基于锥形束CT分析骨性Ⅲ类高角伴下颌偏斜患者髁突形态和位置的研究

目的 应用锥形束CT（CBCT）对比分析骨性Ⅲ类高角伴下颌偏斜患者与个别正常牙合患者髁突的形态和位置。方法 选取2017年9月至2019年9月于上海交通大学医学院附属第九人民医院口腔正畸科就诊的患者40例，其中骨性Ⅲ类高角伴下颌偏斜患者20例（偏斜组），个别正常牙合患者20例（对照组）。所有患者于治疗前拍摄CBCT，使用Invivo 5.0软件对CBCT影像进行三维重建及测量，并比较两组患者两侧髁突形态和位置的差异。结果 （1）偏斜组患者两侧髁突形态和位置指标测量值比较发现，在髁突形态方面，偏斜侧髁突最大轴面面积、髁突高度、髁顶高度均比非偏斜侧小，差异均有统计学意义（均P < 0.05）。在髁突位置方面，偏斜侧髁突外间隙、上间隙和后间隙比非偏斜侧小；偏斜侧髁突前间隙、内间隙及髁突外突距比非偏斜侧大，差异均有统计学意义（均P < 0.05）。（2）对照组两侧髁突形态和位置指标测量值比较，差异均无统计学意义（均P > 0.05）。（3）偏斜组两侧髁突形态和位置指标测量值分别与对照组比较发现，在髁突形态方面，偏斜组偏斜侧髁突高度比对照组大，最大轴面面积比对照组小；非偏斜侧髁突高度大于对照组，差异均有统计学意义（均P < 0.05）。在髁突位置方面，偏斜组偏斜侧髁突上间隙小于对照组，髁突内间隙、前间隙、髁突外突距及髁突与正中矢状面距大于对照组，差异均有统计学意义（均P < 0.05）。结论 骨性Ⅲ类高角伴下颌偏斜患者双侧髁突的形态和位置具有明显的不对称性，偏斜侧髁突形态较对侧小，并向后上外方向移位。骨性Ⅲ类高角伴下颌偏斜患者的髁突高度比个别正常牙合患者大。     

Postoperative stability of bimaxillary surgery in Class III patients with mandibular protrusion and mandibular deviation: a frontal cephalometric study

The aims of this study into bimaxillary surgery were to investigate and compare the postoperative stability of deviated side (lengthened side) and non-deviated side (shortened side), the effect of the type of surgery performed in the mandible, and the changes in signs and symptoms of temporomandibular joint (TMJ) disorders before and after surgery. The sample consisted of 31 Class III patients in whom imbalance between the maxilla and the mandible were corrected by Le Fort I osteotomy combined with bilateral intraoral vertical ramus osteotomy (BIVRO group, n=9), bilateral sagittal split ramus osteotomy (BSSRO group, n=10), or IVRO and SSRO (IVRO+SSRO group, n=12). IVRO+SSRO and BIVRO are more effective in improving TMJ signs and symptoms. There was no significant post-surgical difference between deviated and non-deviated sides in any group. BIVRO and BSSRO showed excellent post-surgical stability on both sides; less was found in the IVRO+SSRO group. The IVRO+SSRO group showed greater transverse displacement in menton point than the BIVRO group. In conclusion, after bimaxillary surgery and in asymmetric patients there were no differences between deviated and non-deviated sides, BIVRO and BSSRO appear to be more stable than IVRO+SSRO.     

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...     

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Abstract

The present study was undertaken to investigate the correlation between condylar position, articular eminence morphology, and mandibular deviation using helical CT in a group of 22 female subjects (mean age 19.2±5.3 years) with mandibular deviation. There was a significant difference in the angles of the posterior-slope of the articular eminence (PSA) between the deviated (44.27±10.29°) and non-deviated (42.50±9.90°) sides. Mandibular deviation also correlated significantly with both medial joint space (r=0.581) and the PSA (r=0.653). A significant negative correlation was also found between mandibular deviation and the anterior/posterior joint space ratio (r=-0.450). These results demonstrated that patients with mandibular deviation possibly show asymmetries not only in their glenoid fossa morphology but also in their condylar position.     

