-induced incisor lesions in rats are consistent with injury to a selective population of preodontoblasts.
authors.affiliation: Pathology Associates, A Division of Charles River Laboratories, Inc, West Chester, Ohio 45069, USA. plong2@cinci.rr.com
authors.forename: Philip H
authors.initials: PH
authors.lastname: Long
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Herbert
authors.forename: Abraham
authors.initials: A
authors.lastname: Nyska
mesh_terms: D000284:Administration, Oral; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005659:Fungicides, Industrial / Q000008:administration & dosage / Q000633:toxicity*; D006581:Hexachlorobenzene / Q000008:administration & dosage / Q000633:toxicity*; D007180:Incisor / Q000187:drug effects* / Q000473:pathology; D008437:Maxilla; D051381:Rats; D017207:Rats, Sprague-Dawley; D014076:Tooth Diseases / Q000139:chemically induced* / Q000473:pathology
chemical_list: D005659:Fungicides, Industrial; D006581:Hexachlorobenzene