PERIODONTAL INFLAMMATORY AND CYST-LIKE LESIONS IN BDF1 AND B6C3F(1) MICE

Periodontal inflammatory and cystlike lesions were detected in aged BD F1 and B6C3F(1) mice. Lesions were unilateral, single, and located in the labial region of the incisor teeth. The largest cystlike lesion de formed the skull. Histologically, the cystlike lesions were classified into three types: predominantly an inflammatory reaction, predominant ly a cyst formation, and a mixed lesion. These periodontal inflammator y and cystlike lesions were pathogenetically similar and were consider ed sequential changes; the lesions showing both cyst formation and inf lammatory reaction seemed to be intermediate along a path toward forma tion of large cysts. The cysts probably were derived from periodontal tissue and developed as a result of inflammatory reaction to foreign b odies, including hair. The term ''murine periodontal cyst'' is propose d for this lesion. Detailed pathogenetic studies on murine odontogenic cystic lesions may be warranted.