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目的 研究快速扩弓时腭部种植体加强牙齿支抗的生物力学特征。 方法 2007年3月至12月，于吉林大学口腔医学院正畸科采用螺旋CT扫描，Mimics、Ansys软件处理相结合的方法，建立带有腭部种植体的上颌骨三维有限元模型。 结果建立了含有腭部种植体、腭中缝、上颌第一前磨牙和上颌第一磨牙及其牙周膜的上颌骨三维有限元模型。 结论 本实验所建立的三维有限元模型具有良好的力学和几何学相似性，可作为上颌快速扩弓时腭部种植体加强牙齿支抗的生物力学研究平台。     

微型种植体和横腭杆支抗用于成人正畸的疗效比较

目的 比较微型种植体和上颌横腭杆支抗用于成人正畸的效果.方法 选择20例成人上颌前突或双颌前突患者,随机分为两组,全部病例均拔除4个第一前磨牙并采用标准MBT技术矫正,分别使用微型种植体和上颌横腭杆加强支抗. 20例患者治疗前和拔牙间隙关闭后均拍摄头颅侧位片,比较两组磨牙在矢状向和垂直向的稳定性.结果 微型种植体组的磨牙前移量少,和上颌横腭杆组比较差异有统计学意义(P＜0.01).两组在垂直方向变化差异无统计学意义.结论 微型种植体支抗可以单独提供临床所需的最强支抗.     

腭部种植体在加强后牙支抗的三维有限元分析

目的 利用含腭部种植体的上颌骨三维有限元模型，探讨腭部种植体在加强后牙支抗时的位移及应力分布情况。方法 采用螺旋CT扫描、计算机图像处理及CAD术，建立含腭部种植体的上颌骨三维有限元模型。结果 在受力状态下，支抗种植体总体上是一种近中移动和垂直压低的复合运动；上颌第一恒磨牙的近中颊尖的腭向位移最大，远中舌尖的颊向位移最大，整体上表现为腭向倾斜及近中舌向扭转的运动趋势。结论 种植体骨界面应力最大处在种植体颈部；上颌第一恒磨牙出现复杂的三维空间内的运动。     

自攻型微螺钉种植体支抗的临床应用研究

目的 研究自攻型微螺钉种植体作为磨牙强支抗的临床应用效果.方法 在30例采用自攻型微螺钉种植体作为磨牙支抗的临床病例中,选择6例已经结束治疗的患者进行分析.6例患者均为骨性Ⅱ类上颌前突患者,拔除上颌双侧第一前磨牙后采用上颌强支抗进行矫治.选择自攻型微螺钉种植体作为上颌支抗,以内收上颌前牙、关闭拔牙间隙.种植体植入部位为上颌第二前磨牙与第一磨牙牙根间的颊侧牙槽间隔,加力值为每侧1.47～1.96 N.对患者拔牙间隙关闭前后的头颅定位侧位片进行分析,测量前牙内收情况和磨牙支抗的变化.结果 6例患者共植入12枚微螺钉种植体,矫治后其上颌前突症状均得到明显改善,上颌切牙切缘平均内收6.06 mm,支抗磨牙平均前移0.44 mm,均获得了磨牙强支抗效果.治疗中,种植体保持稳定,种植体周围的软组织健康.结论 自攻型微螺钉种植体支抗是一种简便、有效的支抗形式,可以满足正畸临床治疗的需要.     

微种植体支抗矫治上颌前突15例的X线头影测量研究

目的　评价微种植体在上颌前突患者正畸治疗中的支抗作用。方法　15例上颌前突患者,拔除上颌第一前磨牙后,使用微种植体支抗结合滑动法关闭拔牙间隙,对矫治前后的X线头颅定位侧位片进行测量,分析软硬组织的变化,采用SPSS 16.0软件包对数据进行统计学处理。结果　治疗后上颌中切牙切缘平均腭向移动6.52 mm,上颌第一磨牙近中接触点平均近中移动0.41 mm,上唇突点后移,鼻唇角加大,A点轻微后移,患者侧貌明显改善。结论　微种植体在关闭拔牙间隙过程中具有完全支抗作用。     

