bracesA study of young people undergoing orthodontic treatment has advanced the dental profession’s knowledge of the impact of obesity on oral tissues.

It is now recognised that obesity represents a state of chronic subclinical inflammation mediated through the presence of excess adipose tissue. In this investigation, the consequences of obesity for orthodontic tooth movement have been investigated.

Led by Professor Martyn Cobourne and Dr Guy Carpenter at King’s College London Dental Institute, the study involved two cohorts of young people with an average age of 15 years. One group was of normal weight and the other was classified as obese based upon body mass index (BMI).

Taking samples of both saliva and gingival crevicular fluid, the researchers found that the obese young people had significantly increased inflammatory biomarkers in their periodontal tissues prior to treatment. This was associated with a significantly increased initial displacement of the teeth during the first week of treatment and a significantly increased rate of tooth movement over the alignment phase.

The British Orthodontic Society’s director of external relations, Richard George, said the research is fascinating with potential for more interesting results in the future.

‘The prevalence of obesity is on the increase in Western societies and this study provides evidence that increased BMI can have manifestations for orthodontic patients. Significantly, the patients with obesity had a pre-existing pro-inflammatory state in their periodontal tissues and this influenced how the teeth moved with fixed braces.’

Orthodontic tooth movement is mediated by an inflammatory response within the periodontal tissues following the application of orthodontic force.

Richard further commented: ‘The findings that pro-inflammatory markers in obese young people are able to influence the alignment phase of orthodontic treatment immediately prompts the suggestion of how this condition might influence other aspects of treatment.’

He explained that two known complications of orthodontic treatment are root resorption and post-treatment relapse. If obesity can affect how teeth respond to fixed braces, it might also potentially influence root resorption and long-term stability.

Professor Cobourne agreed and said that the research could deliver further interesting findings. The two groups of patients in the study are still in treatment and the research team at King’s is currently following them up to the completion of treatment.

He continued: ‘What is interesting is that we have used the same experimental model to measure and compare tooth movement in response to a variety of different clinical parameters, including self-ligating braces and the addition of vibratory forces, and we have never previously found any differences in rates of tooth movement. In this study, the presence of obesity made a significant difference.’

However, he also stated that it was important to keep these findings in context. This was a clinical study, and while rates of alignment were significantly increased in the obese group for all time-points measured, the overall time that it took to straighten the teeth, although an average of 23 days less in the obese patients, was not statistically significant. Nonetheless, this investigation demonstrates clear differences in the biochemistry of the periodontal tissues and response to tooth movement in obese subjects when compared to those of normal weight.

The study, Impact of obesity on orthodontic tooth movement in adolescents, a prospective clinical cohort study, was published in the Journal of Dental Research and can be viewed here.