Variation in time of emergence of permanent teeth among urban and rural Jordanian school children.

OBJECTIVE: To investigate the variation in time of permanent tooth emergence between urban and rural Jordanian school children. METHODS: In this observational cross-sectional study, 1900 pupils at urban schools, and 772 at rural schools aged 5-16 years in both genders were examined for emergence of permanent teeth at different urban and rural primary schools and kindergartens in Jordan between March and June 2010. Probit analysis was used to estimate the median age of emergence per permanent tooth. RESULTS: The emergence ages for most of the permanent teeth were generally advanced in urban schoolboys in contrast to their fellows at rural schools. However, the differences were only statistically significant for the maxillary canine and maxillary premolars. Compared with boys, schoolgirls had smaller variation in permanent tooth emergence across school region, and none of the differences were statistically significant. CONCLUSION: Urban schoolboys have accelerated emergence of the maxillary canine and maxillary premolars compared to rural boys. The potential etiology behind this finding needs to be investigated further in the future.