Magnetic resonance imaging-verified temporomandibular joint disk displacement in relation to sagittal and vertical jaw deformities

This retrospective study was designed to analyze the relationships between temporomandibular joint (TMJ) disk displacement and skeletal deformities in orthodontic patients. Subjects consisted of 460 adult patients. Before treatment, lateral cephalograms and TMJ magnetic resonance imaging (MRI) were recorded. Subjects were divided into six groups based on TMJ MRI according to increasing severity of TMJ disk displacement, in the following order: bilateral normal TMJs, unilateral disk displacement with reduction (DDR) and contralateral normal, bilateral DDR, unilateral disk displacement without reduction (DDNR) and contralateral normal, unilateral DDR and contralateral DDNR, and bilateral DDNR. Subjects were subdivided sagittally into skeletal Class I, II, and III deformities based on the ANB (point A, nasion, point B) angle and subdivided vertically into hypodivergent, normodivergent, and hyperdivergent deformities based on the facial height ratio. Linear trends between severity of TMJ disk displacement and sagittal or vertical deformities were analyzed by Cochran–Mantel–Haenszel test. The severity of TMJ disk displacement increased as the sagittal skeletal classification changed from skeletal Class III to skeletal Class II and the vertical skeletal classification changed from hypodivergent to hyperdivergent. There were no significant differences in the linear trend of TMJ disk displacement severity between the sexes according to the skeletal deformities. This study suggests that subjects with skeletal Class II and/or hyperdivergent deformities have a high possibility of severe TMJ disk displacement, regardless of sex.     

术前正畸对颞下颌关节关节盘及髁突位置和形态的影响

目的 探讨术前正畸对颞下颌关节关节盘及髁突位置和形态的影响。方法 选择骨性错畸形患者30例,在颞下颌关节磁共振图像上进行测量。通过关节间隙测量,判定髁突位置;通过髁突头长度、宽度和高度测量,判定髁突形态;关节盘位置和形态由直接观察判定,采用SPSS 24.0软件包对所得数据进行统计学分析,比较骨性Ⅰ、Ⅱ和Ⅲ类畸形患者在术前正畸前、后关节盘及髁突位置和形态变化。结果 术前正畸前、后关节间隙和关节间隙指数,髁突头长度、宽度和高度、关节盘前移角及关节盘形态差异均无统计学意义（P>0.05）。结论 术前正畸治疗不会导致骨性错畸形患者关节盘及髁突位置和形态改变。     

骨性Ⅲ类偏颌患者髁突与(牙合)平面特征的CBCT研究

目的 利用锥形束CT(CBCT)测量分析骨性Ⅲ类偏颌患者髁突及(牙合)平面特征。方法 选取符合纳入标准的骨性Ⅲ类成年患者40例,所有个体按照颏下点偏离正中矢状面距离进行分组,分别测量各组左右两侧(牙合)平面角、髁突位置及形态,并对数据进行统计学分析。结果 骨性Ⅲ类偏颌患者的偏侧与对侧相比,(牙合)平面角、关节前间隙、关节上间隙、关节外间隙及髁突内外径差异有统计学意义(P<0.05),偏侧关节后位所占比例较大,下颌骨偏移量与偏侧髁突前间隙及对侧(牙合)平面角均呈正相关(P<0.01)。骨性Ⅲ类非偏颌患者的左右两侧(牙合)平面角、髁突位置及形态指标之间差异均无统计学意义(P>0.05),关节以前位、中位为主。结论 骨性Ⅲ类偏颌患者左右两侧(牙合)平面角、髁突位置及形态不对称,偏侧(牙合)平面角及髁突内外径较小,髁突向后下内方移位,且偏颌程度与(牙合)平面角及髁突位置之间存在相关性。     