三种不同支抗形式拔牙矫治青少年双颌前突的临床研究

目的:比较横腭杆、Nance弓及两者联合使用三种支抗形式用于青少年双颌前突拔牙矫治的临床疗效.方法:选取12～17岁安氏Ⅰ类双颌前突患者32例,分为三组:横腭杆组、Nance弓组、横腭杆与Nance弓联合组,各组病例均在拔除4个第一前磨牙后,使用标准方丝弓固定矫治技术治疗,两步法关闭拔牙间隙,平均时间10.43个月.分析治疗前后X线头颅侧位定位片及牙颌模型的各项指标变化.结果:横腭杆组、Nance弓组、横腭杆与Nance弓联合组磨牙平均前移量分别为3.03 mm、2.93 mm、1.18 mm;在垂直向和水平向上三组支抗控制无显著性差异(P≥0.05);横腭杆与Nance弓联合组代表软组织侧貌的指标Ls-E、Li-E、Cm-Sn-Ls、Pg'B'-FH、A'L s-FH、Z角均有显著改变(P＜0.01).结论:横腭杆与Nance弓联合支抗在矢状向、垂直向、横向支抗控制较好,三维支抗控制优于单纯使用横腭杆组或Nance弓组,是一种简单有效的非依赖性口内强支抗;对于青少年双颌前突拔牙矫治病例是一种非常有效的支抗形式.     

两种不同联合支抗形式矫治双颌前突的临床研究

目的比较横腭杆与Nance弓以及横腭杆与滑动杆两种不同口内联合支抗系统矫治双颌前突的临床疗效。方法选取11～29岁双颌前突患者30例,分为两组:横腭杆与Nance弓联合支抗组、横腭杆与滑动杆联合支抗组,各组均拔除4个第一前磨牙,两步法关闭拔牙间隙,使用MBT直丝弓固定矫治技术治疗,分析治疗前后X线头颅侧位片各项指标变化。结果横腭杆与Nance弓联合支抗组磨牙前移量治疗前后有显著性差异,而横腭杆与滑动杆联合支抗组无显著变化;横腭杆与滑动杆组切牙牙根后移量大于横腭杆与Nance弓组,两组间有显著性差异。结论横腭杆与滑动杆联合支抗在矢状向控制及切牙整体移动方面较好,优于横腭杆与Nance弓联合支抗,可以作为一种有效的非依赖性口内强支抗矫治双颌前突拔牙的病例。     

Nance弓和横腭杆在拉尖牙远移中支抗效果的研究

目的:研究Nance弓和横腭杆在拉尖牙远移过程中,二者在三维方向上磨牙支抗效果的比较。方法:选择Angle I类中度拥挤,或Angle II类I分类软组织侧貌前突不明显者40人,随机分组,上、下颌减数双侧第一前磨牙,设计方案为中度支抗,两步法关闭拔牙间隙。排齐整平后和治疗阶段结束时取模型,拍摄口内像和头颅侧位片。测量各标志点的线距和磨牙角度变化。应用SPSS 17.0统计软件对测量结果行统计学分析。结果:2组在阻止上颌第一恒磨牙近中前移、水平宽度或垂直方向、近中倾斜差异无显著性,但在磨牙旋转的控制上,Nance弓组磨牙向近中舌向旋转3.70°±1.20°,横腭杆组向近中舌向旋转8.50°±3.59°(P<0.05)。结论:在磨牙旋转支抗控制上,Nance弓明显优于横腭杆。     

关闭拔牙间隙时配合应用上颌前牙种植体支抗垂直向控制的三维有限元研究

目的:关闭拔牙间隙时配合应用上颌前牙种植体支抗垂直向控制,研究不同压低方式上颌前牙及牙周膜的应力分布及上颌前牙的位移情况.方法:构建三维有限元模型,模拟关闭拔牙间隙时,在上颌前牙区的不同位置配合应用共0.5 N的垂直向压低力,对不同工况下牙齿的应力分布和位移情况进行分析.结果:配合应用上颌前牙种植体支抗垂直向压低力后,...     

