The purpose of this study was to observation the pathogenesis and carcinogenesis of lining epithelium of odontogenic keratocyst which injected with DMBA ( 9,10-dimethyl-1,2 -benzanthracene, Sigma Chemical Co.) after ;;nplantation of upper gingival epithelium of rats.
Bony cavity was formed in the left mandibular body area of Sixty Sprague-Dawley rats with #3 round bur and then gingival epithelium was implanted to be inner surface. Six experimental animals of group 1 were sacrified at 12,3,4,6 weeks after implantation respectively. Thirty experimental animals of group 2 were injected with DMBA around the bony cavity at 6 weeks after implantation and then six experimental animals of group 2 were sacrified at 2,4,6,8,10 weeks after injection with DMBA respectively.
And the formalin-fixed paraffin embedded sections were stained as H-E staining routinely, PAS staining for glycogen, and Ayoub-Shklar staining for keratinization, and then observed with light microscope.
The obtained results were as follows
1. In group 1, gingival implantation-induced cyst-like lesion was composed of thin lining epithelium and connective tissue wall at 4 weeks, and formed odontogenic keratocyst at 6 weeks.
2. In group 2, odontogenic keratocyst revealed inflammatory response by DMBA injection at-2 weeks, basilar hyperplasia of lining epithelium at 4-6 weeks, and carcinoma in situ at 8 weeks. After all odontogenic keratocyst proceeded to odontogenic carcinoma showing highly or well differentiated squamous cell carcinoma at 10 weeks.
3. The lining epithelium of odontogenic keratocyst was infiltrative growth and the cystic wall accompanied with fibrosarcoma and rhabdomyosarcoma at 8 weeks in group 2.
4. The epithelial island inferred as ameloblastomatous changes were found around the tooth germ of incisor teeth, and did adenoma-like changes in minor salivary gland and hypercementosis in molar teeth.
5. In PAS reaction, prickle cell layer and cystic wall revealed strong reactivity, and weak or negative reactivity toward poorly differentiated cells. In Ayoub-Shklar reaction, strong reactivity was revealed in prickle cell layer of lining epithelium and area of dysplastic proliferation.
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