两种颌托在颊侧多曲簧作用下对牙齿作用力的对比实验

目的　比较自凝树脂材料和热压膜材料制作的颌托,在颊侧多曲簧矫治力的作用下对上下颌中切牙的力值,以期选用合适材料代替自凝树脂制作颌托,为解决在临床应用颊侧多曲簧矫治器矫治安氏Ⅲ类错〖HT5”,7”〗牙〖KG-*3〗合〖HT5”〗畸形过程中,部分患者前牙出现的唇舌向倾斜问题提供参考。方法　口外模拟闭口位状态,将颊侧多曲弹簧依次矢状向打开2 mm、4 mm、6 mm、8 mm、10 mm,应用薄膜压力传感器微型测力系统,分别测量两种材料颌托在上、下颌中切牙产生的电压值,再依据关系式将电压值转化为力值,计算并比较两种材料颌托在不同长度多曲簧的矫治力作用下对上中切牙唇向、下中切牙舌向的力值大小,并对结果进行统计学分析。结果　随着颊侧多曲簧长度的增加,两种材料颌托对上颌中切牙唇向、下颌中切牙舌向的力值均增大;在颊侧多曲簧增加相同长度时,热压膜颌托对上颌中切牙产生的唇向力值和对下颌中切牙产生的舌向力值均小于自凝树脂颌托,P<0.05。结论　相较于自凝树脂,热压膜材料制成的颌托对上下颌中切牙的力值小,能够减少上下颌中切牙的倾斜,减轻牙效应。     

隐形矫治中不同附件及位置矫治扭转尖牙的三维有限元分析

目的 通过三维有限元法比较不同附件以及不同放置位置对隐形矫治器矫正左上颌尖牙扭转的影响。方法 通过扫描数据分别建立矫治器-附件-尖牙-牙周膜-松质骨-皮质骨(有附件组)与(无附件组)有限元模型。其中有附件组中的附件分为垂直矩形附件、垂直楔形附件、优化扭转附件,放置位置又分为颊侧中1/3、远中1/3以及颊-舌侧中1/3。将各组的矫治器以尖牙牙体长轴为旋转中心轴,将矫治器远中扭转2°,在MSC.Marc.Mentat软件中模拟运算,收集各应力、位移分布云图及最大应力、位移值。结果 ①无论有无附件,尖牙位移及牙周膜应力分布趋势相似,但附件组的尖牙位移值及牙周膜各种应力值均大于无附件组;②选用相同附件情况下,放置于颊侧中1/3的应力值和最大初始位移最高,颊-舌侧放置的应力和位移表达更加高效,远中1/3放置效果相对较差。结论 ①颊面中1/3与颊-舌侧放置应力值和最大初始位移量无明显差别,但是颊-舌侧放置矫治效果更加高效,消除了不必要的倾斜移动,对固位的要求也更低。②单牙模型中垂直矩形和垂直楔形附件矫治效果显著较优化扭转附件好,实际效果有待临床进一步验证。     

偏侧咀嚼对张闭口运动的影响

目的:分析偏侧咀嚼患者在最大张闭口运动中的下颌运动轨迹特征。方法:通过下颌运动轨迹描记检测技术,比较偏侧咀嚼和正常咀嚼人群在大张口运动中的运动轨迹,进行统计分析。结果:1)偏侧咀嚼组在大张口运动时开闭口轨迹多数分离,开口型与与双侧咀嚼组相比差异有统计学意义(P<0.05)。2)偏侧咀嚼组张闭口运动时垂直向和矢状向位移显著低于双侧咀嚼组(P<0.01)。结论:最大张闭口运动中偏侧咀嚼组开口型多数偏向工作侧,50%的人群开闭口轨迹分离,开口度减小,说明长期偏侧咀嚼会导致张闭口运动轨迹的异常。     

