Establishment Of Dynamic Images And Movement Traces Of Mandible And TMJ And The Initial Clinical Application

Mandibular movement is a complex phenomenon involving the mandible,masticatory muscles, and temporomandibular joint (TMJ). It is central to mastication,swallowing, and linguistic function. In clinical practice, abnormalities in mandibularmovement are reliable indicators of mandibular system disease and changes in motioncan be used to evaluate treatment effect. However, these techniques are limited toaccurately tracking mandible and temporomandibular joint movement.With its width16centimeters (cm) of anatomic coverage,320-row CT can scan themandibular system in a single gantry rotation. It can also construct the stereoscopicstructure of human organs, and disclose the functional status and blood flow of thewhole organ. Currently, it is the only CT that can truly achieve dynamic volumeimaging (i.e. four-dimensional dynamic observation of internal structure of humanbody). In this study, we established the dynamic images and movement traces ofmandible and TMJ with the specific merit of320-row CT, with the aiming at developinga new approach to diagnose the diseases such as mandible/condylar fracture andtemporomandibular joint disorder and evaluate the treatment effectiveness.I. Dynamic images of mandible and TMJObjective: To establish dynamic images of mandible and TMJ using320-rowcomputed tomography (CT)(Toshiba, Aquilion One). Methods: A non-metallic,stepwise mouth gag was placed between mandibular and maxillary incisors to controlmouth opening (0.5-cm increments) in10normal volunteers. A320-row CT Joint-Move&Shot sequence was used to dynamic scanning with an exposure taken after eachincrement. Dynamic reconstruction was used to establish volume data. Results:Dynamic images of mandible and TMJ in a rest state and in a state of mandibularmovement from multi angles and in different planes demonstrated differences on healthy subjects. The effective dose per scan was approximately17%of the16-slicespiral CT. Conclusions: Dynamic images of mandible and TMJ can be achievedthrough320-row volume CT scanning, which may provide a new approach fordiagnosis of TMD and other conditions, and assessment of treatment effects.II. Movement traces of mandible and TMJObjective: To establish movement traces of mandible and TMJ using320CT and soft.Methods: A non-metallic, stepwise mouth gag was placed between mandibular andmaxillary incisors to control mouth opening (0.5-cm increments) in10normalvolunteers. A320-row CT Joint-Move&Shot sequence was used to dynamic scanningwith an exposure taken after each increment. Dynamic reconstruction was used toestablish volume data. Movement traces of mandible and TMJ can be achieved through320CT scanning and soft of Macromedia Flash8,Adobe Photoshop CS3. Results:The movement traces of madibular opening and closing were separated in10normalvolunteers, which were deflected to left when opening. The movement traces of twocondylaris presented as smooth arc curve pointing to anterior inferior, and themovement traces of opening and closing were inosculated. Conclusions: Mandibulartraces separated and deflected to left and right when opening and closing. Themovement traces of opening and closing of bilateral condylaris were inosculated andbilateral symmetry.III. The clinical application of dynamic images and movement traces1. Post-operative evaluation of bone fractureBilateral condylaris fracture after operation: The movement traces of the opening andclosing of mandible showed a8shaped curve. The movement traces of right condylarshowed inverted arc shaped curve, and movement traces of left condylar was smooth.The movement traces of bilateral condylaris opening and closing were separated. Themain reasons were as follow: The left condylar didn't undergo operation, the rupturedcondylar shifted inward, the mandibular ramus was shorten, and the bilateral condylariswere asymmerty on anatomy; The loss of adhesion of muscle and ligament of left condylar induced the unbalance of pulling strength during the opening and closingprocess.Left condylar fracture after operation: The movement traces of right condylar showedL shaped curve, and the maximum opening only reached posterior inferior point ofarticular tubercle. The movement traces of left condylar was smooth, but the motionamplitude was less than right side. The movement traces of mandible shifted to left side.The three movement traces were inosculated. The320-row CT examination wasperformed after two weeks of operation. The main reasons were as follow: The fractureof left condylar didn't heal at that time, the ruptured condylar was partly separated andcould not move as a whole bone, and the forward gliding of condylar was limited.2. The diagnosis of temporomandibular joint disorder: The movement traces ofmandible opening and closing showed inverted L shaped curve. The movement traces ofright condylar presented as curving line, left condylaris presented as smoothness arccurve, and the movement traces of opening and closing were inosculated. Theconfirmed diagnosis of TMD could be achieved by dynamic images and movementtraces.3. The diagnosis of anterior disc displacement: The mixture of gadolinium contrastagent and diodone was injected into the superior cavity of temporomandibular joint, andthen320-row CT and MRI were performed. The diagnosis of anterior disc displacementwas establised by dynamic images, movement traces and arthrography.Conclusions Dynamic images and movement traces of mandible and temporo-mandibular joint can be achieved through320-row volume CT scanning, which mightprovide a new approach for diagnosis of temporo mandibular joint disorder and otherconditions and can be used to evaluate of treatment effects.