骨性Ⅲ类下颌偏斜患者颞下颌关节形态位置及上颌骨特征的三维评估

目的 ：研究双侧下颌角点垂直向不调的骨性Ⅲ类下颌偏斜患者颞下颌关节的形态、位置及上颌骨特征。方法 ：对79例成人骨性Ⅲ类错畸形患者进行颅面部螺旋CT扫描,采用ProPlan CMF3.0三维分析软件对颞下颌关节进行三维重建,根据颏点偏斜程度分为对称组（S组：n=24）和偏斜组（n=55）。偏斜组中,根据双侧下颌角点有无垂直向不调分为2组,ASV组—双侧下颌角点存在垂直向差异（n=27）,ASNV组—双侧下颌角点不存在垂直向差异（n=28）。测量7项髁突形态、位置指标以及9项上颌骨相关指标,采用SPSS 22.0软件包对数据进行统计学分析。结果：偏斜组的偏斜侧髁突长度均短于偏斜对侧,两侧差值均大于对称组,上颌骨均存在自身不对称以及不同程度的三维方向不调。ASV组中,偏斜侧髁突轴与水平面的角度更小,髁突前后径更小。ASNV组中,偏斜侧髁突内外径更小。方差分析和多重比较显示,ASV组和ASNV组两侧髁突长度的差值均比对称组大。ASV组和ASNV组上颌骨存在自身不对称,偏斜侧上颌骨宽度大于非偏斜侧。ASNV组更有可能存在上颌骨横向不调。ASV组上颌骨左右侧垂直向不调大于ASNV组和S组,且偏...     

Three-dimensional comparative evaluation of articular disc position and other temporomandibular joint morphology in Class II horizontal and vertical cases with Class I malocclusion:: A magnetic resonance imaging study

ObjectiveTo evaluate and compare articular disk position, condylar position, and joint spaces in Class II vertical, Class II horizontal, and Class I cases. The purpose was to assess the potential for development of temporomandibular disorders (TMDs) in the three groups.Materials and MethodsA sample of 75 cases, 25 cases in each group of Class I, Class II vertical, and Class II horizontal, were selected based on inclusion and exclusion criteria. Magnetic resonance imaging (MRI) assessments were made with a 1.5-Tesla basic system with a closed-mouth technique for evaluating articular disk position in the sagittal and transverse planes, condylar position, and joint spaces in the sagittal plane. Philips 3.0 software was used to analyze the MR images.ResultsThere was evidence of alterations in the temporomandibular joint (TMJ) morphology in both Class II vertical and Class II horizontal cases, with maximum discrepancy in Class II vertical cases. MRI evaluation suggested a tendency for antero-medial disk displacement with anteriorly positioned condyles in Class II vertical cases. The discrepancy was milder in the Class II horizontal group.ConclusionsClass II vertical cases are more susceptible to the development of TMDs and should be subjected to TMJ evaluation before starting any orthodontic treatment to intercept and prevent a mild asymptomatic TMD from developing into a more severe form. Class II vertical cases should be subjected to MRI evaluation before starting any orthodontic treatment.     

Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative controlled positioning by a positioning splint

PURPOSE: Most techniques of proximal segment positioning hinder intraoperative condyle displacement. However, merely maintaining condylar position cannot optimize the preoperative condyle-disc-fossa relationship. This study attempts to optimize condylar position in the osteotomy patient. PATIENTS AND METHODS: A study group of 23 bimaxillary operated patients had intraoperative joint positioning by positioning splint and plates (9 Angle Class II, 14 Class III). After assessing the habitual and appraising the optimized condyle position on preoperative sonograms and magnetic resonance images, positioning splints were constructed as acrylic occlusal wafers in a semi-individual articulator. Set in occlusion before adaptation of positioning plates, they were intended to move the condyles into the calculated position. Eighteen bimaxillary operated control patients had conventional plate positioning according to the habitual occlusion (9 Angle Class II, 9 Class III). Clinical follow-up, axiography, or sonography was maintained for 24 months. Preoperative lateral cephalograms were scrutinized for horizontal and vertical joint spaces and compared with the immediate postoperative radiography. RESULTS: Postoperative Class II study group patients had less dorsal and more vertical joint space and Class III patients more dorsal and vertical space compared with the controls. The study group exhibited significantly less postoperative dysfunction compared with the control group (2-way analysis of variance: P <.021, F = 9.2, alpha =.05 significance level), disc dislocation prevalence was lower (P <.07, F = 9.2), postoperative changes in condylar translation were smaller (P <.014, F = 4.9), and 8% skeletal relapses versus 22% in the controls were seen. CONCLUSIONS: A proximal segment-positioning splint effectively positioned the condyle in the desired direction, but with considerable relapse, significantly reduced postoperative dysfunction, disc dislocations, changes to the condylar translation, and incidence of skeletal relapse at 24-month follow-up.     

