ABSTRACT
Leukoplakia, is considered as the most common precancerous oral lesion. Numerous researches have shown that the effect of various risk factors in malignancy of leukoplakia differs in different societies. Being so, this study was desighned to evaluate the probability rate of malignant transformation of oral leukoplakic lesions in relation to risk factors of age, sex, smoking habit of patients, clinical appearance and site of the oral lesions in Shiraz from 1368 to 1388. This retrospective analytical-descriptive research was performed by collecting all leukoplakia from the Shiraz Nemazi and Khalili Hospitals as well as Oral Medicine and Oral Pathology Departments of Shiraz Dental School from 1368 to 1388 were selected according to their files. Patients with malignant transformation considered as the target group and those without such transformation named control group. Risk factors such as age, sex, smoking habit, clinical appearance and site of the lesions, as independent factors were evaluated in relation to their effect in malignant transformation of the oral leukoplakia through recording of necessary data via filling of special questionnaires. Chance rate in both groups was also evaluated. Data were analyzed by Excell, SPSS and Epi statistical software. Malignant transformation rate of oral leukoplakia was 40.8%. This rate showed increase with age increase specially after, forty years. The malignancy rate in females after the age of forty was higher than males. Although smoking will increase the chance of oral leukoplakia, most malignant transformations, were seen in non-smokers. Tongue was the most site and lips were the least common site for malignant transformation and white and red lesions [erythroplakic lesions] have the highest rate of malignant transformation in both sexes. Data, showed that factors such as age, sex, smoking habit, clinical appearance and site of oral lesions were in direct relation to malignant transformation of oral lesions of leukoplakia