Auriculo-condylar syndrome: further evidence for a new disorder.

We report on a patient born to normal and nonconsanguineous parents and presenting with strikingly malformed ears, abnormalities of the condyle of the mandible, micrognathia, small mouth, and cleft uvula. The similarity of our patient with those reported previously by Jampol et al. [1998: Am. J. Med. Genet. 75:449-452] led us to suggest that they have the same condition.     

Prenatal development of the human mandible.

In an effort to better understand the interrelationship of the growth and development pattern of the mandible and condyle, a sequential growth pattern of human mandibles in 38 embryos and 111 fetuses were examined by serial histological sections and soft X-ray views. The basic growth pattern of the mandibular body and condyle appeared in week 7 of fertilization. Histologically, the embryonal mandible originated from primary intramembranous ossification in the fibrous mesenchymal tissue around the Meckel cartilage. From this initial ossification, the ramifying trabecular bones developed forward, backward and upward, to form the symphysis, mandibular body, and coronoid process, respectively. We named this initial ossification site of embryonal mandible as the mandibular primary growth center (MdPGC). During week 8 of fertilization, the trabecular bone of the mandibular body grew rapidly to form muscular attachments to the masseter, temporalis, and pterygoid muscles. The mandible was then rapidly separated from the Meckel cartilage and formed a condyle blastema at the posterior end of linear mandibular trabeculae. The condyle blastema, attached to the upper part of pterygoid muscle, grew backward and upward and concurrent endochondral ossification resulted in the formation of the condyle. From week 14 of fertilization, the growth of conical structure of condyle became apparent on histological and radiological examinations. The mandibular body showed a conspicuous radiating trabecular growth pattern centered at the MdPGC, located around the apical area of deciduous first molar. The condyle growth showed characteristic conical structure and abundant hematopoietic tissue in the marrow. The growth of the proximal end of condyle was also approximated to the MdPGC on radiograms. Taken together, we hypothesized that the MdPGC has an important morphogenetic affect for the development of the human mandible, providing a growth center for the trabecular bone of mandibular body and also indicating the initial growth of endochondral ossification of the condyle.     

Prenatal development of the human mandible

In an effort to better understand the interrelationship of the growth and development pattern of the mandible and condyle, a sequential growth pattern of human mandibles in 38 embryos and 111 fetuses were examined by serial histological sections and soft X‐ray views. The basic growth pattern of the mandibular body and condyle appeared in week 7 of fertilization. Histologically, the embryonal mandible originated from primary intramembranous ossification in the fibrous mesenchymal tissue around the Meckel cartilage. From this initial ossification, the ramifying trabecular bones developed forward, backward and upward, to form the symphysis, mandibular body, and coronoid process, respectively. We named this initial ossification site of embryonal mandible as the mandibular primary growth center (MdPGC). During week 8 of fertilization, the trabecular bone of the mandibular body grew rapidly to form muscular attachments to the masseter, temporalis, and pterygoid muscles. The mandible was then rapidly separated from the Meckel cartilage and formed a condyle blastema at the posterior end of linear mandibular trabeculae. The condyle blastema, attached to the upper part of pterygoid muscle, grew backward and upward and concurrent endochondral ossification resulted in the formation of the condyle. From week 14 of fertilization, the growth of conical structure of condyle became apparent on histological and radiological examinations. The mandibular body showed a conspicuous radiating trabecular growth pattern centered at the MdPGC, located around the apical area of deciduous first molar. The condyle growth showed characteristic conical structure and abundant hematopoietic tissue in the marrow. The growth of the proximal end of condyle was also approximated to the MdPGC on radiograms. Taken together, we hypothesized that the MdPGC has an important morphogenetic affect for the development of the human mandible, providing a growth center for the trabecular bone of mandibular body and also indicating the initial growth of endochondral ossification of the condyle. Anat Rec 263:314–325, 2001. © 2001 Wiley‐Liss, Inc.     

