Spontaneous Gingivitis Related to Hair Penetration in Rats |
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| Authors: | Aya Goto Jiro Sonoda Yuki Seki Yoshikazu Taketa Etsuko Ohta Kyoko Nakano Akira Inomata Kazuhiro Hayakawa Toyohiko Aoki Kazuo Tsukidate Satoru Hosokawa |
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| Institution: | 1.Tsukuba Drug Safety, Global Drug Safety, Biopharmaceutical Assessments Core Function Unit, Eisai Co., Ltd., 5-3-1 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan;2.Regulatory Non-clinical Japan, Global Regulatory Core Function Unit, Eisai Co., Ltd., 5-3-1 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan |
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| Abstract: | Maxillary gingivae from male and female Crl:CD(SD) rats at 12, 16, 21, and 34 weeks of
age were examined histologically. The incidence of gingivitis was approximately 40%, with
no age or sex predilection, and was most frequent between the first and second molar.
Lesions were characterized by acute focal neutrophilic infiltration into the gingival
mucosa, occasionally with inflammatory exudate. In severe cases, inflammation extended to
the periodontal ligament with abscess formation, and adjacent alveolar bone
destruction/resorption. The most characteristic finding was the presence of hair shafts
associated with the lesion, which was observed in approximately 80% of the rats with
gingivitis. These findings suggest that molar gingivitis occurs in rats from an early age
and persists thereafter, and that the main cause of gingivitis in rats is hair penetration
into the gingiva. It would be prudent to keep these background lesions in mind as
potential modifiers in toxicity studies. |
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| Keywords: | molar gingivitis hair shaft |
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