A Eskandarizadeh - Assistant professor
M.A Naderi nejhad

Caries ferr is  an epidemiologic index for prevalence of dental caries in a society and it means that persons who do not have any dental caries,in other words,that equal to DMF=۰.to determine the prevalence of caries ferr in ۱۲ year-old student in Guidance school in sirjan city,this study was carried out with the method of WHO index in ۱۹۹۶.on the bases of a pilot study the of sample size was determined to be ۳۰۰ persons(۱۵۰ girls and ۱۵۰ boys).this sample was selected by stratified cluster sampling.after dental examination and filling the WHO forms,the obtained data were statistically analyzed and the results were as follows.۳۴.۷ percent of ۱۲ year-old(boy and girl) adolsent were caries ferr.۳۹.۳ percent of boys and ۳۰ percent of girls in this study were caries free.according to WHO index caries prevalence was ۶۵.۳% in ۱۲-year-old adolesents in sirjan which is considered relatively low.

Dental Caries, caries free, sirjan city