不同规格分牙簧的应力分析

目的 :分析不同规格分牙簧的应力 ,找出形状结构因素对分牙簧力学行为的影响规律。材料和方法 :研究用分牙簧由直径中 0 .4mm的澳丝弯制而成 ,分牙簧按龈臂的长短可分为七个型号。假设澳丝为各向同性、均质连续的线弹性材料。弓丝材料的力学参数 :弹性模量为 177Gpa、泊松比为 0 .3。应用有限元分析软件ANSYS对分牙簧的应力进行分析。首先对分牙簧进行单元划分 ,并输入材料性能参数。然后按力作用点的位移从小到大进行逐步加载 ,计算不同型号分牙簧在不同应变量时产生的应力。结果 :分牙簧的应力大小与力臂长短有关 ,力臂短产生的力就大 ,分牙簧的应力随位移的增加而增大 ,其变化可用公式F =A +BX表示。分牙簧应力变化回归方程不同型号分牙簧应力随位移的变化而有所改变 ,对于不同型号的分牙簧 ,应力随位移的增加而增大 ,不论力点在龈臂中点还是在龈臂端点 ,都有相同的变化趋势。位移相同时 ,龈臂中点产生的力比端点产生的力大。对数据进行回归分析 ,可得线性回归方程为F =A +BX ,结论 :研究了分牙簧应力随分牙簧尺寸、力作用点位移变化的规律 ,在临床上可以按照需要在一定范围内选择适宜的分牙簧以调节其作用力值。本研究表明 ,分牙簧的力臂越短 ,产生的力值越大 ,无论作用点在龈臂端点或中点 ,均显示     

一种可开大间隙的缺隙“维持器”

1．制作：①用0．6mm不锈钢丝自带环远中滑其中份紧贴带环弯制圈形结构，至近中缺隙侧牙冠颊舌经的中1／3与颊舌1／3交界处分别伸出调整两末端至平行，焊于带环上。钢丝两水平段的长度应比现有缺隙小2mm，再次调整两钢丝至平行。＠剪取两小段正晴用开大螺簧，其开大量等于间隙丧失量。③将磨去针头柄的12号针头圆管弯制成与两钢丝末端省间宽度一致的“二”型，弧形与另一侧邻牙有良好的接触。④装配并将螺簧压缩后用磷酸锌粘固剂将带环枯干牙上。2．典型病例：例1，男，45岁，缺牙三年要求修复。查：ed缺失，爿卜远中邻路面斜料，才卜近中倾…     

无托槽隐形矫治不同控根附件对磨牙近中移动力学影响的三维有限元分析

目的:利用三维有限元分析,探讨无托槽隐形矫治中不同控根附件在磨牙近中移动过程中的力学影响。方法:利用锥形束CT（CBCT）扫描获取上颌骨数据,采用Mimics、Geomagic、Solidworks和Ansys等软件建立包括左侧上颌第一磨牙及其牙周组织、隐形矫治器和不同控根附件的4个三维有限元模型,即模型A-无附件;模型B-颊侧垂直矩形附件;模型C-颊侧单个半圆柱形优化附件;模型D-颊侧双半圆柱形优化附件。模拟上颌第一磨牙在隐形矫治器作用下的近中移动,比较其周围牙周膜应力分布、位移模式和牙槽窝近中内表面应力分布。结果:颊侧双半圆柱形优化附件模型的近中牙周膜压力分布和近中牙槽窝应力分布最广泛,旋转中心最靠近根尖孔,其控根效果最好。颊侧垂直矩形附件牙周膜近中面压力分布靠颊侧明显比靠腭侧广泛,颊侧位移旋转中心比腭侧明显靠近根尖孔,说明此附件对颊侧控根效果优于腭侧。单个颊侧半圆柱形优化附件的牙周膜受力及位移模式与无附件相比无显著差别,但位移最大值更大。结论:添加控根附件后,增加了上颌第一磨牙近中移动的效率。颊侧双半圆柱形优化附件控根的作用优于传统矩形附件,但是所有的附件组合均使磨牙发生近中倾斜移动。     

双曲舌簧的改良及临床效果评价

双曲舌簧是口腔活动矫治器作用力部分最常用装置之一,可使牙齿产生舌侧或腭侧的移动,主要用于垫舌簧矫治器矫正牙齿的反.我们在临床应用中发现,双曲舌簧力量过大,衰减过快,并易于折断,且复诊间隔时间较短等缺点.笔者对其进行改良,应用于临床取得了较好的效果.用直径为0.5mm的弹性钢丝弯制即可,与传统的双曲舌簧结构基本相似,只有分别在双曲舌簧的两个"U”型弯处,变更为两个弯制的螺圈.螺圈的螺数为1-2个,直径为1.5-2.0mm,其结构相同、方向相反,使得形成的改良双曲舌簧整体操作可参照常规双曲舌簧之要求弯制.分别对两曲线中累积有效率%与矫治有效时间进行相关性检验(R=0.985,0.84690,P＜0.05),用两曲线的回归曲线方程分别计算出半数有效时间(T50%)值,其结果表明改良后双曲舌簧矫治疗程明显缩短,半数有效时间(T50%)由原来的8.10周降至4.85周,90%以上的病例在10周即显疗效,统计分析表明改良后双曲簧折断率,在各个时期都明显下降,即其可靠性和耐久性明显提高.改良双曲舌簧有以下优点1、改良双曲舌簧可以将较多机械能储存起来,并持久而缓慢的释放,更接近于"温和而持久”的这一矫治力的要求,延长了复诊的间隔时间,并相对地缩短了疗程.2、改良双曲舌簧产生的力量比相同材料弯制的常规双曲舌簧的力量更和缓,不易于折断,折断个数大大减小.3、改良双曲舌簧比普通双曲舌簧占有空间较小,减少了对舌的刺激性,使病人更易于接受矫治.     

