Panoramic-based mandibular indices in relation to mandibular bone mineral density and skeletal status assessed by dual energy X-ray absorptiometry and quantitative ultrasound

Objectives: The panoramic-based indices (Mandibular Cortical Index-MCI, the height of mandibular inferior cortex-IC (mm), Panoramic Mandibular Index-PMI, Mandibular Ratio-MR) were used to evaluate their diagnostic efficacy and to determine whether they correlate with bone mineral density (BMD (g/cm(2))) of the mandible and hip, and with ultrasound parameters of the calcaneus and hand phalanges in postmenopausal, edentulous women. Methods: Basing on MCI women were divided into three subgroups differed in the appearance of the mandibular cortex (C1 n = 6, C2 n = 16, C3 n = 8). BMD of the hip (neck-BMD, Ward's-BMD, trochanteric BMD) and mandible (m-BMD) were measured by dual-energy X-ray absorptiometry (DXA). Calcaneus using Achilles (Speed of Sound-SOS (m/s), Broadband Ultrasound Attenuation-BUA [dB/MHz], Stiffness Index-SI [%]) and hand phalanges (amplitude dependent speed of sound-Ad-SoS (m/s)) using DBM Sonic 1200 were assessed by Quantitative Ultrasound (QUS). Results: There were no significant differences between subgroups in parameters measured except for significant differences in m-BMD (P<0.01). Only m-BMD correlated significantly with DXA (r = 0.43 - 0.45, P < 0.05) and QUS (r = 0.36 - 0.55, P < 0.05) measurements excluding correlations with calcaneal SOS and trochanteric BMD. The ability of the mandibular variables to discriminate between normal and osteopenic/osteoporotic cases was assessed by calculating: specificity (ranging from 31 to 81 %), sensitivity (ranging from 21 to 93 %), negative and positive predictive values (ranging from 47 to 83% and 40 to 79%, respectively). Conclusion: MCI is a simple three-graded classification of changes in the cortex but is not able to distinguish normal and osteopenic/osteoporotic postmenopausal edentulous women. The efficacy of the panoramic-based mandibular indices in diagnosing osteopenia/osteoporosis is low to moderate.