Changes in temporomandibular joint and ramus after sagittal split ramus osteotomy in mandibular prognathism patients with and without asymmetry

The purpose of this study was to examine the changes in the temporomandibular joint (TMJ) and ramus after sagittal split ramus osteotomy (SSRO) with and without Le Fort I osteotomy.The subjects consisted of 87 Japanese patients diagnosed with mandibular prognathism with and without asymmetry. They were divided into 2 groups (42 symmetric patients and 45 asymmetric patients). The TMJ disc tissue was assessed by magnetic resonance imaging (MRI) and the TMJ space, condylar and ramus angle were assessed by computed tomography (CT) preoperatively and postoperatively.Medial joint space on the deviation side in the asymmetry group was significantly larger than that in the symmetry group (P = 0.0043), and coronal ramus angle on the non-deviation side in the asymmetry group was significantly larger than that in the symmetry group preoperatively (P = 0.0240). The horizontal condylar angle on the deviation side in the asymmetry group was significantly larger than that in the symmetry group (P = 0.0302), posterior joint space on the non-deviation side in the symmetry group was significantly larger than that in the asymmetry group postoperatively (P = 0.00391).The postoperative anterior joint space was significantly larger than the preoperative value on both sides in both groups (the deviation side in the symmetry group: P = 0.0016, the non-deviation side in the symmetry group: P < 0.0001, the deviation side in the asymmetry group: P = 0.0040, the non-deviation side in the asymmetry group: P = 0.0024). The preoperative disc position could was not changed in either group.These results suggest that significant expansion of anterior joint space could occur on the deviation side and non-deviation side in the asymmetry group as well as on both sides in the symmetry group, although disc position did not change in either group.     

Relations between anterior disc displacement and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle

In this study we investigated the relation between anterior disc displacement (ADD) and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle. Thirty female patients (60 joints) with both conditions were evaluated. Magnetic resonance imaging of the temporomandibular joint (TMJ) was used to diagnose both ADD and changes to the mandibular condyle (erosion, osteophyte, and deformity). The relations among ADD, changes to the mandibular condyle, and maxillomandibular morphology were examined statistically. Changes to the mandibular condyle had a higher score than sym anterior open bite, the deviated side in asymmetric anterior open bite, and the non-deviated side. The score for disc displacement on the non-deviated side was lower than both the sym side and the deviated side. Unilateral changes to the mandibular condyle and unilateral disc displacement were not apparent in sym anterior open bite, but a unilateral non-displaced disc was seen only on the asymmetric side. Mandibular condylar changes were significantly more common on the deviated, than on the non-deviated, side. The SNB angle was significantly smaller, and the ANB, GZN, and SN-mandibular plane angles were significantly larger in sym anterior open bite. Overjet, ANB angle, GZN angle, and SN-MP angle were significantly larger, and the SNB angle was significantly smaller, in the presence of ADD without reduction and mandibular condylar deformity. We conclude that the prevalence of ADD without reduction and changes to the mandibular condyle were related to mandibular asymmetry and mandibular morphology in anterior open bite. This retrospective study suggests that ADD without reduction and mandibular condylar bone changes may be related to the progression of skeletal class II open bite and mandibular asymmetry in cases of skeletal open bite.     

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。     

Relationship between occlusal curvatures and mandibular deviation in orthodontic patients with temporomandibular disorders

The aim of this study was to investigate the relationships between occlusal curvature (OC) and frontal craniofacial morphology in patients with and without temporomandibular disorders (TMD), using frontal cephalograms and a sophisticated measuring device (XYZAX S400A). Thirty-seven female orthodontic patients (mean age 24.0 years) were divided into a TMD group (n = 25) and no-TMD group (n = 12). In the TMD group, the lateral OCs of the mandibular second premolar, and first and second molars were significantly deeper on the deviated side than on the non-deviated side, and the anteroposterior OCs of the mandibular second premolar and first molar were also significantly shallower on the deviated side. In the no-TMD group, however, there were no significant differences in OCs between deviated and non-deviated sides. The differences between right and left lateral OCs in the mandibular second premolar and first and second molars, as well as the anteroposterior OCs in the mandibular first and second molars, showed significant correlations with mandibular deviation in the TMD group. On the other hand, in the no-TMD group, there was no significant correlation between OCs and mandibular deviation. The above results suggest that OCs might try to compensate for mandibular deviation in patients with TMD.     