用不锈钢丝弯制简易隔湿夹

<正> 隔湿是临床牙科治疗技术不可缺少的步骤,基层口腔医疗机构大多无橡皮障隔湿设备,且操作程序较复杂。单用吸水棉卷隔湿常因舌体及颊部运动而易于滑出,尤其是小儿,配合较差,唾液分泌又多,隔湿有一定困难。我科因陋就简,用“牙用不锈钢丝”弯制隔湿夹,对隔湿起到一定作用,同时也限制了患者不自觉的闭口动作。经临床使用,效果满意。此夹制作简单,操作方便,非常适合基层医疗单位。制作方法:取一段1.2mm不锈钢丝约20cm长,在中间位置用技工梯形钳环绕两周半形成弹簧部分。在两端距弹簧部位约2.5cm处相互交叉至对侧,同时各向两侧方弯制出“U”形翼部分。末端各焊接一与牙体颊舌侧弧度相一致的半环卡,作为固位部分。制作即完     

差动直丝弓矫治技术打开咬合过程中不同磨牙后倾弯曲度对下颌前牙及牙周膜应力分布的影响

目的：研究在差动直丝弓矫治技术打开咬合过程中,不同下颌磨牙后倾弯角度对下颌前牙应力分布及位移趋势的影响。方法利用志愿者锥体束CT,建立下颌牙列和差动直丝弓矫治器的三维有限元模型,模拟下颌30°、35°、40°和45°四种后倾弯,对模型加载进行有限元分析。结果下颌前牙牙根和牙周膜所受应力均随后倾弯度数增大而增大,当后倾弯角度大于40°时应力出现减小,其应力分布符合非控制性倾斜移动的特点。下颌前牙的初始位移趋势随后倾弯的增大而增大,当大于40°时初始位移趋势开始减小。下颌尖牙在颊舌向上表现为冠颊倾,下颌切牙冠唇倾,在垂直向上表现为先尖牙再切牙的顺序压低,在近远中向均表现为冠近中移动趋势。结论在差动直丝弓打开咬合阶段,通过调整磨牙后倾曲的角度可获得下颌前牙段适宜的压入以及匹配的上下颌牙弓宽度。     

无托槽隐形矫治矩形附件对上颌磨牙远中移动力学影响的三维有限元分析

目的:建立无托槽隐形矫治远移上颌第二磨牙的三维有限元模型,计算牙周膜应力分布及第二磨牙位移趋势,为无托槽隐形矫治器远中移动上颌第二磨牙位移量、附件设计提供理论依据。方法:通过CT扫描获得患者上颌骨DICOM文件,采用Mimics、Geomagic Studio等软件分别建立无附件上颌第二磨牙远中移动0.2 mm(模型A)、无附件上颌第二磨牙远中移动0.25 mm(模型B)、上颌颊侧尖牙和第一磨牙临床冠中心粘贴垂直附件上颌第二磨牙远中移动0.2 mm(模型C)、上颌颊侧尖牙和第一磨牙临床冠中心粘贴垂直附件上颌第二磨牙远中移动0.25 mm(模型D)4组模型,分析牙周膜应力及其上颌第二磨牙移动趋势。结果:A、B、C和D 4组模型第二磨牙牙周膜应力分布云图相似,牙周膜牙颈部唇侧将近1/3为压应力,舌侧将近1/3为拉应力,根中部为应力过渡区,牙根唇侧将近1/3为拉应力,舌侧将近1/3为压应力;4组模型第二磨牙均呈现一定程度远中倾斜移动,垂直矩形附件组移动的位移量较大,且远中倾斜程度小于无附件组。结论:无托槽隐形矫治器远移上颌第二磨牙时,0.25 mm位移量应力大于0.2 mm,垂直矩形附件可抑制第二磨牙远中倾斜。     

Checking the cheek bite injury: fabrication of an interim cheek guard appliance

Among the various sequelae associated with the treatment of oral carcinoma (both surgical and radiotherapy), the two conditions that can be of serious concern are reduced mouth opening and mucositis. The limited mouth opening can lead to entrapment of buccal mucosa in between teeth during the chewing cycle, which in turn can lead to further injury of the mucosa. A simple method has been described by the authors to prevent the cheek bite by fabrication of a cheek guard appliance. Favorable results were seen within a few days after insertion of the appliance.     