Regional differences in architecture and mineralization of developing mandibular bone

The goal of this study was to investigate the mutual relationship between architecture and mineralization during early development of the pig mandible. These factors are considered to define the balance between the requirements for bone growth on the one hand and for load bearing on the other. Architecture and mineralization were examined using micro-CT, whereas the mineral composition was assessed spectrophotometrically in groups of fetal and newborn pigs. The development of the condyle coincided with a reorganization of bone elements without an increase in bone volume fraction, but with an increase in mineralization and a change in mineral composition. In the corpus, the bone volume fraction and mineralization increased simultaneously with a restructuring of the bone elements and a change in mineral composition. The growth of the condyle was reflected by regional differences in architecture and mineralization. The anterior and inferior regions were characterized by a more dense bone structure and a higher mineralization as compared to posterior and superior regions, respectively. In the corpus, growth was mainly indicated by differences between buccal and lingual plates as well as between anterior, middle, and posterior regions characterized by a more compact structure and higher mineralization in the lingual and middle regions. In conclusion, the architecture and mineralization in the condyle and corpus started to deviate early during development toward their destiny as trabecular and cortical bone, respectively. These results were compatible with those obtained with mineral composition analysis. Regional differences within condyle and corpus reflected known developmental growth directions.     

下颌骨缺损个体化修复体的应力分析与优化设计

背景：采用钛网支架整复下颌骨缺损常因设计不合理、固定不当造成修复体松脱甚至折断导致失败。 目的：针对一侧髁状突的下颌骨缺损,探讨使下颌骨断端和修复体应力分布合理的最佳设计方案和固定方式。 方法：建立下颌骨断端的简易三维模型和三种修复体模型,模拟咀嚼运动,施加垂直方向载荷,进行有限元法应力分析。 结果与结论：3种设计方案中,延伸板形态与下颌骨外形一致并包绕下颌骨下缘,并在下颌骨下缘增加固定螺钉的设计,在负荷时修复体变形最小,下颌骨断端及固定螺钉受力也最小。提示在单端固定式下颌骨修复体的设计中,应将延伸板形态设计为与下颌骨外形一致且包绕下颌骨下缘,并有必要增加下颌骨下缘处的固定。     

Remarks on the morphology of the human temporomandibular joint in the fetal period

Skeletons of human fetuses of different ages allow the study of the considerable transformations of the mandibular joint and the mandible in this relative short stage of life. The condyle is anchored in the mandible by a conical process. The tip of this cone extends to the anLage of the 2nd milk molar. The conical process can be recognized macroscopically up to newborn age. It can also be identified by modern imaging methods. The cone can be well distinguished from the surrounding bone of the mandible. The mandibular joints of fetuses in the 31st, the 32nd, the 39th week and of a newborn were dissected, removed, and histologically investigated. The conical process of the condyle was clearly observed. The cartilage on the condyle is characterised by a layered structure which is typical for a center of growth. In the cartilage of young fetuses, blood vessels were found, reaching from the trabecular bone to the articular space. At this stage of life, blood vessels are also present in the central part of the discus articularis.     

Magnetic resonance imaging findings of true bifid mandibular condyle with duplicated mandibular fossa

Bifid mandibular condyle (BMC) is a rare asymptomatic morphological alteration with no predilection for age group or gender. Its morphology varies from a shallow groove to two condylar heads with separate necks, oriented mediolaterally or anteroposteriorly. This report describes an unusual case of anteroposterior bifid condyle in a 39-year-old female patient with the main complaint of mouth-opening limitation and a deviation of the mandible to the left side. Magnetic resonance imaging (MRI) findings revealed a bifid condyle on the left side and duplicated mandibular fossa, with the articular disc over the anterior head. The MRI images in the open-mouth position revealed minimal movement of the condyle. Despite the increased number of mediolateral bifid mandibular condyle cases described in the literature, none of previously reported cases of BMC included an anteroposterior bifid condyle case with two distinct mandibular fossa.     

有限元分析犬下颌不全截骨牵张时特定标志点位移情况

目的：利用犬不完全截骨牵张成骨的有限元模型观察牵张过程中下颌骨特定点位移情况。方法：有限元模型模拟不完全截骨（截骨处剩lmm舌侧皮质骨），观察下颌骨一些特定标志点在牵张过程中空间三维的位移趋势。结果：在牵张过程中牵张侧下颌骨标志点位移趋势为在内外（左右或x轴）方向上第五臼齿、喙突、髁状突前斜面前缘中点的运动趋势是向外的，而下颌角、髁状突后斜面后缘中点的运动趋势是向内的；在前后（y轴）方向上第五臼齿、喙突的运动趋势是向后的，而下颌角的运动趋势是向前的；在上下（z轴）方向上第五臼齿的运动趋势是向上的。结论：牵张侧下颌骨在矢状平面上有使下颌骨体前端拉高后端压低的倾向，在冠状平面上有使下颌骨体上缘外翻下缘内收的倾向。     

