Objective: To investigate the association between orthodontic treatment need (OTN) and caries experience (CE).
Subjects and methods: Using a stratified sampling method, 748 subjects (355 females, 393 males; mean ± standard deviation age 15.11 ± 2.23 years) were examined. The Dental Aesthetic Index (DAI), DMFT, simple (DMFT > 0) and severe CE (DMFT > 8) were recorded. Socio-economic status (SES) was assessed by recording parental education, mother's employment status, and household size.
Results: Higher (but not statistically significant) CE was observed in subjects with OTN (DAI > 30). The association between DAI and DMFT scores was not significant (rho = 0.05). Mean DMFT score did not vary significantly between the SES and OTN subgroups. In children with a household size >6 persons (n = 85), OTN was associated with higher CE and a higher prevalence of severe CE compared with those without OTN. In this group, when DAI treatment need grade increased, severe CE prevalence also increased from 10.8% to 50%. Similarly, in those with OTN and household size >6 persons, the odds of observing subjects with severe CE was 4.6 times higher (95% confidence interval 1.45-14.55) compared to those without OTN.
Conclusions: Associations were observed between OTN and CE and also between the prevalence of severe CE and the severity of malocclusion in children with a household size >6 persons. The current findings suggest that the relationship between caries experience and malocclusion should be assessed in a wider context of SES and background factors.