A study of graduate orthodontic students at the university and a practising orthodontist--who'd been working for 18 years--showed that long hours of bending low and working in patients' mouths put heavy strain on the lower back and neck--burdens that translated into weights of up to 138 kilograms in males and 93 kg in females. The total duration of daily work would amount to an hour's continuous load on the spine of 450 kg for men and 275 kg for women.
Results of the study appear in the February issue of Clinical Biomechanics. The subjects, aged 27 to 36, (the practicing professional was 48) were videotaped performing their regular duties and the recorded postures were analysed frame by frame for top to bottom compression load, side to side shearing load and exposure time.
"Musculoskeletal disorders of the back and neck among orthodontists, and likely other similar professions are prevalent, but because they don't necessarily do heavy lifting or tasks that put an instant load on the back, these disorders have not been investigated," said Dr. Shrawan Kumar, a professor of physical therapy at the University of Alberta.
"Although the tasks appear to be light and harmless, by virtue of the frequency and duration of their performance, they are rendered hazardous."
In reviewing the records of private clinics, the study showed that orthodontists treat an average 70 patients per day with the help of up to five assistants. The body stress was induced by long periods of sitting (about 70 per cent of their workday), with 90 per cent of the strain coming from the tasks of applying, removing or adjusting braces.