Experimental Study On Odontogenic Tumor Derived From Epithelial Rests Of Malassez Induced By Local Administration Of N-Methylnitrosourea(MNU)

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The objective of this study was to examine the possibility that epithelial rests of Malassez can give origin to odontogenic tumours. A mixture of N-methylnitrosourea (MNU) and alginate impression material for dental use was injected on the periostium of buccal side of the left mandibles of 5-week-old Wistar male rats(300mg/kg). The mixture remained at treatment-site for several months. The rats were killed 1, 3, 5, and 8 months after the injection. After 5 and 8 months, the epithelial rests of Malassez at the cervical and bifurcational portions of the first, second, and third left mandibular molars were significantly enlarged in size and the alveolar bone around the lesion was resorbed by multinucleated cells in all rats. The epithelial masses were characterized by enamel organ-like structure, deposition of eosinophilic amorphous material, duct-like structure, and squamous metaplasia. In addition to these masses in molar regions, odontogenic tumours in incisal regions and carcinomas and sarcomas in buccal region, knee, bladder, and skin were induced. Local administration of a mixture of MNU and alginate impression material for dental use can induce odontogenic tumours from the epithelial rests of Malassez in high incidence.