80 侧颞下颌关节骨性形态螺旋CT图像测量

目的揭示国人正常青年男性颞下颌关节(temporomandibular joint,TMJ)的骨性形态特征,建立该人群TMJ骨性形态参考值。方法对40例正常国人青年男性(21~24岁)的TMJ区行多排螺旋CT(multisliceCT,MSCT)扫描,在工作站上进行多平面重建(multi planar reformation,MPR)和参数测量,对结果进行统计学分析。结果反映TMJ骨性形态的各参数测量值左右侧TMJ之间无显著性差异(P>0.05),将左右侧测量结果合并得出各参数的参考值;计算各参数的变异系数显示该人群中TMJ的功能面较非功能面形态变异小,髁突纵轴倾斜角在所有的测量参数中变异系数最小(0.058);关节窝前后径(0.074),髁突左右径(0.075),髁突外1/3前后径(0.090),关节窝左右径(0.112)变异系数也比较小;在所有的测量参数中髁突垂直倾斜角、关节窝顶骨质厚度、髁突水平倾斜角变异系数最大(分别为0.663,0.638,0.390)。结论MSCT配合MPR可以实现对TMJ骨性形态进行精确而全面的测量,建立TMJ骨性形态参考值,该参考值可作为临床TMJ疾病诊断、治疗以及人工TMJ设计的参考。     

Magnetic resonance imaging of the condylar growth pattern and disk position after chin cup therapy: a preliminary study

This study was conducted on lateral cephalograms and magnetic resonance images (MRIs) obtained from 20 subjects with Class III malocclusion. Only clinically temporomandibular joint (TMJ) symptom-free subjects were included in this study. In the treatment group, a chin cup with 600 g of force was applied in 13 patients (10 girls and three boys) with a mean age of nine years. The chin cup was applied in a direction from the chin toward the TMJ. The control group consisted of seven patients (six girls and one boy) with a mean age of eight year nine months. Orthodontic treatment was not applied in the control group. Records were taken at the beginning and end of chin cup therapy from all the subjects. Measurements were made on lateral cephalograms and unilateral-left sagittal-oblique TMJ MRIs. Variables obtained at the beginning and end of the study were compared by Student's t-tests and paired t-tests. Relationships between craniofacial and TMJ variables were analyzed by correlation analysis. The mandibular corpus length was increased and condylar head angle was decreased by chin cup therapy. A positive correlation existed between activation of sagittal maxillary and mandibular growth and bending of the condylar head. This study showed that the condylar growth pattern was altered by chin cup. It may be implied that the source of improvement is adaptation of the craniofacial structures to the changes of the condylar growth pattern produced by the chin cup.     

髁突特发性吸收的临床观察

目的 通过对髁突特发性吸收（idiopathic condylar resorption,ICR）患者临床资料的回顾性分析,总结ICR的临床特点和影像学特点,探讨ICR可能的发病因素,提高诊断水平。方法 收集2007年6月—2012年7月中山大学附属口腔医院颞下颌关节病诊治中心收治的ICR患者46例,对其进行随访观察。记录患者面型、颞下颌关节症状及咬合状况;借助全景片、头颅定位正侧位片、许勒位片检查,以了解患者下颌支高度、髁突骨质破坏情况、颅面结构特征等影像学变化,借助颞下颌关节锥形束CT（CBCT）检查及造影检查,了解髁突吸收与关节盘-突结构改变之间的关系。结果 46例患者中,男4例,女42例（91.30%）,以青少年为主。患者均呈安氏Ⅱ类面型,侧貌突,侧貌不美观,下颌骨后缩,下颌支高度降低,前牙开、后牙早接触、安氏Ⅱ类错。多伴关节区弹响、杂音。X线平片显示,髁突形态变小甚至消失;下颌支垂直距离变短;头影测量呈安氏Ⅱ类高角型特征;TMJ CBCT造影示关节盘-突关系改变,尤其以关节盘穿孔较为常见,穿孔位置多在关节盘后区。结论 ICR具有独特的发病机制和临床特征。TMJ关节盘移位与ICR可能存在相关性。     

