Digital panoramic radiography and cone-beam CT as ancillary tools to detect low bone mineral density in post-menopausal women.

Objectives: To evaluate the usefulness of the mandibular cortical index (MCI) obtained by digital panoramic radiography (DPR) and by panoramic reconstruction (PR) of cone-beam CT (CBCT) with three different slice thicknesses for the screening of low bone mineral density (BMD) in post-menopausal women.

Methods: Two trained oral and maxillofacial radiologists assessed the MCI based on the morphology of the mandibular bone cortex (classified as C1, C2 or C3). The DPR and PR of CBCT with slice thicknesses of 5, 15 or 25 mm were compared to the BMD obtained by dual-energy X-ray absorptiometry (DXA) in post-menopausal women. Measures related to accuracy were calculated with MedCalc software. The confidence interval was set at 95%.

Results: 54 women (mean age 58.70 ± 7.35 years) participated in the study. The sensitivity and specificity values obtained for DPR were 52.6% and 56.2%, respectively, and values for PR of CBCT with 5, 15, and 25 mm slice thicknesses were 63.1% and 43.7%, 50.0% and 50.0%, and 52.6% and 62.5%, respectively. For the tools evaluated, the positive likelihood ratio ranged from 1.00 to 1.40 and negative likelihood ratio from 0.76 to 1.00. The positive predictive value (PPV) ranged from 70.4 to 76.9% and the negative predictive value (NPV) from 29.6 to 35.7%. Among the examinations, the highest value for area under the curve (AUC) was obtained for CBCT with 25 mm slice thickness (57.6%).

Conclusions: The MCI calculated by DPR and CBCT differed with regard to accuracy. Within the limitations of this study, the PR of CBCT with 25 mm slice thicknesses seems to be the most accurate among the examinations evaluated. Should the dentist be attentive, DPR and CBCT may be useful tools for the screening of low BMD in post-menopausal women, facilitating their timely referral for further assessment.