Temporomandibular joint morphology and disc position in skeletal class III patients

INTRODUCTION: The purpose of this study was to investigate the relationship between temporomandibular joint (TMJ) morphology, including discal tissue and clinical symptoms in class III dentofacial deformity patients. MATERIAL AND METHODS: Forty-four patients were examined with lateral, frontal and axial cephalograms. They were divided into two groups, consisting of a class III symmetry and a class III asymmetry group. By using magnetic resonance imaging the 88 joints could be classified into four types on the basis of disc position and shape: anteriorly displaced disc, anterior type, fully-covered type and posterior type. Furthermore, TMJ morphology was measured tomographically in the sagittal plane. RESULTS: Anteriorly displaced discs in the asymmetry group (56.8%) occurred significantly more frequently than in the symmetry group (18.2%; p <0.05). TMJ symptoms (clicking, crepitus, closed lock, pain) were seen in 17/44 joints (38.6%) of the symmetry and 24/44 joints (54.5%) of the asymmetry group, for a total of 41/88 joints (46.6%). There were no differences in joint space ratio and condyle ratio. However, the fossa ratio on the deviation side was significantly higher than on the nondeviation side in the asymmetry group (p<0.05). CONCLUSION: The incidence of internal derangement in asymmetrical class III patients is higher than in symmetrical mandibular prognathism, and this difference is associated with a difference in TMJ morphology of both sides.     

Temporomandibular joint symptoms and disc displacement in patients with mandibular prognathism

Our objective was to find out the incidence of signs and symptoms of temporomandibular joint (TMJ) and disc displacement in patients with mandibular prognathism. Fifty-one patients were examined clinically and by axial computed tomography(CT). The incidence of TMJ signs and symptoms was 6/25(24%) in patients with simple mandibular prognathism and 12/26(46%) in patients with mandibular prognathism and asymmetry. No discs were displaced in patients with simple mandibular prognathism, but 15(58%) of the patients with mandibular prognathism and asymmetry had displaced discs. There was no association between signs and symptoms of TMJ and disc displacement. Patients with mild protrusion and severe asymmetry of the mandible had a high incidence of disc displacement, which interestingly was on the deviated side in 14 of the 15 patients affected. We conclude that skeletal morphology may have a role in the development of TMJ disorders but the mechanism is obscure.     

成人与儿童颞下颌关节骨性形态比较研究

目的:比较成人与儿童颞下颌关节(temporomandibular joint,TMJ)骨性形态的差异。方法:用多排螺旋 CT(multislice CT,MSCT)对30例健康成年志愿者和20具咬合关系正常的儿童尸体 TMJ 扫描,结合影像中心保存的10例正常儿童 TMJ 的 MSCT 资料,在工作站上对上述60例120侧 TMJ 的 MSCT 图像进行多平面重建和参数测量,SPSS 软件对反映 TMJ 骨性形态特征的参数或其比值作统计学分析。结果:髁突纵轴倾斜角、髁突颈最小/髁突头最大横断面积、髁突前后径/关节窝前后径、髁突内外径/关节窝内外径、髁突在关节窝中后间隙/前间隙、关节窝前斜面倾角、关节窝深度、关节结节倾角,成人和儿童差异有显著性(P<0.05)。结论:成人与儿童 TMJ 骨性形态存在部分差异,它对 TMJ 疾病的防治有指导意义。     

An animal model for inducing anterior disc displacement of the temporomandibular joint

