| Objective: This study measured the anteroposterior diameters of the condylar process, mediolateral diameters of the condylar process, distances condylar process/midsagittal line, angles condylar process/midsagittal line, anteroposterior differences of the condylar process, anterior spaces and posterior spaces of the condylar process and anterior spaces, posterior spaces and superior spaces of temporomandibular joint with CBCT(Cone Beam computed tomography) and its matching software Invivo Dental 5.0 to investigate the condylar process position and its symmetry of Class II Division 1 subdivision patients, aiming to help the diagnosis and design of malocclusion.Materials and methods: According to the inclusion criteria, thirty patients from January 2013 to January 2014 in General Hospital of Shenyang Military Dental Clinic, ranging from 12 years to 25 years of age(mean:17.1 years) with Class II Division 1 subdivision malocclusions were selected for the experiment, including eight male patients and thirteen female patients. The patients were all in permanent dentition. Use KaVo 3D CBCT produced in German to scan the cranio–maxillofacial of patients and obtain the images of intercuspal position. All of the images were obtained from the same radiologist. The output format of images was DICOM 3.0.Use Invivo Dental 5.0 image analysis system to process the data. First, enter the CBCT data which the format were DICOM 3.0 into Invivo Dental 5.0 software,adjust the images, and then select the appropriate levels of the images to measure.Enter the TMJ interface of the Invivo Dental 5.0 software, choose the reconstruction scales, and adjust the images of coronal section to make both sides symmetric. In the images of cross section, choose the level with the maximum mediolateral diameters of the condylar process at first, determine the central point of bilateral condylar process in cross section in this level, and make a straight line across the midpoint of nasal septum and foramen magnum as the midsagittal line of this level. Measure the ateroposterior diameter, mediolateral diameter, distance condylar process/midsagittal line, angle condylar process/midsagittal line, distance between anterior space and posterior space of bilateral condylar process following the Vitral Method. The anteroposterior difference was the distance between the geometric center of the right and left condylar processes as reflected on the midsagittal line, side I was defined as0. For side II, if the geometric centers situated anterior to the side I, they were defined as positive, and those posterior to it were defined as negative. In the basic of cross section imaging, Invivo Dental 5.0 can obtain the sagittal tomogramphic images of bilateral temporomandibular joint which were vertical to the plane used to study the symmetry of condylar process automatically, the width was 40 mm, and the thickness was 3.0 mm. Choose the intermediate level as the measurement plane.Measure the anterior space and posterior space of temporomandibular joint with the Kamelchuk Method. Quantize the sagittal positions of condylar process within the glenoid fossa by calculating the values of ln(P/A).If ln(P/A) is greater than 0.25,it suggested that the condylar process was in the anterior position; ln(P/A)was less than-0.25, it suggested that the condylar process is in the posterior position; and if ln(P/A)was between-0.25 and 0.25, it suggested that the condylar process was in the concentric position. Measure the superior spaces of temporomandibular joint on the basis of measuring anterior spaces and posterior spaces of temporomandibular joint.Enter the data into SPSS19.0 to make a statistical analysis. Paired Student t tests were used for the anteroposterior diameter, mediolateral diameter, distance condylar process/midsagittal line, angle condylar process/midsagittal line, and anteroposteriordifference of the condylar process. Independent-sample T tests were used for the values of ln(P/A)in both sides. Paired T tests were used for bilateral superior spaces of temporomandibular joint, if P value was less than 0.05, it suggested that there is a statistically significant difference.Results: 1.Condylar symmetry: the anteroposterior diameter, mediolateral diameter, distance condylar process/midsagittal line, angle condylar process/midsagittal line, and anteroposterior difference of the condylar process in side I and side II were no statistically significant differences. 2.Condylar position:mean value of ln(P/A)was 0.254 in side I and 0.259 in side II, P value was 0.884,the bilateral condylar processes was in the anterior position and showed no statistically significant differences. The mean value of superior spaces in side I and3.155 in side II,P value was 0.013, and the results showed that there was a statistically significant difference.Conclusion: The bilateral condylar processes of Class II Division 1subdivision patients were symmetrical in cross section and in the anterior position in sagittal section; the position of condylar process in side II was lower than side I. |
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