The influence of orthodontic treatment on dental caries: An Australian cohort study

To assess the influence of orthodontic treatment on long-term caries experience in 30-year-old South Australians. The research hypothesis that was tested was that those with previous orthodontic treatment would have lower caries experience.

In 2005-2006, a sample of 1859 30-year-olds from Adelaide, South Australia, who comprised 47% of participants who had previously taken part in an oral epidemiology study in 1988-1989, were traced from the Australian electoral roll and invited to participate in a cross-sectional study investigating long-term dental health outcomes. Participants completed a questionnaire that collected information on socio-demographic characteristics, dental health behaviours and receipt of orthodontic treatment. This was followed by clinical examination. The outcome variables were the summed decayed, missing and filled teeth (DMFT) score, and its individual components. Data were analysed using negative binomial regression.

The response rate for the questionnaire was 34% (n = 632). There were no systematic differences between those who were followed up and those who were not followed up. Clinical data for 448 participants were available for analyses, representing 24% of the originally contacted individuals. By the age of 30, over a third of participants had received orthodontic treatment. Regardless of initial malocclusion classification, orthodontically treated participants had a lower DMFT score at age 30 but this did not reach statistical significance. Adjusted models controlling for socio-demographic, dental health behaviour and malocclusion status showed no associations between orthodontic treatment and decayed (Exp B: 1.00, 95% CI: 0.72-1.40), missing (Exp B: 1.00, 95% CI: 0.59-1.69), or filled teeth (Exp B: 1.18, 95% CI: 0.93-1.51) or overall DMFT (Exp B: 1.12, 95% CI: 0.88-1.41).

There was no difference in the long-term caries experience of South Australians aged 30 years based on past orthodontic treatment. Our study does not support the contention that those treated orthodontically have better dental health later in life.