Method: A sample of 715 children (mean age 6.7 years) from 6 different elementary schools (3 of them represented urban areas and another 3 represented rural areas) was examined at baseline. 660 Children had taken the follow-up examinations 24 months later. Eruption and caries experience were recorded using the WHO criteria. Chi-square tests were performed to detect the differences between genders and between rural/urban populations
Result:
The eruption rate of the first permanent molars is 75.5%. There were no significant differences (p=0.16) between urban areas (73.2%) and rural areas (77.8%) but there were significant differences (p=0.02<0.05) between girls (79.2%) and boys (71.7%).
5.6% of the population had caries in their first molars at baseline, 7.6% of girls with 3.6% of boys, and caries prevalence in rural areas (7.5%) was higher than in urban areas (3.8%). These trends related to gender and social economic condition kept developing: after 24 months, caries prevalence of 1st molar was totally 24.4%, with significant differences between genders (girls: 28.7%, boys: 20.2%) and areas (rural: 37.3%, urban: 13.3%).
Conclusion: Quiet a few children below 6 years have erupted 1st molars. For their poor ability of self oral health care and unhealthy eating habit, these teeth are at very high level of caries risk. Appropriate prevention, such as fissure sealant, should be taken soon after tooth eruption.