咬合接触对颞下颌关节生物力学影响的有限元研究

目的建立用于研究咬合接触与颞下颌关节生物力学关系的三维有限元模型,并设计不同的工况来分析不同咬合接触情况下颞下颌关节应力的变化规律。方法尸体头颅1具,平行于眶耳平面作CT扫描;取石膏模型,以三维扫描仪对牙列(牙合)面扫描;将石膏模型扫描参数与CT扫描参数换算到同一坐标系下,在髁突上方设均厚的类关节盘,关节盘顶及下颌角作约束设计,经划分网格生成有限元模型。工况一:左侧下颌不同牙位咬合接触面加载;工况二:在包括左侧下颌第二磨牙的颞下颌关节三维有限元模型上,设计下颌第二磨牙牙尖交错(牙合)、远中方向和颊侧方向三种加载部位的工况,研究不同工况下双侧髁突处应力分布变化的规律。结果(1)建立了包括双侧髁突、类关节盘及下颌牙列在内的用于分析咬合与颞下颌关节关系的三维有限元模型。(2)咬合加载牙位不同,双侧髁突应力效应不同,髁突外、中、前、顶等处为承受较高压强的区域。(3)咬合加载部位牙面承载形态不同,双侧髁突应力效应也不同,其变化包括应力性质和应力的分布特点等方面,远中加载和颊侧加载时分别可致加载侧髁突内极和加载对侧髁突内极应力集中。结论咬合接触部位及方向变化可影响髁突应力分布。     

Simpson-Golabi-Behmel syndrome associated with renal dysplasia and embryonal tumor: localization of the gene to Xqcen-q21.

We report 6 affected males in a 5-generation family with x-linked Simpson-Golabi-Behmel (SGB) syndrome. All had pre- and postnatal overgrowth with 2 adult males attaining heights over 195 cm. Other features included "coarse" face with hypertelorism, broad nasal root, cleft palate, full lips with a midline groove of the lower lip, grooved tongue with tongue tie, prominent mandible, congenital heart defects, arrhythmias, supernumerary nipples, splenomegaly, large dysplastic kidneys, cryptorchidism, hypospadias, skeletal abnormalities and postaxial hexadactyly. All affected individuals were of normal intelligence. One boy died at age 19 months of a neuroblastoma. The putative origin of the gene in this family was the maternal great grandmother of the propositus. Eight carrier females, who showed varying manifestations of the gene, have been identified. Anthropometric analysis has identified preliminary characteristic craniofacial dimensions in this syndrome. Molecular studies have shown a maximal lod score of 2.81 with no recombinants observed for the SGB-DXYS68 pairing, mapping the disorder to Xqcen-Xq21.3.     

熔融沉积成型和选择性激光烧结打印聚醚醚酮髁突假体的生物力学研究

目的 对3D打印个性化聚醚醚酮(poly-ether-ether-ketone,PEEK)髁突假体进行有限元分析和压缩性能测试,分析假体的应力分布特征及机械力学性能,评估假体的临床应用价值及应用前景.方法 通过CBCT、Mimics、Geomagic Studio、Solid Works和ANSYS Workbench...     

广东地区人群颞下颌关节解剖参数的三维分析

目的 对广东地区不同人群的下颌骨及髁突解剖参数进行三维分析。 方法 选取就诊于南方医科大学口腔医院的患者265名,利用CBCT分别测量男性和女性的髁突长度、髁突高度、下颌升支高度、下颌体高度以及下颌神经进入下颌升支的位置。 结果 所有患者髁突的平均长度（内极-外极）二维测量为19.2 mm、三维测量为20.3 mm,男性比女性长3.6 mm,两者之间无统计学差异。下颌骨高度、髁突高度和下颌升支高度分别为59.6 mm,22.8 mm和38.3 mm,其中下颌骨高度男性比女性长6.4 mm,两性之间有统计学差异。下颌升支的宽度、下颌小舌到升支前缘的距离和下颌小舌到升支后缘的距离分别为：29.4 mm,14.8 mm及14.6 mm,男女之间均无统计学差异。 结论 CBCT测量颞下颌关节有着更显著的准确性,本实验结果丰富了中国人群下颌骨解剖数据,有助于开发适合广东地区的人工颞下颌关节。 【关键词】 下颌骨; 髁突; CBCT; 人工颞下颌关节     