Reduced joint distance during TMJ movement in the posterior condylar position

Biomechanical loading reduces joint distance and has a causative relationship with disc displacement in temporomandibular joint and/or osteoarthritis. Condylar movement and pathways during mouth opening and closing are different depending on the condylar position in the glenoid fossa. Therefore, physical loading on the articular disc or condylar head would also be different in different condylar positions. The aim of this study was to evaluate the 3-dimensional changes of joint distance in different anterior–posterior condylar positions. We divided 52 temporomandibular joints into anterior, concentric, and posterior condylar positions using transcranial radiographs. We traced the condylar movements by simulating mandibular movement with 3-dimensional computed tomography data and a position-tracking camera. The joint distance during temporomandibular joint movement was significantly narrower, and the length of condylar pathways with narrower joint distance was longer in the posterior condylar position than in the concentric (p < 0.05) or anterior condylar positions (p < 0.01). Our study suggests that the posterior condylar position experiences more physical loading than other positions. Therefore, the position may have an accelerating or worsening effect on biomechanical loading-related temporomandibular joint disorder in cases of harmful parafunctional activities such as excessive mouth opening, clenching, and bruxism.     

The intra-articular distance within the TMJ during free and loaded closing movements

Previous studies on free opening and closing movements of the mandible have demonstrated that the opening movement traces of the condylar kinematic center (i.e., the condylar point for which the protrusive and the opening movement traces coincide) lie closer to the articular eminence than the closing traces. This indicates the presence of an intra-articular distance within the joint during free closing. Since the mandible behaves like a class III biomechanical lever, a counteracting mechanical load on the mandible during closing will press the condyle-disc complex against the articular eminence. Therefore, in this study the hypothesis was tested that the difference between opening and closing movement traces of the kinematic center is reduced when the closing movements are counteracted by a mechanical load. From 10 healthy participants, 20-second movement recordings were obtained by a six-degrees-of-freedom opto-electronic jaw movement recording system (OKAS-3D) for three types of movements: (1) free opening and closing movements, (2) free opening and loaded closing movements (i.e., the participants closed against a small or high manually applied downward-directed force to the chin), and (3) gum chewing. Off-line, the opening and closing movement traces of the kinematic center were reconstructed, and the average difference between the traces (the intra-articular distance) was calculated. The average intraarticular distance was significantly smaller during loaded closing than during free closing, whereas no significant differences were found in the intra-articular distances between the loaded situations of low and high manual loading and contralateral chewing (ANOVA and post hoc Bonferroni multiple comparisons of means test, p<0.005). In conclusion, loading of the mandible during closing movements reduces the intra-articular distance within the temporomandibular joint.     

Rotational head motion concurrent to rhythmical mandibular opening movements

We have previously demonstrated the existence of a functional-rhythmical coupling between the head and the mandible using maxillary and mandibular incisal tracking points. However, that data did not provide information neither on the movement of the head as a whole nor on the location of its instantaneous centre of rotation. Thus, the objective of the present study was to determine whether the head undergoes a rotational motion during mouth opening and to locate its putative instantaneous centre of rotation. The same 6 d.f. (degree of freedom) measuring device employed in our previous studies was used again to analyse data from five male adults (age range: 26-29 years old) chosen as subjects. Concomitant head and mandibular movements were assessed in the sagittal plane by allocating several reference points in the head (upper incisor, cranial base, occipital and parietal points) and a mandibular incisor point during maximal mouth open-close movements. Then, the magnitude and inclination of the vectors of motion in each reference point during the opening phase were calculated. The instantaneous centre of rotation was defined as the point showing the least amount of motion in a determined area around each head reference point. The mandibular incisal point and the maxillary incisal point showed concomitant movements; that is, during opening the mandibular point moved downwards and the maxillary incisor point upwards. Making a large jaw opening movement caused an inferior-anterior displacement in the O point, a posterior-inferior displacement of the P point, and an anterior-superior displacement in the C point in all subjects. During jaw closing all points followed a trajectory opposite to that described above. In other words, during opening the head moved clockwise and counter-clockwise during closing, at least in the sagittal plane of the subjects' left side. These results suggest that the head undergoes a rotation-like sagittal movement during mouth opening whose rotation centre seems to be located above the cranial base point, which was set close to the centre of mass of the head. However, its location varies according to the magnitude of mouth opening.     