AIMS: To develop an animal model of anterior disc displacement (ADD) without the need for opening the temporomandibular joint (TMI) capsule. METHODS: Thirty-two healthy adult Japanese white rabbits were used in this study. Four rabbits were dissected to familiarize the investigators with the anatomy of the TMJ. Sixteen animals were subjected to surgical ADD in the right TMJ, 8 animals had a sham operation, and 4 animals were not operated (normal controls). Four rabbits from the experimental ADD group and 2 from the sham group were sacrificed 1, 2, 4, and 8 weeks, respectively. The rabbits in normal control group were sacrificed at the beginning of the experiment. Animal behaviors as well as macro- and microchanges in the TMJs were investigated. RESULTS: Fifteen right TMJ discs in the 16 experimental rabbits were successfully displaced anteriorly, and the degree of ADD in the experimental group was similar. The mandible of each ADD rabbit deviated to the left side with inclined attrition of the incisors. Some histologic changes appeared in the experimental TMJs. CONCLUSION: This ADD technique without the need for opening the TMJ capsule is effective, and the model is suitable for studying ADD of the TMJ.     

Craniofacial asymmetry and temporomandibular joint internal derangement in female adolescents: a posteroanterior cephalometric study

Unilateral or bilateral pathology of the osseous components of the temporomandibular joint (TMJ) can result in pronounced facial asymmetry because of dissimilar size and shape of the right and left sides of the mandible. To date, it is unknown whether abnormalities of the soft tissues of the TMJ are associated with greater than normal craniofacial asymmetry. In this study, we investigated the amount of craniofacial asymmetry in female orthodontic patients with unilateral or bilateral TMJ internal derangement (TMJ ID) relative to the amount in female patients without TMJ ID. The total sample consisted of 80 female adolescents. Bilateral TMJ magnetic resonance images were used as a database for objectively scoring the severity of TMJ ID. Craniofacial asymmetry was measured from posteroanterior cephalograms. Females with bilateral TMJ ID had significantly greater asymmetry in the vertical position of the antegonion. If the TMJ ID was more advanced on the right side, the ipsilateral ramus was shorter, resulting in significant asymmetry in this region. In all other craniofacial regions, the amount of asymmetry was not significant between females with normal TMJs and those with TMJ ID. The results indicate that a female orthodontic patient with bilateral TMJ ID or unilateral right TMJ ID may present with or develop a vertical mandibular discrepancy.     

The effects of changing position and angle of the proximal segment after intraoral vertical ramus osteotomy

The authors evaluated changes in position and angle of the proximal segment, including the condyle, after intraoral vertical ramus osteotomy (IVRO) with and without a Le Fort I osteotomy to verify whether displacement of the proximal segment could induce postoperative complications. Changes in condylar angle, ramus angle, and displacement of proximal segment were measured pre- and postoperatively. The position of the temporomandibular joint (TMJ) disc was examined pre- and postoperatively. Trigeminal nerve hypoesthesia in the lower lip was assessed bilaterally. The postoperative horizontal condylar angle was significantly smaller than the preoperative one on the deviated and non-deviated sides (P<0.0001). The postoperative coronal condylar angle was significantly larger than the preoperative one on the deviated side (P=0.0483). The postoperative sagittal ramus angle was larger than the preoperative one on the deviated (P<0.0001) and non-deviated (P=0.00005) side. Most joints with an anteriorly-displaced disc with and without reduction improved on the non-deviated side; 5 of 16 joints improved on the deviated side. Results suggest the position and angle of the proximal segment, including the condyle, could change after IVRO. This could be associated with symptomatic improvement in TMJ, and extreme medial displacement of the proximal segment could delay recovery from lower lip hypoesthesia.     

Morphological study of the changes after sagittal split ramus osteotomy in patients with facial asymmetry: measurements of 3-dimensional modelling

