Low body mass index as a risk factor for the onset of porosity of the mandibular bone in the elderly

Objective: To investigate whether a low body mass index (BMI) has a significant relationship with mandibular bone porosity progression by conducting a mandibular inferior cortex (MIC) classification in elderly Japanese people. Material and Methods: A total of 266 study subjects, aged 70 at baseline, were recruited for this study, conducted from 1998 to 2007. The subjects were divided into two groups according to changes in the MIC on serial panoramic radiographs during this nine-year study period: A no change group (MIC-NC) and a change group (MIC-C). All subjects in the MIC-C showed changes trending toward greater fragility. We evaluated the BMI at baseline. Logistic regression analysis was performed to assess the relationship between the MIC condition during the nine-year period (0: MIC-NC, 1: MIC-C) and BMI (kg/m2) adjusted for gender, current health status (CHS), and smoking habit (SH) at baseline. Results: The mean and standard deviations of the BMI at baseline in the MIC-NC and MIC-C were 22.8 ± 2.1 and 21.8 ± 2.5 kg/m2 for males and 23.1 ± 2.9 and 21.9 ± 2.4 kg/m2 for females. There was a significant relationship between the MIC condition and the BMI in both males (p=0.04) and females (p=0.01). The logistic regression analysis revealed a significant association between the MIC condition over the nine-year period and the BMI (OR=0.84, p=0.003), which was adjusted depending on the gender (OR=5.18, p=0.000), CHS (OR=0.53, p=0.015), and SH (OR=4.15, p=0.002) at baseline. Conclusion: A low BMI carries a risk of developing mandibular bone porosity by measuring the MIC condition in panoramic radiographs.