生长发育高峰前期与高峰期安氏Ⅲ类错(牙合)颞下颌关节CBCT比较分析

目的 应用锥形束CT(CBCT)分析安氏Ⅲ类错(牙合)不同CVM分期颞下颌关节(TMJ)的生长发育差异.方法 分别对60名恒牙早期均角安氏Ⅲ类患者和60名恒牙早期正常(牙合)在牙尖交错位进行CBCT扫描,按颈椎CVM分期进行分组,使用Invivo5软件对影像重建并进行数据测量.通过SPSS22.0软件采用LSD法分析比较生长发育高峰前期与高峰期的髁突生长发育差异.结果 安氏Ⅲ类错(牙合)组相比正常(牙合)组中髁突绝大多数位于关节凹前位.安氏Ⅲ类错(牙合)组CS3-CS4期与CS1-CS2期生长变化差值显示髁突上间隙、前间隙减小量、后间隙增长量与正常(牙合)组相比有统计学差异(P<0.05);髁突前后径减小量、髁突高度增长量与正常(牙合)组相比有统计学差异(P<0.05);关节窝深度、关节后斜面角减小量、关节窝前后径增长量与正常(牙合)组相比有统计学差异(P<0.05).结论 安氏Ⅲ类错(牙合)生长发育高峰期相对于高峰前期髁突绝大多数位于关节凹前位且在关节凹中的位置更靠前上.髁突垂直向发育过度,更为细长,关节凹浅而宽.     

Magnetic resonance imaging-based joint space measurements in temporomandibular joints with disk displacements and in controls

OBJECTIVE: Previous studies have discussed a posterior displacement of the condyle as a possible risk factor for the development of disk displacements (DDs) of the temporomandibular joint (TMJ). The objective of this study was to compare the posterior and anterior joint spaces in healthy TMJs with those of patients who present different forms of DDs.Study Design: The anterior and posterior joint spaces from 58 patients with unilateral or bilateral DD with reduction (DDR) or without reduction (DDNR) and from 30 healthy volunteers were measured with 3 sagittal magnetic resonance images (MRIs) from each TMJ in the maximum intercuspid position. RESULTS: Measurements of anterior and posterior joint spaces showed a good interexaminer reproducibility (rank correlation coefficients ranging from 0.88 to 0.95). Patients with bilateral DDR demonstrated a significantly more posterior position of the condyle, as compared with controls and patients with bilateral DDNR. DDNR presented a significant reduction of the anterior and the posterior joint spaces, leading to a mean concentric position of the condyle. Patients with unilateral DDR or DDNR demonstrated a greater variability of anterior and posterior joint spaces, compared with patients with a bilaterally identical type of DD. CONCLUSIONS: The data of this MRI-based clinical study indicate that different stages of disk displacements are associated with significant changes of condylar position. The variation of anterior and posterior joint spaces was influenced by the diagnosis of the contralateral joint.     

An adult case of TMJ osteoarthrosis treated with splint therapy and the subsequent orthodontic occlusal reconstruction: adaptive change of the condyle during the treatment.

This article reports treatment for a 21-year 11-month old female patient with severe osteoarthrosis of the TMJ with a special reference to adaptive changes of the condyle during the treatment. She had severe open bite with a Class II molar relationship; she had limited mouth opening, TMJ sounds, pain, and tinnitus. Lateral tomograms showed flattening and deep erosion on the left condyle, and an MRI revealed anterior disk displacement without reduction. By manipulation and splint therapy, TMJ pain and tinnitus were eliminated, then orthodontic treatment was initiated, maintaining the splint-induced position of the condyles. After 2 years of orthodontic treatment with a multibracket appliance, an acceptable occlusion was achieved with a Class I molar relationship. On lateral tomograms after treatment, bony deformation of the left condyle disappeared and adaptive remodeling was recognized with a uniform joint space in the left TMJ. However, repositioning of the disk was not achieved. Adaptive changes or functional remodeling experienced in this patient may be due to stable occlusion, uniform joint space, and the consequent biomechanical equilibrium in the TMJ.     

A hypothesis on the desired postoperative position of the condyle in orthognathic surgery: a review

It is very important to clarify the relationship between a dentofacial structure and a temporomandibular joint (TMJ) structure in orthognathic surgery. Recently, it was reported that the skeletal and occlusal patterns were associated with the TMJ morphology, including the disk position. In orthognathic surgery, some surgeons state that alterations in the condylar position from surgery can lead to malocclusion associated with the risk of early relapse, and also favor the development of temporomandibular disorders. For these reasons, several positioning devices have been proposed and applied, but now there is no scientific evidence to support the use of condylar positioning devices. There are some reasons why scientific evidence cannot be obtained; however, it also includes the question of whether the preoperative position of the condyle is the desired postoperative position. The purpose of this study was to verify the desired condylar position in orthognathic surgery, based on literature on the postoperative condylar position in orthognathic surgery. From the studies reviewed, it was suggested that the preoperative position of the condyle was not the desired postoperative position in orthognathic surgery.     

