Detecting young Japanese adults with undetected low skeletal bone density using panoramic radiographs

The cortical width below the mental foramen of the mandible determined from panoramic radiographs is a useful screening tool for identifying elderly individuals with a low skeletal bone mineral density (BMD). However, whether the mandible cortical width (MCW) is useful for identifying a low skeletal BMD in men and women of 40 years or younger is not known. The BMD of the calcaneus was measured by ultrasonography bone densitometry in 158 men and 76 women aged 18-36 years. A logistic regression analysis adjusted for age was used to calculate the odds ratios and 95% confidence interval (CI) of having a low calcaneal BMD, according to the quartiles of the MCW. The areas under the receiver operator characteristic curve (AUC) for identifying participants with a low calcaneal BMD using the MCW were assessed to evaluate the diagnostic efficacy of the MCW. In men, the adjusted odds ratios of a low calcaneal BMD associated with the second, third and lowest quartiles of MCW were 5.66 (95% CI, 0.61-52.23), 5.43 (95% CI, 0.59-50.18) and 33.22 (95% CI, 3.97-276.94), respectively, compared with the highest quartile, while no significant trend in the adjusted odds ratios was observed in women. The AUC for identifying participants with a low calcaneal BMD based on the MCW was 0.796 (95% CI, 0.702-0.890) in men and 0.593 (95% CI, 0.398-0.788) in women. MCW determined from panoramic radiographs can be used to identify undetected low calcaneus BMD in young adult men, but not in young adult women.