Potential Risk of Asymptomatic Osteomyelitis around Mandibular Third Molar Tooth for Aged People: A Computed Tomography and Histopathologic Study

The purpose of this study was to explore the relationship between bone mineral density and histopathological features of mandibular alveolar bone evaluated quantitatively by Hounsfield units [HU] and by histopathology in human subjects. Fifty-six mandibular molars were extracted in 50 patients. Computed tomography was obtained preoperatively, and a cortical bone biopsy was obtained on the extracted sites for histopathological evaluation. The mean cortical and cancellous bone radiodensity was 1846 ± 118 HU and 926 ± 436 HU, respectively. There was no correlation between age and cortical bone HU (r = -0.004, P = 0.976); however, the correlation between age and cancellous bone HU was significant (r = 0.574, P<0.0000). Significant differences in the cancellous bone between young (0-30 years), middle (31-60 years) and old patient groups (61< years) were evident (P<0.05), whereas the cortical bone presented no significant differences. The histopathological evaluation showed that the young patient group had relatively few osteomyelitis, whereas the old patient group showed 100% focal sclerotic osteomyelitis regardless of the fact that the patients had no clinical symptoms. The mean osteocyte number/unit bone area was 170.7 ± 82.2. Negative correlation between age and osteocyte number was significant (r = -0.51, P<0.0001). Mean lacunae numbers/unit cortical bone area were 413.1 ± 130 with non-significant negative correlation (r = -0.257, P = 0.056). The mean empty lacunae numbers/cortical bone were 242.5±145, with no correlation (r = 0.081, P = 0.559). The young patients had high osteocyte number, whereas the old patients showed reduction of the osteocytes in the cortical bone (P < 0.05). Bone quality might correlate better to viable cell numbers, which influenced the osseous healing. It is suggested that the outermost layer of cortical bone may have lost its cellular activities over the years due to chronic infection, which may have provoked sclerotic changes in the cancellous bone around tooth.