RESUMEN
There are relatively few systematic studies, documenting the prevalence of mucosal disorders in children and adolescents. The purpose of this study was to determine the prevalence of oral lesions in 12- to 15-year olds living in Tehran and to assess the possible relationship between the occurrence of these lesions and gender. Across-sectional study was designed in which 1020 adolescents were participated. The sample size was based upon an expected oral lesion prevalence of 25%, a precision of 0.05 and a confidence level of 99. Epi-info version 6.0 was used for statistical analysis. Two hundred eighty-six adolescents [28.0%] were diagnosed with at least one oral mucosal lesion at the time of the examination. The prevalence of any oral mucosal lesion was 29.2% among the boys and 26.9% among the girls. With the exception of melanotic macules, there were no statistically significant differences in oral mucosal lesion prevalence by gender. More than 28% of the adolescents were found to have at least one oral mucosal lesion. Melanotic macule was found to be proportionally more common in boys than girls