A population survey of early factors associated with permanent tooth emergence: findings from a prospective cohort study.

OBJECTIVES

Studies investigating influencing factors of permanent tooth eruption/emergence have primarily focused on anthropometric measurements while less attention has been paid to the effect of perinatal factors. We aimed to explore early factors associated with eruption status of permanent teeth among 12-year-olds through a population-representative prospective cohort.

METHODS

A community sample of Hong Kong children born in 1997 was obtained by random sampling from local secondary schools. Participants' background information including birth characteristics, prenatal and early childhood exposures, family socioeconomic status and medical records was prospectively collected. Clinical examination of tooth emergence was conducted in 2010. Children were divided into complete emergence (of 28 permanent teeth) and partial emergence groups based on clinical examinations. Bivariate analyses were used to assess the association of tooth emergence status with each putative predictor. Unadjusted and adjusted logistic regression models were applied to select the best predictors for tooth emergence status at age 12.

RESULTS

Complete background information and clinical data were available from 514 children (76.9% of the invited participants). Bivariate analyses showed that the average birthweight in the partial emergence group was significantly lower than the complete emergence group (mean difference 0.2 kg, P = 0.006). The finding was confirmed by logistic regression analyses. In the adjusted regression model, it was found that for every 1 kilogram increase in birthweight, the odds of having partial emergence would be lowered by 0.49 (odds ratio 0.49, P = 0.006).

CONCLUSIONS

Birthweight is associated with status of permanent tooth emergence at 12 years of age, as observed from a population-representative sample of Hong Kong children.