Measurement And Analysis Of Indexes Of Mandibular Three-dimensional Shape In Patients With Hemimandibular Elongation

Objective:Reconstruct three-dimensional image of mandibula for patients with hemimandibular elongation by CBCT.To analyze the morphological characteristics of mandibula for patients with hemimandibular elongation using and calculate reference ranges for normal and abnormal mandibula.Methods:Cone-beam computed tomography data were stored acconding medical digital image communication standard.Mandibula three-dimensional reconstruction was performed using Mimics 15.0.For 46cases of hemimandibular elongation of patients were analyzed the positioning accuracy on the selecting 23 landmarks in mandibe by linear correlation and linear regression analysis.46 patients with hemimandibular elongation?the disease group?and 46 normal controls?the control group?were included in this study.The location marks were used to measure line distance and volume of mandibula,and the results were statistically analyzed.Results:?1?the Ma and Mp points showed incosistencies in the X axis(r_Ma=0.9415/b_Ma=0.9645;r_Mp=0.9656/b_Mp=1.0544);the Gn and JmN point showed inconsistent in the Z axis(r_Gn=0.9834/b_Gn=1.0538;r_JmN=0.9354/b_JmN=0.9782).However,CoT?Co A?Co?La?Lp?MN?Ra?Rp?Ag?Go?Gn?M1S?M1I?M1B?M1L?Ca S?Ca I?Ca B?Ca L?JlN points expressed good consistent.?2?There was no statistical difference in measurements between two groups?p>0.05?.For the disease group,the lesion side had significantly greater measurements of WC,WN,HC,LAR,LHR,HM1,HAC,VT,VC,VAR,VB2 and VB3 than the normal side?p<0.05?.The differences in other indexes were not statistically signifcant?p>0.05?.?3?Obtained reference ranges for normal mandibula with IM3DS between 1 and 6 were 0.5797-0.8271,0.5323-0.7087,0.1377-0.2000,0.1405-0.1895,0.1387-0.1427 and 0.0606-0.0802.Reference ranges for abnormal mandibula were 0.3862-0.7092,0.3351-0.6581,0.0166-0.3040,0.1002-0.1900,0.0968-0.1604,and 0.0914-0.1416.Conclusions:?1?The 23 landmarks showed good consistency,and it can provide basis for us,when we research the mandible shape for patients with hemimandibular elongation.?2?The increase in the volume of mandibula in patients with hemimandibular elongation is mainly at mandibular ascending branch and back of mandibular body with the same development trend as normal mandibula.?3?IM3DS can rapidly and effectively evaluate mandibular shape for patients with hemimandibular elongation,so as to clarify lesion range and degree and provide references and guidance for clinical diagnosis.