The effects of bilateral sagittal split ramus osteotomy (BSSRO) on the temporomandibular joint (TMJ) are still not well understood. The aim of this study was to compare the morphological differences among unaffected subjects on the one hand, and patients with facial asymmetry before and after BSSRO on the other. Ten Chinese patients (preoperative and postoperative groups, mean (SD) age 25 (5) years) diagnosed with facial asymmetry and 10 unaffected subjects (control group, mean (SD) age 27 (5) years) were recruited prospectively. The 3-dimensional morphological measurements made on 3-dimensional models in each group were assessed by analysis-of-variance (ANOVA) and Student’s t test, and probabilities of <0.05 were accepted as significant. The horizontal condylar angle (HCA), coronal condylar angle (CCA), sagittal ramus angle (SRA), medial joint space (MJS), lateral joint space (LJS), and superior joint space (SJS) differed significantly between the preoperative and control groups (HCA: p = 0.000, CCA: p = 0.000, SRA(left/undeviated side): p = 0.002, MJS(left/undeviated side): p = 0.000, MJS(right/deviated side): p = 0.007, LJS(right/deviated side): p = 0.000, SJS(left/undeviated side): p = 0.000, SJS(right/deviated side): p = 0.000). The SRA, MJS, LJS, and SJS differed significantly between the preoperative and postoperative groups (SRA(left/undeviated side): p = 0.012, MJS(left/undeviated side): p = 0.002, LJS(right/deviated side): p = 0.021, SJS(left/undeviated side): p = 0.000, SJS(right/deviated side): p = 0.001), And the SRA, MJS, and LJS in the preoperative group differed significantly between the deviated and undeviated side (SRA: p = 0.006; MJS: p = 0.003; LJS: p = 0.011). However, there were no significant differences in the postoperative and control groups between the deviated and undeviated sides. BSSRO improved the asymmetrical morphology of the TMJ and alleviated the symptoms.     

Facial asymmetry in subjects with skeletal Class III deformity

We investigated the frequency, site, amount, and direction of facial asymmetry in human adults with mandibular prognathism and examined if these characteristics were associated postnatally with cardinal clinical signs that may indicate a predisposition to facial asymmetry. Two hundred twenty young Japanese adults (69 men and 151 women) who exhibited skeletal Class III malocclusions were selected. The sample was divided into a Postnatal Factor Group and a Nonpostnatal Factor Group. The former group included those who had: (1) received orthodontic treatment using a chin cap; (2) exhibited clinical symptoms of temporomandibular joint (TMJ) disorder; (3) reported a history of maxillofacial trauma; or (4) radiographic abnormality of the condyles. Subjects with a deviation of more than 2 mm from the facial midline associated with any of the 4 landmarks (ANS, U1, L1 and Me) were classified as asymmetric and the asymmetry was measured on a postero-anterior (P-A) cephalogram. Radiographic facial asymmetry was found frequently (70%-85%, for Menton), and most obviously in the lower jaw (P < .05). Lateral displacement toward the left side of the face occurred more often than right-sided deviation (P < .001, for Menton). However, the Postnatal Factor Group showed a higher proportion of subjects with lateral deviation toward the right side (P = .0031) and a greater amount (P < .0001) of chin deviation. This was due to the fact that the subjects having TMJ problems as a postnatal factor showed no directional uniqueness in jaw deviation and exhibited a longer distance of deviation.     

上颌四眼簧扩弓纠正早期功能性下颌偏斜的髁突位置变化研究

目的:通过颞下颌关节断层片测量,探讨上颌四眼簧扩弓纠正单侧后牙反(牙合),改善早期功能性下颌偏斜后髁突位置的变化.方法:混合牙列或早期恒牙列,单侧后牙反(牙合)伴有或不伴有前牙反(牙合),下颌功能性偏斜患者16例,采用上颌Quad-Helix扩弓法,对矫治前后颞下颌关节断层片进行测量分析.结果:单侧后牙反(牙合)矫正后,偏斜侧T1期与T2期髁突位置变化无统计学意义(P＞0.05).对侧髁突向后移动,即治疗后,对侧关节腔前间隙增大,上间隙和后间隙比治疗前减小(p＜0.05).结论:混合牙列或早期恒牙列,上颌四眼簧扩弓器纠正单侧后牙反(牙合),使髁突与关节窝关系发生改变,两侧髁突运动逐渐对称.     

