Effects of a bleaching agent containing 35% carbamide peroxide on the immunolocalization of cyclin D and p16

The evidences that p16 and cyclin D alterations occur in the earlier stages of many human cancers and that its immunolocalization can be used to study the cell cycle regulation, coupled with the possibility that chronic use of carbamide peroxide would induce DNA damage and cell cycle alteration, prompted us to analyse the effect of carbamide peroxide on the immunolocalization of these proteins in rat oral mucosa. Ten male Wistar rats were selected and submitted to topical application of 35% carbamide peroxide over buccal mucosa. The procedures were carried out twice a week for 3 months consecutively. The animals were killed after the last treatment and the buccal mucosa was removed and stored at -70 degrees C. Only distilled water was applied over the buccal mucosa of the control animals. The biotin-streptavidin amplified system was used for identification of cyclin D and p16 antigens and the percentage of basal and suprabasal cells positive for each one were obtained. The results did not show any difference between the experimental and control groups regarding the immunolocalization of cyclin D and p16. In conclusion, the present study showed that chronic use of carbamide peroxide does not induce cell cycle alteration in the oral mucosa of rats.