RESUMO
Carbamide Peroxide is routinely employed as a whitener for tooth enamel. Oral mucosa protection is recommended to avoid inflammatory reactions. Experimental work has demonstrated its irritative effect on gastric mucosa when swallowed. The activity of certain oxidizing agents as tumoral promoters has been demonstrated and associated to their capacity to induce hyperplasia. Within this context it seemed of interest to assess the possible action of carbamide peroxide as a tumoral promoter in oral mucosa with or without a precancerous condition. Its action was tested in 2 models which are highly sensitive to chemical cancerization: a) Dorsum skin or SENCAR mice treated with carbamide peroxide daily or twice a week with or without prior initiation with dimethylbenz(a)anthracene (DMBA). Control mice were submitted to the standard carcinogenesis protocol, i.e. initiation with DMBA and promotion with 12-O-tetradecanoyl phorbol acetate (TPA). b) Hamster cheek pouch submitted to topical application of carbamide peroxide 3 times a week with or without prior initiation with DMBA, hamster cheek pouch submitted to repeated topical application of DMBA as a complete carcinogen: application twice a week in the control group and identical treatment + 1 weekly application of carbamide peroxide to evaluate its capacity to enhance the process. The effects were assessed between 1 and 14 weeks of treatment at different intervals for the different experimental protocols. The control cases exhibited hyperplasia and tumor induction in keeping with the known sequence for both carcinogenesis models. None of the cases revealed a promoter or enhancer capacity of carbamide peroxide. These results indicate the lack of risk involved in the application of carbamide peroxide even in oral mucosa with a precancerous condition due to the action of initiation agents such as tobacco and alcohol.
RESUMO
The model of hamster cheek pouch carcinogenesis closely mimics the development of human oral cancer. The study of the interaction between chemical carcinogens and radiation in the process of oral carcinogenesis is of interest given that the oral cavity is frequently exposed to chemical carcinogens such as alcohol and tobacco and is the route of entry of therapeutic radiation. In this context, markers of incipient alterations associated to a process of malignant transformation would contribute to early diagnosis and follow-up. The aim of the present study was to assess the early changes produced by carcinogenic agents applied separately or combined in a two-stage carcinogenesis protocol in hamster cheek pouch. The cheek pouch of the hamsters was treated with a single dose of radiation (20 Gy) or 7,12-dimethylbenz(a)anthracene (DMBA) as initiating agents and 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoting agent for 1 or 2 weeks. The end-points chosen to identify early alterations were hyperplastic foci and silver-stained nucleolar organizer regions (Ag NOR). The data show that both markers are useful in the detection of early alterations compatible with a process of malignant transformation.
RESUMO
At present the [quot ]Impact Factor[quot ] developed by the Scientific Information Institute (Philadelphia), is an indicator of the quality of the journals in terms of the quality of the papers which are published. The results of odontological research which are presented and discussed at the annual meetings of the DAAIIO are proof of the quality and quantity of scientific production in this area in Argentina. Presentations are undoubtedly numerous. However, their diffusion and qualitative evaluation are of utmost importance. One way to estimate these parameters would be to monitor the ratio between number of presentations and their publication as full papers in journals with a system of referees (Ratio Publ./Pres.). With this aim in mind the presentations at DAAIIO over the 1980-1989 period were considered. Employing the author index of the DAAIIO meetings, we searched for possible publications in the Index Dental and the Index Medicus. The references were compared with the results presented to disregard publications which had not been previously presented at DAAIIO meetings. The data obtained were grouped according to subject area and Research Center. A total of 747 presentations led to 94 publications, the Publ./Pres. Ratio being 1/8 (12.5
). The ratio for each research center was the following: Univ. Buenos Aires 1/7; Natl. Univ. La Plata 1/8; Natl. Univ. Córdoba 1/15. The research groups with the highest publication ratios were Dent. Mat., Natl. Univ. La Plata 1/3; Clinical Pathol., Univ. Bs. As. 1/4; Oral Pathol., Univ. Bs. As. 1/4; Physiol. and Pharmacol., Univ. Bs. As. 1/4; Natl. Univ. Córdoba 1/7. The majority of the publications within 2 years of presentation were in English (69
). These results suggest that an acceptable number of presentations are published, particularly in the area of basic research. We should hope for an increase in the publication/presentation ratio in the future, particularly in the area of applied clinical research since publication would imply technical-scientific quality evaluation of the work by the experts who condition publication.