Dental pulp infarction in female rats following inhalation exposure to 2-butoxyethanol

Female Fischer 344 (F344)/N rats (10 per exposure group) were exposed to 2-butoxyethanol (BE) vapors (0, 31, 62.5, 125, 250, or 500 ppm 6 h/d, 5 d/wk, for 13 weeks) to characterize its prechronic toxicity. Dental lesions consisting of bilateral multifocal dental pulp thrombosis, pulp infarction, and odontoblast infarction were noted in the maxillary incisors of 3 of 4 rats from the 500-ppm group that were sacrificed when moribund during the first week of exposure. In addition, 1 rat from the 500-ppm group that was sacrificed on day 32 had similar unilateral incisor lesions but with additional findings consistent with a unilateral maxillary incisor fracture. In contrast, rats sacrificed after 13 weeks of exposure lacked dental lesions. In conclusion, BE has the potential to cause pulp thrombosis and odontoblast infarction in female rats. The apparent variability in response to BE noted in moribund sacrificed vs terminally sacrificed rats was attributed to development of tolerance to BE-induced hemolysis and subsequent incisor regeneration.