The evaluation of prevalence of carabelli cusp in maxillary permanent first and relating factors in student of faculty of dentistry of Islamic Azad University in semester 2005-2006

in anthropology, one way to find the relations between communities and races, is evaluation of prevalence rate of the structural and genetic traits in each communities and races. The goal of this study was to determine the prevalence rate of carabelli trait in the maxillary first molar and it’s relation in the dental branch of Islamic Azad University as a source of in formations in the anthropological study. this discriptive study was carried out on the study cast of 360 sample (180 mal, 180 female) based on random sampling for each person we prepared a data sheet and at last we evalvated the prevalence rate of this trait with this data. Result with respect to the relative factors (sex) was evaluated. The result was classified in two main group of present and absence and four subgroup of unilateral, bilateral, developed, non developed. Data were analyzed using chi-square. 66.9% of evaluated group have carabelli trait and 33.1% of them haven’t this trait and from the group which have the carabelli trait 77.2% are bilateral, 22.8% are unilateral 116 sample of 180 male sample and 125 sample of 180 female sample have carabelli trait which according to Chi-square and PValue test are more than 0.05 and in 241 sample which have carabelli trait, 101 sample (49.9%) have develop form of this trait in the form of cusp. Present of this trait in the Iranian community are noticeable which was usually bilateral a have no specific relation with sex.