Development of an experimental optoelectronic device to study the amplitude of mandibular movements

This study aimed to present a wireless mandibular motion tracking device and optoelectronic data acquisition system developed to analyze the real-time spatial motion of the entire mandible during mouth opening and closing with no restriction of any movement. The procedures were divided into three phases: confection of a kinematic arch, dynamic digital video image acquisition, and image processing and analysis by using graphic computation. Four sequences of jaw opening/closing movements were recorded in lateral view: two from the maximum intercuspation (MIC) and the other two from a forced mandibular retruded position. Jaw motion was recorded by a digital video camera and processed as spatial coordinates corresponding to the position variation of the markers in the kinematic arch. The results showed that the method was capable of recording and processing the dynamics of the mandibular movements during jaw opening/closing using pixel-magnitude points. The mandible showed points with less displacement located near the temporomandibular joint during the opening/closing movements from the mandibular retruded position. When the jaw movements were recorded from MIC, these points were located near the mandibular foramen.     

Case report of a posterior disc displacement without and with reduction

This article presents the case of a patient with an acute posterior disc displacement without reduction (PDDWR), whose temporomandibular joint (TMJ) showed, after physiotherapeutic manipulation, the characteristics of a posterior disc displacement with reduction (PDDR). Opto-electronic condylar movement recordings in both the PDDR state and the PDDWR state, and magnetic resonance imaging (MRI) scans of the TMJ in the PDDR state were carried out to document the case. The first 2 physiotherapeutic manipulations were initially successful in reducing the disc, but a few days later the joint showed a relapse to the PDDWR state. From the third manipulation on, now 12 months ago, the patient has been free of symptoms of the PDDWR state. Condylar movement traces of the joint in the PDDWR state indicated that the condyle was prevented from entering the fossa completely. The downward condylar movement deflections during the early phase of closing, recorded after the second manipulation, showed the reduction of the posteriorly displaced disc during closing. The movement recordings also showed that the PDDR could be eliminated by submaximal opening and closing movements. The MRI scans, taken after the third, successful manipulation, showed the disc to be in a normal position with respect to the condyle when the mouth was closed, and to be posteriorly displaced when the mouth was maximally opened. The case shows that manipulation techniques may successfully reverse an acute PDDWR into a PDDR. The technique of MRIs and condylar movement recordings show promise in further unraveling the morphological and clinical features of posterior disc displacements.     

Micro-CT活体观察大鼠牙齿移动及复发过程的实验研究

目的:Micro-CT活体扫描连续观察不同矫治力引起的牙齿移动及复发的规律。方法:选择10周龄SD大鼠15只随机分成3组。对大鼠左侧上颌第一磨牙分别施加20 g、50 g、100 g的矫治力,持续加载14 d后卸载。在加力后的0、3、7、10、14 d和停止加力后3、7、10、14、28、42 d用Micro-CT对大鼠进行活体扫描,测量每个时间点牙齿移动的距离。结果:在加力后的0～3 d各组的磨牙都发生明显的近中移动,第3～10天,牙移动缓慢,第10天时20 g和100 g组移动距离快速增加。20 g组在矫治力去除后的0～3 d复发最多,50 g和100 g组在0～7 d复发最多,28 d几乎完全复发。结论:加载矫治力后牙齿呈现快速、缓慢、快速的移动规律,且轻力引起的牙移动更多。拆除加力装置的初期复发的最快,牙齿移动距离越大,复发越快。     

口周肌力在下颌支抗控制中的临床应用研究

目的 探讨口周肌力在下颌支抗控制中的应用。方法 临床上应用多曲不锈钢丝唇挡配合方丝弓固定矫治器对13例恒牙早期轻度牙列拥挤患者进行矫治,分析治疗前后支抗磨牙位置变化,观察支抗丧失情况。结果 利用口周肌力可以对支抗磨牙进行控制,防止支抗丧失。结论 可以在矫治过程中采用多曲唇挡来增强支抗。而且多曲唇挡制作简单,患者戴用舒适、隐蔽,容易获得患者的配合。