Mandibular Inferior Cortex Erosion on Dental Panoramic Radiograph as a Sign of Low Bone Mineral Density in Postmenopausal Women

Objective To examine the role of the panoramic mandibular radiograph in the diagnosis of low bone mineral density (BMD) in postmenopausal women. Methods A cross-sectional study including volunteer women aged over 40 years in amenorrhea due to ovarian failure for at least 12 months, who were cared for at the climacteric outpatient clinic of a university hospital in the city of Cuiabá, in the state of Mato Grosso, Brazil. The panoramic radiographs were evaluated using a specific software. Two aspects were analyzed in the mandibular panoramic radiograph: a qualitative aspect regarding the shape of the mandibular cortical bone, and a quantitative aspect regarding the width of the mandibular cortical bone. The morphology of the mandibular cortical bone in the digital panoramic radiograph was determined bilaterally by the observation of the bone structure between the mental foramen and the base of the jaw. The mandibular cortical bone was categorized into three groups. The mental index (MI) was used to evaluate the thickness of the mandibular cortical bone through a perpendicular line drawn from the base of the mandible at the height of the center of the mental foramen, with another line drawn tangent to the inferior border of the mandible, and a third line parallel to the line at the superior border of the mandible. The MI data are expressed in millimeters, with a normal value of 3.0 mm. The densities of the lumbar spine and femur, expressed in g/cm(2), were categorized as normal, osteopenia or osteoporosis. Results The agreement index between the MI and the BMD of the lumbar spine was good (Kappa = 0.718), but the same index between the MI and the BMD of the femoral neck was poor (Kappa = 0.443). An excellent agreement occurred when the mandibular cortical index (MCI) was compared with the BMD of the lumbar spine (Kappa = 0.912). The agreement between MCI and the BMD in the femur was moderated (Kappa = 0.579). Conclusion The radiomorphometric indices evaluated in the mandibular panoramic radiograph are capable of identifying postmenopausal women with low mineral density in the mandible, and the results can be used to refer these women to appropriate medical investigation and/or treatment.