Relationship between temporomandibular joint internal derangement and facial asymmetry in women.

INTRODUCTION: Internal derangement (ID) of the temporomandibular joint (TMJ) can cause facial asymmetry. The purposes of this study were to analyze the relationship between facial asymmetry and TMJ ID by using posteroanterior cephalometric variables, and to compare the findings with the results of magnetic resonance imaging (MRI). METHODS: The sample consisted of women seeking orthodontic treatment at Seoul National University Dental Hospital who had routine posteroanterior cephalograms and bilateral MRIs of the TMJ. To eliminate the influence of condylar hyperplasia on facial asymmetry, only those with SNB angles less then 78 degrees were selected (n = 63). They were classified into 5 groups according to the results of the MRI: bilateral normal disk position, unilateral normal TMJ and contralateral disk displacement with reduction (DDR), bilateral DDR, unilateral DDR and contralateral disk displacement without reduction (DDNR), and bilateral DDNR. Fourteen variables from posteroanterior cephalograms were analyzed with 1-way ANOVA to evaluate differences among the 5 groups. RESULTS: Subjects with TMJ ID of greater severity on the unilateral side had shorter ramal height compared with those with bilateral normal or bilateral DDR or bilateral DDNR. In addition, the mandibular midpoint deviated toward the side where the TMJ ID was more advanced. CONCLUSIONS: Subjects with a more degenerated TMJ on the unilateral side might have facial asymmetry that does not come from condylar or hemi-mandibular hyperplasia.     

The prevalence of TMJ osteoarthritis in asymptomatic patients with dentofacial deformities: a cone-beam CT study

Osteoarthritis of the temporomandibular joint (TMJ) can be described as non-inflammatory arthritic condition that results in degenerative changes of the joint structures. The aim of this study was to evaluate the skeletal morphology of the TMJ in patients with osteoarthritis with severe skeletal malocclusions (Class II and Class III) and patients with Class I occlusion as controls. Cone beam computed tomography images of 45 Class I, 28 Class II and 44 Class III joints of Caucasian patients were assessed for the presence of any degenerative changes in the condyle and fossa/eminence complex as described in the research diagnostic criteria for temporomandibular disorders (RDC/TMD). In all groups, the most commonly observed features were articular surface flattening and subcortical sclerosis. A combination of features that corresponds to a diagnosis of osteoarthritis was observed in 3% Class I, 43% Class II and 20% Class III patient joints. In conclusion, degenerative TMJ changes were more common in patients with skeletal jaw discrepancies, but wide inter-individual variations can be observed even in patients with clinically similar malocclusions.     

Morphology of the temporomandibular joint in skeletal class iii symmetrical and asymmetrical cases: a study by cephalometric laminography

The aetiology of asymmetric growth in the mandible is not well understood. Previous studies have indicated that the functional lateral shift of the mandible in the period of prepubertal growth may translate to a true skeletal asymmetry, exclusively in skeletal Class III malocclusion. This asymmetry develops more characteristic features during the pubertal and post-pubertal growth periods. Early correction of a functional lateral shift of the mandible is recommended. The purpose of this study was to examine the relationship between the morphology of the temporomandibular joints and asymmetry in skeletal Class III malocclusion in adult female patients. Cephalometric and laminographic findings in 36 asymmetric skeletal Class III patients with a lateral shift of mandible (group 3) were compared to those of 25 symmetric skeletal Class I patients (group 1) and the same number of symmetric skeletal Class III malocclusions (group 2). All the patients had received no orthodontic treatment. The results showed that the TMJ of the side to which the mandible shifted showed a significantly narrower and shorter shape of the condyle head, smaller superior condylar space, and steeper eminence than those of the unshifted side.     

Association between condylar position, joint morphology and craniofacial morphology in orthodontic patients without temporomandibular joint disorders

The present study investigated condylar position and joint morphology in adolescent patients and elucidated the possible association between the joint structure and condylar position, and craniofacial morphology. Sixty-five adolescent patients were selected as subjects and their tomograms and lateral cephalograms were analysed. No significant differences in joint spaces were found between the right and left temporomandibular joints. Both the condyles in this population were located slight anteriorly in the glenoid fossa. With respect to the association between condylar position, joint morphology and craniofacial morphology, the ramus plane angle also exhibited significant negative correlations with posterior, lateral and medial joint spaces. Furthermore, there was a significant negative correlation between the gonial angle and the anterior joint space. These findings imply that the condyle was likely to show more posterior position in the glenoid fossa when the mandible exhibited clockwise rotation. In conclusion, the condyle in the adolescent subjects showed a symmetrical anterior position relative to the glenoid fossa. In addition, the joint spaces and it ratios were significantly related to the craniofacial morphology associated with vertical dimension. It is suggested that the condylar position may be affected by craniofacial growth pattern.     

