Methods: 631 student of 8-12 years old randomly selected from the student s of East of Tehran city school. Examinations for dental caries were carried out according to the World Health Organization criteria and methods. The DMFT/dmft index and its components were determined and record along with demographic data. The effect of different demographic factor and oral hygiene habit on DMFT/dmft index was examined by means of linear regression
Results: The results showed that DMFT score of the students was 1.32±1.6 and their dmft score was 2.82±2.75. The mean DT component of DMFT was 0.94 and the mean dt part of dmft index was also 1.83. 42.9 % of the participants need dental treatment in their permanent teeth while 56.1% of them required treatments in their deciduous teeth. Gender, birth order, mother education level, refer to dentist, dental floss usage and frequency of fluoride mouthrinse showed significant influences on the DMFT index (p<0.001, p<0.004, p<0.019, p<0.022, p<0.044, p<0.001). Gender, fluoride mouthrinse use and duration of mouthrinse usage was significant on the dmft index(p<0.0001, p<0.014, p<0.0001).
Conclusions: untreated caries experiences, especially in the deciduous teeth, were high in the 8-12 years old students, and about half of the samples required dental treatments for their permanent or deciduous teeth