Three-dimensional modeling of the TMJ based on CT images

Abstract

The purpose of this study was to establish the threshold CT value for reconstructing 3D-CT TMJ images. In this study, CT scans were performed on 10 subjects and a dry skull. First, to identify the characteristics of the system used in this study, three-dimensional (3D) surface models were constructed based on the data obtained under three threshold CT values (+255, +400, and +600 Hounsfield Units (HU)). To make a standard model, 3D-surface images of the dry skull were also scanned by a noncontact 3D laser scanner. When the CT-value threshold was low (+255 HU), the fossa and condyle partially overlapped in reconstructed 3D images. Next, the mean threshold CT value for all 10 subjects was calculated by taking into account the results of reconstruction with a CT value of +580 HU. The present results suggest that an appropriate 3D shape and positional relationship between the fossa and condyle can be obtained by setting the CT value at +530 HU as a lower threshold. However, it is also important to clarify the proper threshold for the CT value at each anatomic location.