股骨头及股骨体测量统计分析

目的 研究股骨头与股骨体大小的关系。方法 对70块股骨的头与体的部分指数进行测量及统计学分析。结果 股骨头垂直径、矢状径及周径与股骨转子内髁长、股骨转子外髁长及股骨中部横径有相关关系。结论 可通过测量股骨转子内髁长、股骨转子外髁长及股骨中部横径来估算股骨头垂直径、矢状径及周径。     

Anatomical abnormalities in mandibulofacial dysostosis

A detailed dissection of the head and neck of a 7-month-old boy with mandibulofacial dysostosis is described and compared with other reported cases. A general growth retardation was found in the bones of the basicranium and calvaria as well as the face. The base of the skull was kyphotic, and the elements derived from the branchial arches articulated with the basicranium more anteriorly than usual. Certain middle ear structures were found to be extracranial. The facial muscles were generally normal except for the absence of elevators of the upper lip. The laryngeal cartilages were shortened anteroposteriorly, resulting in drastic reduction of the rima glottidis. The attachments of the masticatory muscles to the mandible suggested that the area of the temporomandibular joint had not completed normal differentiation, and that that part of the mandible which functioned as a condyle was actually an ossification around Meckel's cartilage. There was no infraorbital foramen, and the infraorbital neurovascular bundle was distributed instead to the palate. Clinical and functional correlations of the various defects are considered. Theories of pathogenesis are discussed on the basis of these findings. It is argued that these observations could be accounted for by an altered intercellular matrix with separate effects on skeletal growth and neural crest cell migration.     

下颌骨髁突支架的个体化设计与初步构建

Objective To explore the method of designing and manufacturing the mandibular condyle scaffold individually by rapid prototyping technologies and reverse engineering.Methods Cranial CT image data were processed in Mimics software for reconstruction of one side of ramus of mandible, and were inputted into Solidworks software to edit by the format of stl. A negative mold of the mandibular condyle scaffold was obtained. The mold was fabricated by resin materials utilizing rapid prototyping. Biomaterials were filled into the resin mold. When the materials were cured, we eliminated the resin mold and acquired a multi-pores three dimensional mandibular condyle scaffold model. The general morphology and microstructure of the scaffold model were observed by scanning electron microscopy (SEM). Results The mandibular condyle scaffold made of biomaterials was accordance with the one our computer designed. SEM observation revealed that the model was made of collagen in the cartilage-like layer and calcium phosphate cement/poly (lactic- co-glycolic acid) in the bone-like layer. Conclusion It is feasible to fabricate mandibular condyle scaffold individually by using reverse engineering and rapid prototyping technology.     

Muscular dystrophy associated with extra-abdominal desmoid tumor showing aberrant chromosome 1 [46,XX,add(1)(p36)]

We report on a 2-year-old girl with probable limb-girdle muscular dystrophy associated with an extra-abdominal desmoid tumor of the right mandible. This association is previously undescribed. The tumor was totally removed. Cytogenetic analysis of the tumor showed a clonal karyotypic abnormality: 46,XX,add(1)(p36) in 3 of 20 cells analyzed. Since an association of a neoplasm with limb-girdle muscular dystrophy has previously been reported in 3 cases, the two abnormalities are likely related causally. The chromosome abnormality in our patient may play a role in the occurrence of her desmoid tumor. Am. J. Med. Genet. 76:42–44, 1998. © 1998 Wiley-Liss, Inc.     

髁突颈横行截骨和骨折对大鼠下颌骨生长发育的影响

目的 建立年轻SD大鼠单侧髁突颈部截骨、骨折的动物模型,探讨应力改变对大鼠下颌骨及髁突生长发育的影响.方法 4周龄72只雄性SD大鼠按随机数字表法分3组,每组24只,分为截骨组、骨折组、对照组.建立大鼠单侧髁突颈部横行截骨,骨折的动物模型,观察术后1、3、5、9周髁突影像学、组织学及下颌骨解剖学的变化.检测与髁突生长发育关系密切的结缔组织生长因子（CTGF）及X型胶原（Col X）在髁突软骨中表达的变化.结果 截骨组手术侧术后1、3周髁突区膨大,髁突颈呈分离影像.骨折组手术侧术后1周髁突呈圆柱状,见骨折线.截骨组手术侧术后4个时间点下颌骨生长发育受到限制,髁突软骨的总厚度术后1周代偿性增厚为（1468.28±53.73） μm,大于骨折组手术侧;术后3、5周总厚度明显降低;术后9周与骨折组手术侧比较差异无统计学意义（P＞0.05）,但都小于对照组（P＜0.05）.截骨组手术侧CTGF在髁突软骨中的表达在术后1、3、5周分别为60.18±1.23、72.43±2.82、86.00±2.90均高于骨折组手术侧和对照组Col X表达在术后1周时为64.46±3.76,高于骨折组手术侧和对照组（均为P＜0.05）.结论 单侧髁突颈截骨,致应力改变明显,影响下颌骨及髁突生长发育,可导致手术侧、非手术侧下颌骨的不对称,并影响CTGF及Col X在髁突软骨的表达.     

