METHODS: This study analysed cross-sectional data from the Research with East London Adolescents Community Health Survey, a prospective population survey of adolescents attending state schools in East London, England. The history of NSSI was obtained using two items from the Lifestyle and Coping questionnaire (whether they have ever engaged with self-harm and the last time they engaged in such behaviours). The presence of TDIs, increased overjet and inadequate lip coverage were determined through clinical assessments by two trained dentists. Survey logistic regression was fitted to test the association of NSSI with TDIs. Odds ratios (ORs) were adjusted for socio-demographic and clinical characteristics as potential confounders.

RESULTS: The lifetime and last-year prevalence of NSSI were 11.9% and 6.7%, respectively, whereas the prevalence of TDIs was 16.5%. Neither the lifetime prevalence of NSSI (OR: 1.02, 95% confidence interval: 0.56-1.85) nor the last-year prevalence of NSSI (OR: 0.76, 95% CI: 0.36-1.61) were associated with TDIs in regression models adjusted for confounders.