Malocclusion associated with temporomandibular joint changes in young adults at autopsy

The purpose of this study was to identify variables of malocclusion that might be associated with previously reported temporomandibular joint morphologic findings. Before removing the left TMJ from each of 96 cadavers (age means equals 26.4 +/- 6.8 years), an intraoral examination was performed. Angle classification, crossbite, overbite, and overjet were evaluated. These parameters were analyzed with respect to their association with the following TMJ features: overall shape of the condyle and temporal bone, gross and histologic evidence of remodeling, and position of the articular disk. When combined with age, Angle Class II and III dentitions were associated with temporal and condylar deviation in form (DIF) (P less than 0.05) and more Class II dentitions were accompanied by histologic evidence of remodeling changes in the TMJs. Crossbite was associated with increasing presence of DIF in all components (P less than 0.01). Anterior crossbite was associated with DIF on the articular eminence (P less than 0.01). Deep overbite was more common in persons with flat condyles, open mandibular fossae, and anterior extension of the temporal articular surfaces (P less than 0.05). Abnormal overjet was more evident in those with DIF in the disk (P less than 0.05); greater overjet was associated with disk displacement (P less than 0.05). Considered together, abnormal overbite and overjet were associated with more extensive DIF on the condyle (P less than 0.05). In conclusion, malocclusion was associated with morphologic changes in the TMJ, particularly when combined with age. This evidence supports the belief that longer exposure to malocclusion may be associated with more extensive TMJ changes.     

颞下颌关节盘前移位患者关节骨形态与矢状向关节盘位置的关系

目的　利用磁共振成像（MRI）技术和锥形束CT（CBCT）分析颞下颌关节盘前移位患者矢状向关节盘位置与关节骨形态的关系。方法　对97例患者的178个颞下颌关节（TMJ）进行回顾性分析，根据矢状向MRI上关节盘的位置分成4组，即对照组（关节盘无移位）、轻度组（关节盘轻度前移位）、中度组（关节盘中度前移位）和重度组（关节盘重度前移位）。然后利用Mimics 20软件基于CBCT数据进行TMJ的相关形态学参数测量，包括髁突线性尺寸（宽度、长度和高度）、髁突体积和表面积，关节窝的深度和长度，关节结节倾斜角，关节前、上、后间隙等，并对各组矢状髁突位置进行评估。使用方差分析、非参数检验和卡方检验等比较关节形态及位置参数的组间差异，采用相关性分析探索矢状关节盘位置与关节测量参数之间的相关性。结果　髁突的线性尺寸、关节窝深度、关节倾斜角、关节间隙和矢状髁突位置分布在4组间差异有统计学意义，而关节窝长度在4组间差异没有统计学意义；相关性分析显示：髁突的线性尺寸、髁突的体积及表面积、关节窝的深度、关节结节倾斜角和关节上间隙与关节盘矢状位置之间存在显著负相关，而关节后间隙与矢状关节盘位置之间存在显著正相关。结论　TMJ骨形态与不同矢状关节盘位置之间存在相关性，应警惕临床看到的关节骨形态的退行性改变可能是患者存在关节盘前移位的标志。     

牙颌专用CT对颞下颌关节骨性结构的测量技术

目的：探讨牙颌专用CT对颞下颌关节（temporomandibular joint，TMJ）骨性结构的测量技术。方法：在牙颌专用CT对TMJ成像技术的基础上，对TMJ成像的轴位、矢状位、平行于髁状突长轴的斜位、垂直于髁状突长轴的斜位重建影像，建立座标点并进行测量。结果：轴位测得髁状突水平角和单侧髁状突与矢状中线的半径距离。平行于髁状突长轴的斜位测得髁状突长轴径值、髁状突垂直角、关节间隙和髁状突受力角。垂直于髁状突长轴的斜位与矢状位均可测得髁状突内外极间各层切面径值、关节间隙、关节凹深度、关节结节斜度和髁颈厚度。结论：牙颌专用CT成像系统可以对TMJ骨性结构行多种体位、角度的影像重建及定点测量。