阻塞性睡眠呼吸暂停低通气综合征患者颞下颌关节间隙测量

目的:通过对阻塞性睡眠呼吸暂停低通气综合征(obstructive sleep apnea hypopnea syndrome,OSAHS)患者的颞下颌关节(temporomandibular joint,TMJ)行磁共振扫描分析,探讨OSAHS患者与正常人群颞下颌关节形态的差异.方法:选取2014年1月-2016年5月收治的18例OSAHS患者和18例健康成人,分别记为研究组和对照组;按照呼吸暂停及低通气指数(apnea and hypopnea index,AHI),将OSAHS患者分为轻、中、重3个亚组(n=6).对所有纳入人群行TMJ的MRI扫描并测量关节间隙,采用SPSS 17.0软件包对测量数据进行统计学处理.结果:2组患者在年龄、性别构成、关节上间隙及髁突有无移位方面差异均无显著性(P＞0.05).OSAHS患者TMJ左侧前间隙[(2.61±0.19)mm:(2.47±0.18)mm,P＜0.05]、右侧前间隙[(2.63±0.18)mm:(2.48±0.17)mm,P＜0.0S]大于正常人群.OSAHS患者TMJ左侧后间隙[(2.43±0.20)mm:(2.51±0.19)mm,P＜0.05]、右侧后间隙[(2.44±0.20)mm:(2.60±0.13)mm,P＜0.05]小于正常人群.轻度OSAHS组TMJ左侧前间隙[(2.53±0.26)mm:(2.73±0.07) mm,P＜0.05]、右侧前间隙[(2.54±0.11)mm:(2.74±0.14)mm,P＜0.05]均小于重度组;轻度OSAHS组TMJ左侧后间隙[(2.56±0.29)mm:(2.29±0.09)mm,P＜0.05]、右侧后间隙[(2.55±0.23) mm:(2.31±0.09)mm,P＜0.05]均大于重度组.结论:OSAHS患者的髁突相比正常人群处于关节窝偏后位置.髁突位于关节窝偏后位置的趋势与OSAHS的严重程度相关.     

Transitional joint effusion in the mandibular prognathic surgery patient: intraoral vertical ramus osteotomy versus sagittal split ramus osteotomy.

PURPOSE: The purpose of this study was to examine the cause of joint effusion (JE) appearing postoperatively in the temporomandibular joint (TMJ) of patients with mandibular prognathism on T2-weighted magnetic resonance (MR) images. PATIENTS AND METHODS: MR imaging was performed before and after surgery in 30 TMJs of 15 subjects with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) and in 20 TMJs of 10 subjects with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO). The preoperative MR imaging was performed 1 month before surgery, and postoperative MR imaging was performed during maxillomandibular fixation. RESULTS: Preoperatively, none of SSRO and IVRO groups had JE. Postoperatively, 12 TMJs (40%) of the IVRO group and only 1 TMJ (5%) of the SSRO group had JE. As for the TMJs in the IVRO group, on MR imaging, the degree of downward movement of the condyle after surgery was larger in TMJs with JE (3.8 +/- 2.3 mm) than in TMJs without JE (1.8 +/- 1.6 mm). JE diminished within about 4 months after removal of the maxillomandibular fixation. CONCLUSION: JE appearing postoperatively in the TMJ of patients with mandibular prognathism might be relation to the degree of downward movement of the condyle.     

Condylar changes after contralateral mandibular osteotomy in the rabbit

Following orthognathic surgery undesirable changes in the temporomandibular joints (TMJs) are noted sometimes. Altered stress on the condyle and surrounding tissue frequently causes morphological changes in the TMJ. The purpose of the present study was to assess these morphologic changes in a rabbit following mandibular osteotomy and the resulting mandibular body rotation. Adult male Japanese white rabbits (3 kg, 12-16 weeks old) were applied in this study. An experimental mandibular osteotomy was performed on the right side of the body of the mandible. The surgery includes vertical mandibular body osteotomy 5 mm in width after masseter muscle reflection. Then the anterior and posterior osseous segments were fixed with wire at previously made holes. As a result, the condylar medio-lateral width on the contralateral (left) side was significantly larger than that of the ipsilateral side 2 weeks postoperatively (p < 0.05). There were significant differences in the angle between the right and the left condylar heads 4 weeks postoperatively (p < 0.05). The present experimental study demonstrated morphological changes in the contralateral TMJ caused by unilateral mandibular osteotomy. Postoperative morphological changes implied that there is a process of biological adaptation in the rabbit TMJ.