Panoramic radiographs and quantitative ultrasound of the radius and phalanx III to assess bone mineral status in postmenopausal women.

backgroundVarious mandibular indices have been developed to detect osteoporosis on panoramic radiographs. Quantitative ultrasound (QUS) is a low-cost, radiation-free method to assess bone status. The aim of this study was to compare mandibular morphometric analysis and QUS at the radius and proximal phalanx III finger.

methodsThe study involved 97 postmenopausal women, aged 48.5-71.5y (mean: 55.4). Mandibular morphometric analysis comprised: distance between upper and lower mandibular borders just behind the mental foramen (H), distance: mental foramen - inferior mandibular cortex (IM) and mandibular cortical width at the mental region (MCW). Then, ratios were calculated: MCW/IM = PMI (panoramic mandibular index), H/IM = MR (mandibular ratio). Mandibular cortical index (MCI) was used to classify the morphology of the mandibular cortex. Bone mineral status assessed using QUS at the radius and proximal phalanx III finger was compared to population mean apical bone mass (T-score). Linear regression analysis was used for correlations between continuous variables, Pearson's correlation coefficient r - for variables of normal distribution. Student's t-test was used to compare variables of normal distribution and for the latter - Mann-Whitney U-test. The level of significance was p < 0.05.

resultsMandibular height was 13.42-34.42 mm. The mean mandibular cortical width was 3.31 mm. Mean values of PMI and MR were 0.33 and 2.57, respectively. Higher mean value of Ad-SoS was found in the radius than in the III finger. Phalanx T-score values ​​were lower than those of the radius. T-score of the radius was < - 1.0 in 22 patients, indicating osteopenia. Basing on phalanx T-score, osteopenia was found in 39 patients. Category C1 of Mandibular Cortical Index was found in 48 women, C2 - in 37 women and C3 - in 12 women. Higher scores of Mandibular Cortical Index were recorded in older women. MCI significantly correlated with the skeletal status (p = 0.01) as well as with H, MCW and MR. Phalanx T-score was not correlated to PMI, MR or MCW.

conclusions1. Mandibular Cortical Index can be used as a screening tool for detecting osteoporosis. 2. Quantitative ultrasound at the phalanx III constitutes a reliable way of assessing bone status.