| Objectives:1. To observe structures of temporomandibular joints (TMJs) of young people with normal occlusion by Cone Beam Computerized Tomography (CBCT).2. To investigate the differences of some measurement methods for temporomandibular joint space, which was supposed to provide basis for clinical diagnosis and treatment of some oral diseases.3. To highlight the potential application of CBCT in certain medical research.Materials and methods:1. NewTom VG CBCT was employed to scan skull specimens, which were marked by special metal sheets. NNT-Viewer CBCT was applied bo reconstruct images and measure distances between different markers. Then it is compared distances showed in layers with that actual ones between several markers.2. Fifteen volunteers from Kunming Medical University, aged18-23, were examined for individual normal occlusion with no TMJ. Followed CBCT imaging, the software was used to reconstruct layers and to set up a way to measure and record TMJs by axial position, sagittal position, coronal position, and oblique position perpendicular to and parallel to the condyle long axis.3. To measuree tempor-omandibular joint spaces, there were three ways to follow, in perpendicular to the condyle long axis position:1) drew mark lines through the midpoint of external auditory foramen, which were paralleled to a line from the lowest point of the articular eminence to the vertex of the external auditory canal;2) drew mark lines through the lowest point of the articular eminence and the vertex of the external auditory canal;3) drew mark lines through the lowest point of the articular eminence and the median of external auditory meatus. Comparative studies on above three methods were taken subsequently.Results:1. The calculated results of CBCT was similar with that tested in skull specimens (P>0.05).2. The radius distances from left and right side of the condyle to the sagittal midline according to CBCT axial images were62.30±3.12mm and62.15±3.18mm (P>0.05), which was no statistical difference.3. The results of sagittal joint gap among groups showed statistical difference (p<0.05). There was no difference between the result of30°space (3.10±0.62mm) and90°space (3.09±0.63mm), both which were greater than that of60°,120°, and150°. The results of the joint space perpendicular to the oblique of the condyle long axis also showed statistical difference (p<0.05). The result of30°space (3.52±0.58mm) was greater than that of90°space (3.06±0.70mm), which was greater than that of60°,120°, and150°. The results of the joint gap between the coronal position and the oblique position which is paralleled to condyle long axis, showed no statistical differences among groups. Other results of comparison between left and right-sided condyle showed no statistical difference (P>0.05).3. The results of differnet marker-line measurements for three joints space groups showed difference (p<0.05). The results of measuring the joint space with30°and60°showed difference between that calculated by first method and second or third method (p<0.05). The results of measuring the joint space with90°,120°, and150°, showed no difference among that calculated by three method (P>0.05).Conclusions:1. The results of measurements on different aspects showed no difference between that calculated by CBCT and that tested in skull specimens.2. CBCT could image axial, sagittal, coronal, and oblique perpendicular to and parallel to the condyle long axis of TMJ, and with its software, analyze imaging data subsequently. It is preferred to choosing oblique position parallel to or perpendicular to the condyle long axis than coronal and sagittal positions in certain joint structure measurement.3. CBCT could image the condyle in the glenoid fossa. CBCT could produce good images for the condyle in the glenoid fossa. It performs better via first method than others in locating and measuring temporomandibular joint spaces. |
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