2018 Volume 31 Issue 3 Pages 225-231
Objective : This study examined the meaning of screening of bone density on panoramic radiography by investigating the correlation between the depiction of the mandibular canal on a panoramic radiograph and bone density, as evaluated on a computed tomography (CT) image of the mandibular molar area.
Materials and Methods : This retrospective cohort study comprised 99 patients aged 50 years or older who underwent panoramic radiography and CT imaging. A total of 147 sites were included, comprising mandibular molar areas ; 70 sites were partially or fully edentulous with respect to the mandibular molars, and 77 sites showed no defect in the mandibular molars. Depiction of the mandibular canal on panoramic radiography was classified into three types : typeⅠ, mandibular canal visible in superior and inferior walls ; typeⅡ, mandibular canal visible in inferior and invisible in superior walls ; and typeⅢ, mandibular canal invisible in superior and inferior walls. In addition, the correlation between the mandibular canal depiction on panoramic radiography and bone density evaluated by CT images of the mandibular molar area was investigated.
Results : In the case of a panoramic radiograph showing a decrease in depiction of the mandibular canal, cortical bone and cortical bone width on the buccal side and lower border side of CT decreased. In addition, although there was no difference in the CT value within the mandibular canal due to depiction of the mandibular canal, a significant difference was found in the CT value of the outer circumference of the mandibular canal.
Conclusion : The ratio of the width of the cortical bone, as well as the CT value around the mandibular canal, both decreased when mandibular canal depiction on panoramic radiography was unclear. These results indicate that the depiction of the mandibular canal on panoramic radiography enables screening of bone density for dental implant therapy.
