The Relationship Between Mandibular Deviation And The Structure Changes In Temporomandibular Joints

Purpose:Research shows that there is a close relationship between mandibular deviation and temporomandibular joint internal derangement. The purpose of our study was designed for exploring the relationship between mandibular deviation and the structural changes in temporomandibular joints by quantitative analysis of frontal cephalometric radiographs, sagittal and coronal MRI images of the patients with mandibular deviation. Then evaluating the cranial facial morphology, the differences of mandibular condyle positions, temporomandibular joint disc positions between the two sides of TMJ.It will contribute to further understanding of relationship mandibular deviation and TMJ.Methods:A total of13patients with mandibular deviation were included (male2, female11, age18.91±5.58).The frontal cephalometric radiographs were acquired, and were analyzed by applying computer software to access the cranial facial morphology. The sagittal and coronal MRI was performed in mouth closed position, depicting the anatomical landmarks, building the reference plane,analysing the TMJ of two sides. By comparing the index of cranial facial morphology, the displacement of temporomandibular joint disc and mandibular condyle between two sides in the paired samples test, we try to find out whether there is a significant difference. Spearman correlation test were applied to analysis to find out whether there is correlation between the scale of mandibular deviation and the TMJ disc displacement and mandibular condyle displacement.Results:(1) The character of cranial facial morphology:The ANS-Mid, Ul-Mid, L1-Mid, Men-Mid is0.45±1.19mm,1.01±1.94mm,2.92±1.84mm,4.62±3.05mm, the angle between Lo-Lo’and FMxP, FOP, FMdP is-0.15±0.96°,0.87±1.93°,1.17±2.07°. The Co-Go, Go-Me, Co-Me of the deviated side reduced:4.49±3.47mm (p<0.01),5.45±7.45mm (p<0.05),7.75±6.95mm (p＜0.01), especially obvious in Co-Go.(2) The character of TMJ(the sagittal view):The difference of joint space index between two sides is-7.56±21.47(p>0.05).The a of deviated side is greater than the normal side, the difference of them is38.80±34.48°(p<0.01).And the correlation between them is:0.609(p<0.05).(3) The character of TMJ(the coronal view):The e/d of the deviated side increased0.10±0.15(p<0.05),the f/d of the deviated side decreased0.17±0.22(p<0.05).(4) The symmetry analysis of TMJ:The g/AB, h/Tp-O of the deviated side increased:0.00±0.08,0.12±0.60(p>0.05).The b/AB of the deviated side decreased0.14±0.16(p<0.05), the a/Tp-O of the deviated side increased0.52±0.53,(p<0.01).(5) The correlation analysis of TMJ:the correlation between a of the deviated side and Me, FMdP, Co-Gob,Go-Meb, Co-Meb is:0.866,0.779,0.745,0.673,0.861,(P＜0.01).The e/d, f/d, JSI of the deviated side had no correlation with the index of cranial facial morphology.the a, e/d, f/d, JSI of the normal side had no correlation with the index of cranial facial morphology.Conclusions:(1) It exists asymmetry concerning to two sides of mandible in this sample, especially obvious in terms of height of mandibular ramus.(2) There is no asymmetrical displacement of mandibular condyle on both sides of mandibular deviation patients. And the scale of mandibular deviation has no relation to the position of mandibular condyle.(3) The TMJ discs of all mandibular deviation patients have the anterior disc displacement. The deviated side is much affected than the normal side. The TMJ disc of deviated side is more likely to be anterolateral and the TMJ disc of the healthy side is more likely to be anteromedial.(4) The TMJ disc displacement of the deviated side is significant related to the scale of the mandibular deviation.It is a positive correlations. But there is no significant correlation between the scale of mandibular deviation and the TMJ disc displacement of the normal side.