study on the statistical index of decayed, missed and filled teeth (dmft) in secondary school students of zarand city in 2011

background: knowledge of existing situation in each region plays great role in order to prevent oral and dental diseases in people. meanwhile, dmft index is one of the best epidemiological indices in dentistry representing oral hygiene situation in society. so, this study was conducted in order to evaluate dmft index in 12- years-old students of zarand city at 2011. methods: this descriptive study was done cross – sectionally using interview, examination and questionnaire among 12- years- old students of zarand city. considering who criteria, 350 samples were selected for the study and periodontal condition, number of caries, decayed, missed and filled teeth, existing fluorosis, occlusion, orthodontic and preventive treatment were evaluated. the data were analyzed by spss software version 17. results: the mean of dmft index was 2.03 that it was zero at 121 students (34.6%) and maximum of dmft reported at 11 persons (0.6%). the 34.6% of students were caries free. results revealed no significant differences in need to orthodontic treatment between different groups of dmft. conclusion: considering who criteria, the achieved, dmft index in zarand city was not acceptable. according to the aim of who for the year of 2015 for 12 years old people (sci of less than 3dmft<1), it is necessary to perform special program for the purpose.