This study was undertaken to observe the carcinogenesis induced by DMBA injection to extraction wound and the efects of the tobacco-tar on that.
In order to carry out this experiment, 40 white rats were used and divided into 3 groups, two experimental(1,2) and one control group. Experimental group 1 was injected into extraction socket of lower incisor tooth with 0.1-0.2m1
DMBA in mineral oil. Experimental group 2 was injected into extraction wound of lower incisor tooth with the fixture of DMBA and 0.5gm of tobacco tar.
4 animals in each experimental group and 2 animals in control group were killed at intervals of 4th, 8th, 10th, and 12th week. At the time of death, the mandible was dissected, fixed in 10% neutral formalin, decalcified with 5% nitric acid, embedded in paraffin and sectioned 4-6 μ in thickness. The sections stained with Hematoxylin-Eosin, PAS, and Masson´s trichrome.
The results of this study were obtained as follows:
1. In DMBA injection group, extraction socket was undertaken inflammatory reaction and filled with connective tissue at 4th week, but at 8th week, fibrosarcoma initiated and dysplastic enlargement in gingiva and minor salivary glands were observable. At 10th-12th week, growth of fibrosarcoma and carcinoma was prominent
2.1n the mixture of DMBA and tobacco tar injection group, the growth of fibrosarcoma and carcinoma was initiated at 4th week and at 10th week, was prominent. Highly-differentiated squamous cell carcinoma in the gingiva and adenocystic carcinoma in the minor salivary glands were observable. At 12th week, malignancy was more prominent.
3. The growth of fibrosarcoma and carcinoma in the area of extraction wound affected the area of posterior teeth, and carcinoma in the gingiva, hyperplasia of cementum and pulp necrosis were observable.
4. The neuromatic growth in the nerve bundle and the chondromatous growth in the new bone tissue were observable.
5. Carcinogenesis induced by the mixture of DMBA and tobacco tar in the extraction wound was more prominent than DMBA alone injection and had a carcinogenic effect on the all surrounding tissue.
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