第三磨牙对下颌角、髁突骨折的影响及其三维有限元分析

发布时间：2018-05-26 22:04

本文选题：下颌角骨折 + 髁状突骨折　；参考：《大连医科大学》2016年硕士论文

【摘要】：目的下颌骨因其解剖结构及所处位置常易发生骨折,其中,下颌骨髁状突、下颌角因处在力学薄弱区而成为骨折好发部位。有学者进行了统计,下颌第三磨牙存在或阻生与髁状突、下颌角区骨折的发生率具有某种联系,认为下颌第三磨牙可能是下颌角发生骨折的危险因素[1],这种说法在许多文献和临床当中得到认可。而当下颌第三磨牙的缺失时,则可能产生力学传导变化,引起髁突骨折,究其原因,可能是下颌第三磨牙存在时,因下颌角区骨折发生后,髁状突部位遭受的外力得以缓冲,继而降低了下颌骨髁状突骨折的发生率[2],反之,亦然。本研究通过对下颌骨骨折的回顾性分析寻找不同部位骨折是否与下颌第三磨牙存在与否之间是否存在相关性,并通过三维模型进行有限元分析,外力撞击模拟骨折过程,观察应力分布。方法本研究通过收集整理大连医科大学附属第一医院口腔科在2010-2015年间298例下颌骨骨折的病例,探究下颌第三磨牙存在与否与髁状突部位、下颌角区骨折之间可能存在的关系;应用Mimics17.0、Geomagic12.0,结合CT影像资料,建立下颌三维模型,利用有限元分析软件Abaqus6-12,成功改建单侧下颌第三磨牙缺失,对侧同名牙正常萌出的模型,对髁状突及咀嚼肌群附着区进行约束,在下颌最突出的颏正中加载2000N水平方向力,观察双侧下颌骨应力分布变化。1.临床资料统计:下颌骨骨折好发于男性,男女比约6:1,青壮年居多,最常见的病因为交通意外;骨折常伴发颌面部其他部位的骨折,其中上颌骨骨折发生率较高,下颌骨骨折的好发部位是下颌颏孔区及髁状突,其余为下颌体部、下颌角和下颌支。存在下颌第三磨牙时易发生下颌角骨折,无下颌第三磨牙存在时易发生髁状突骨折。2.有限元分析法结果表明:第三磨牙存在侧下颌角区较对侧应力更为集中,高出约10MPa,第三磨牙缺失侧髁突区域的最大应力值为1728MPa,第三磨牙存在侧最大应力值为1618MPa,下颌第三磨牙的存在与否确实影响了下颌角、髁突的应力分布。讨论下颌骨骨折的流行病学分析较前人研究结果无显著变化,第三磨牙存在时下颌角骨折发生率较高,推测与下颌角区骨横截面面积相对减少有关;反之,第三磨牙缺失时应力向髁突区域集中,导致髁突易发生骨折。利用下颌骨三维模型,结合有限元分析法,模拟下颌骨骨折情况与实际近似,说明有限元分析法在参数设定合理下可较真实反映实际力学情况,这种方法可应用到相关研究当中。
[Abstract]:Objective the mandible is prone to fracture because of its anatomical structure and location, among which the mandibular condyle and the mandibular angle are prone to fracture because they are in the weak area of mechanics. Some scholars have made statistics that the existence or impaction of mandibular third molar is related to the incidence of condylar fracture and mandibular angle fracture. The conclusion that mandibular third molars may be a risk factor for fracture of mandibular angle [1] has been accepted in many literature and clinic. When the mandibular third molar is missing, the mechanical conduction may change, which may cause the condylar fracture. The reason may be that when the mandibular third molar exists, the external force of the condylar process is cushioned after the fracture of the mandibular angle region occurs. The incidence of mandibular condylar fracture was reduced [2] and vice versa. Through the retrospective analysis of mandibular fracture whether there is a correlation between the fracture of different parts and the existence of mandibular third molar or not and the finite element analysis of three-dimensional model external force impact simulation fracture process. Observe the stress distribution. Methods 298 cases of mandibular fracture in Department of Stomatology of the first affiliated Hospital of Dalian Medical University from 2010 to 2015 were collected to investigate the possible relationship between the existence of mandibular third molar and the position of condyle and mandibular angle fracture. Using Mimics17.0 and Geomagic 12.0, a three-dimensional mandibular model was established with CT image data. The model of unilateral mandibular third molar missing and contralateral condyle and masticatory muscle group attachment was successfully reconstructed by using the finite element analysis software Abaqus6-12, and the condyle and masticatory muscle group attachment region were restrained. The stress distribution of bilateral mandible was observed by loading 2000N horizontal force in the middle of the mandible. Statistics of clinical data: mandibular fractures are more common in males, with a ratio of about 6: 1 between males and females, the most common cause of which is traffic accidents, and fractures are often accompanied by fractures in other parts of the maxillofacial region, in which the incidence of maxillary fractures is higher. The most common sites of mandibular fracture were mandibular mental foramen and condyle, and the rest were mandibular body, mandibular angle and mandibular branch. Mandibular angle fracture is easy to occur in the existence of mandibular third molar, and condylar fracture is easy to occur when there is no mandibular third molar. The results of finite element analysis showed that the stress of the third molar was more concentrated in the lateral mandibular angle region than in the opposite side. The maximum stress of the condylar region of the third molar is 1728 MPA, and the maximum stress of the third molar is 1618 MPA. The existence of mandibular third molar does affect the stress distribution of the mandibular angle and condylar process. The incidence of mandibular angle fracture was higher when the third molar was present, which was related to the relative reduction of the cross section area of mandibular angle, whereas the incidence of mandibular angle fracture was higher when the third molar was in existence, whereas, there was no significant change in the epidemiological analysis of mandibular fracture. When the third molar is missing, the stress is concentrated in the condylar area, which leads to the fracture of the condyle. By using the three-dimensional model of mandible and the finite element analysis method, the situation of mandibular fracture is simulated, which shows that the finite element analysis method can reflect the actual mechanical situation more realistically under the reasonable setting of parameters. This method can be applied to relevant research.
【学位授予单位】：大连医科大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：R782.4

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