The Journal of

  Background: The first permanent molar is the biggest permanent tooth having the most important role in chewing, preservation of vertical height of the jaws and esthetics. On the other hand, because of it's special anatomic form, early eruption, lack of mother’s awareness about it’s eruption and misidentifying it from primary teeth, this tooth is very susceptible to caries. Its caries is an indicator for predicting caries susceptibility in the other teeth.

  The aim of this study was to indicate the prevalence of DMFT in first permanent molar among primary school children in Yazd.

  Methods: In this study, students of totally 6 public and private schools were selected randomly and first the molar tooth of 15 students from each level was examined and DMFT was recorded. Data were then analyzed by SPSS software, ANOVA and t-Test.

  Results: The least DMFT was identified in 7-year-old students (0.36 ± 0.92) and the highest rate was seen in 11-year-students (1.17 ± 1.26). There was a significant relationship between DMFT and age (P< 0.0001).

  - Among D,M and F, maximum mean was related to F or filled teeth and minimum was related to M or extracted teeth.

  - DMFT in girls (1.15 ± 1.33) was higher than boys (0.51% ± 0.88) (P<0.0001).

 - DMFT among students with lower economical status was significantly higher than those with better economical condition.

 Conclusion:Increasing DMFT of first permanent molar during 3-4 years after eruption demands attention to early oral education, prevention and treatment of it.