Research On Condylar Morphology In Patients With Prolonged Unilateral Posterior Teeth Loss With Cone-beam Computed Tomography

Objective The study aimed at using cone-beam computed tomography(CBCT)to study the condylar morphology of patients with prolonged unilateral posterior teeth loss,to study the influence of prolonged unilateral posterior teeth loss on bilateral condylar morphology,to explore the influence of different load on condylar reconstruction,so as to provide clues.for clinical and scientific research work on temporomandibular joint.Methods Objects of this study were selected from patients treated in Zhejiang Chinese Medical University Affiliated Dental Clinic and Hangzhou Bofan Dental Clinic from January 2010 to April 2015.The individual normal occlusion group included 30 patients,15 male cases were male,15 cases were female,aged 20 to 50.Then selected 30 patients with prolonged unilateral posterior teeth loss,15 cases were male,15 cases were female,aged 20 to 50.A11 the patients were informed consent.With the CBCT scanning and imaging examining system,the images were storaged in standard Dicom 3.0 format.Mimics15.0 was used to record the datas.Set the CT segmentation threshold,bone surface contour was automatically generated.After determining the upper and lower bounds of condylar,the surrounding tissue were removed through the Edit Mask command gradually.Using the command of Calculate 3D from Mask,three-dimensional images of the mandibular condylar were reconstructed.Measurement projects of condylar morphology include:Condylar Volume(Volume 1),Condyle Head Volume(Volume 2),Transversal Plane Area,Height of Condylar,Height of Condylar Head,Medial-lateral Diameter,Anteroposterior Diameter,average Condylar bone density(Hounsfield Unit 1),average bone density of Condylar Head(Hounsfield Unit 2),average bone density of Condylar transverse Plane(Hounsfield Unit 3).Measure and record all the data.In order to avoid the error between different gaugers,all the work were completed by the same gauger.Each project was measured for 2 times,with the interval of 2 weeks,and figured up the average.The statistical analysis was done with software SPSS 22.0.all the datas received the test of normality.If the datas were normal distribution descript them with the mean value(X)and the standard deviation(S).If the datas were not normal distribution descript them with median(M)and quartile range(Q).The datas were analyzed by Wilcoxon rank-sum test.The difference between both sides of normal group were analysed by Paired-T test.The difference between bilateral sides of teeth-loss group were analysed by Paired-T test too.The difference between teeth-loss group and normal group were analysed by independent sample T test.The standard was α<0.05,P<0.05 meaned the difference was statistically significant.Results1 In comparison of both sides in normal group,all measurements’P value were greater than 0.05.There is no statistically significant difference between both sides of the normal group.2 In comparison of bilateral condylar morphology in teeth-loss group,there is statistically significant difference.It means both sides are not symmetrical.Differentials between teeth-loss side and contralateral side include these condylar morphology measurement projects:Condylar Volume-553.03±395.51mm3,Volume of Condyle Head-298.51±257.85mm3,Height of Condylar-1.94±1.92mm,Height of Condylar Head-0.74±1.59mm,Anteroposterior Diameter-0.39 ± 0.93mm,average bone density of Condylar-73.18±86.22,average bone density of Condylar Head-125.67±81.04,Transversal Plane Area26.12±37.26mm2,average bone density of Condylar Transversal Plane76.17±56.56.3 In comparison of the same aged normal group and teeth-loss side in unilateral teeth-loss group,there are 6 measurements whose P<0.05.Condylar of teeth-loss side was smaller than normal group.They are Condylar Volume 1242.80±134.04mm3,Volume of Condyle Head 556.41±84.41mm3,Anteroposterior Diameter 5.64±1.08mm,average bone density of Condylar 489.29 ± 35.35,average bone density of Condylar Head 450.48±74.79.4 In comparison of the same aged normal group and contralateral side in unilateral teeth-loss group,there are 4 measurements whose P<0.05.Condylar of contralateral side was larger than normal group.They are Condylar Volume 1795.83±423.91mm3,Volume of Condyle Head 854.92 ± 297.56mm3,Anteroposterior Diameter 6.03±1.10mm,average bone density of Condylar Head 576.15 ± 56.28.Conclusion1 Bilateral condyle of normal occlusion people are symmetry.2 After prolonged unilateral posterior teeth loss,adaptive reconstruction occurred in the bilateral condyles;and condyle of missing teeth side was smaller than the contralateral side.3 In comparison of the same aged normal group and teeth-loss group,condyle of missing teeth side was smaller than the normal group,and condyle of normal group was smaller than contralateral side in teeth-loss group.