RESUMO
Leukoplakia is the most common premalignant or potentially malignant lesion of the oral mucosa and its potentiality for malignant transformation is unpredictable. The aim of the present study was to evaluate p53 expression in normal oral epithelium, leukoplakia and oral squamous cell carcinoma. The standard Biotin streptavaidin peroxidase immunohistochemical staining method was used to study the expression of p53 on formalin fixed, paraffin embedded blocks of 8 cases of squamous cell carcinoma, 20 cases of leukoplakia and 10 cases of normal oral epithelium. There was no significant difference between immunostaining of leukoplakia and normal epithelium groups in the expression of P53, but the distribution patterns of p53 was mainly localized in the basal layer in the group of normal oral mucosa, while it extended into the suprabasal cell layer in leukoplakia group. P53 expression in squamous cell carcinoma group was higher than other groups. Considering the findings the expression of p53 in suprabasal cell layers in leukoplakia might show poor clinical outcome and alterations of p53 might be an important factor in the development of oral cancer