锥束CT测量安氏Ⅰ类错牙合人群下颌髁突的体积和表面积

背景：髁突是下颌骨的生长中心,髁突的体积大小对下颌骨的形态有着密切的关系,同时各种关节疾病都会导致髁突形态的变化。 目的：通过锥束CT测量年轻安氏Ⅰ类错牙合人群髁突体积和表面积,为中国人髁突体积和表面积提供正常参考值。 方法：从重庆医科大学附属口腔医院正畸科就诊患者中选取年龄在18~28岁之间的年轻安氏Ⅰ类错牙合患者70例,男34例,女36例。所取患者脸型左右对称,“↓”开口型,开口度正常,无关节弹响,疼痛等症状。所有患者接受锥束CT检查,通过Mimics 10.0对CT片髁突进行三维重建,计算髁突的体积,表面积以及形态指数(体积和表面积之比)。 结果与结论：男性髁突体积和表面积均显著大于女性(P < 0.01)。左右髁突体积和表面积差异无显著性意义(P > 0.05)。左右两侧髁突形态指数和男女髁突形态学指数差异无显著性意义。结果提示脸型对称,无关节症状的安氏Ⅰ类错牙合人群左右髁突基本对称。     

Clinical, biochemical, and neuropsychiatric evaluation of a patient with a contiguous gene syndrome due to a microdeletion Xp11.3 including the Norrie disease locus and monoamine oxidase (MAOA and MAOB) genes.

Norrie disease is a rare X-linked recessive disorder characterized by blindness from infancy. The gene for Norrie disease has been localized to Xp11.3. More recently, the genes for monoamine oxidase (MAOA, MAOB) have been mapped to the same region. This study evaluates the clinical, biochemical, and neuropsychiatric data in an affected male and 2 obligate heterozygote females from a single family with a submicroscopic deletion involving Norrie disease and MAO genes. The propositus was a profoundly retarded, blind male; he also had neurologic abnormalities including myoclonus and stereotopy-habit disorder. Both obligate carrier females had a normal IQ. The propositus' mother met diagnostic criteria for "chronic hypomania and schizotypal features." The propositus' MAO activity was undetectable and the female heterozygotes had reduced levels comparable to patients receiving MAO inhibiting antidepressants. MAO substrate and metabolite abnormalities were found in the propositus' plasma and CSF. This study indicates that subtle biochemical and possibly neuropsychiatric abnormalities may be detected in some heterozygotes with the microdeletion in Xp11.3 due to loss of the gene product for the MAO genes; this deletion can also explain some of the complex phenotype of this contiguous gene syndrome in the propositus.     

Architecture and mineralization of developing cortical and trabecular bone of the mandible

Ossification of the presumptive trabecular bone in the mandibular condyle and the presumptive cortical bone in the mandibular corpus of the pig mandible was investigated during development, using micro-computed tomography (microCT). Three-dimensional architecture and mineralization characteristics were assessed from ten pigs of different developmental ages. In the condyle, increases in trabecular thickness and separation and a decrease in the trabecular number, led to an unchanged bone volume fraction. A conversion from rod-like into plate-like trabeculae was observed. Bone volume and trabecular thickness were always higher in the corpus, where an increase in bone volume fraction was caused by an increase in the trabecular thickness and a decrease in separation. A transition from a plate-like structure into a more compact structure took place. The average degree of mineralization in the condyle and the corpus increased with age. In the corpus, the degrees of mineralization were higher than in the condyle. The differences between the condyle and corpus and the changes with age could be explained by differences in the distribution of mineralization within the trabecular elements. Generally, the degrees of mineralization increased from the surface toward the centers of the trabecular elements, indicating growth of the trabecular elements by the surface apposition of new mineral.