含不同种植体的腭部三维有限元模型的建立

目的:通过建立一个含不同直径、不同长度种植体的上颌骨三维有限元模型,并进行应力分析,选出最佳的支抗种植体。方法:采用螺旋CT扫描、数字影像传输、CAD技术、UG和ANSYS软件相结合的方法,建立部分上颌骨三维有限元模型,将不同直径、不同长度的支抗种植体植入腭部。结果:建立了符合生物力学研究需要的含腭部种植支抗的部分上颌骨三维有限元模型,探索出一条数字化程度高的三维有限元建模方法。结论: 应用螺旋CT扫描、数字影像传输以及UG、ANSYS软件相结合的方法,建立含支抗种植体的部分上颌骨三维有限元模型是切实可行和有效的。模型与生物实体真实结构具有良好的几何相似性,为有限元研究提供科学的参考依据。     

Development and Biomechanical Investigation of a New Compound Palatal Arch

BACKGROUND AND AIM: There are many advantages in using a transpalatal arch in orthodontic treatment. In addition to the active movement of individual teeth, such an arch can be used to provide additional anchorage. The aim of this study was to further develop and improve both the clinical and the biomechanical properties of the conventional transpalatal arch. MATERIAL AND METHODS: Currently available compound material components form an established part of orthodontic therapy. The Compound palatal arch broadens the scope of this treatment system. The biomechanical effects of the newly developed Compound palatal arch were verified by comparing them with those of commercially available conventional transpalatal arches. The recently developed Compound palatal arch is made of one compound element: nickel-titanium/stainless steel. The specific dimensions and design of the nickel-titanium element are aimed at exploiting its superelasticity, even during active molar movement. The biomechanical investigation was carried out using six-component measuring sensors to register the forces and moments in the three spatial dimensions (x, y and z) at 37 degrees C. The following appliances were investigated: Goshgarian transpalatal arch, quad-helix appliance, Arndt memory expander, and Compound palatal arch. RESULTS: Transpalatal arches could not be inserted without the arch being under tension. This is particularly important when the arch is being used for anchorage purposes. The Goshgarian arch had to be classified as problematic for the movement of single teeth as the load/deflection rate was high. However, this can be utilized for anchorage purposes. The clinical advantage of a quad-helix appliance is the option for asymmetric tooth movement. CONCLUSIONS: This study showed that the quad-helix was effective for both unilateral and bilateral derotation as well as for transversal tooth movement. However, expansions should be confined to < or = 4 mm, and derotations to < 10 degrees, as forces and moments are otherwise not within the physiologic range. The Arndt memory expander displayed no advantages over either the quad-helix appliance or the Goshgarian transpalatal arch. Nor did it display any superelastic properties. The linear relationship, the relatively high forces and moments, and the lack of clinical adjustability cast doubts on the benefits of this appliance. The newly developed Compound palatal arch showed substantial advantages in molar derotation compared with conventional transpalatal arches. Superelastic properties were achieved through the design and positioning of the nickel-titanium element. Expansion with the Compound palatal arch was comparable with that with conventional transpalatal arches. The clinical advantage is in the fact that this appliance can be reactivated and that dental asymmetries can be treated.     

Anchorage effect of various shape palatal osseointegrated implants: a finite element study

The purpose of this study was to compare the anchorage effects of different palatal osseointegrated implants using a finite element analysis. Three types of cylinder implants (simple implant, step implant, screw implant) were investigated. Three finite element models were constructed. Each consisted of two maxillary second premolars, their associated periodontal ligament (PDL) and alveolar bones, palatal bone, palatal implant, and a transpalatal arch. Another model without an implant was used for comparison. The horizontal force (mesial 5N, palatal 1N) was loaded at the buccal bracket of each second premolar, and the stress in the PDL, implant, and implant surrounding bone was calculated. The results showed that the palatal implant could significantly reduce von Mises stress in the PDL (maximum von Mises stress was reduced 24.3-27.7%). The von Mises stress magnitude in the PDL was almost same in the three models with implants. The stress in the implant surrounding bone was very low. These results suggested that the implant is a useful tool for increasing anchorage. Adding a step is useful to lower the stress in the implant and surrounding bone, but adding a screw to a cylinder implant had little advantage in increasing the anchorage effect.     

Anchorage effects of a palatal osseointegrated implant with different fixation: a finite element study

The purpose of this study was to compare the anchorage effect of the osseointegrated implant with different fixation types using finite element analysis. Three fixation types were investigated. fixation type 1: implant neck in the oral-palatal cortical bone and implant tip in the cancellous bone; fixation type 2: implant neck in the oral-palatal cortical bone and implant tip in the nasal-palatal cortical bone; fixation type 3: implant neck in the oral-palatal cortical bone and implant tip projecting into the nasal cavity. Three finite element models were constructed. Each consisted of two maxillary second premolars, their associated periodontal ligament (PDL), alveolar bones, palatal bone, palatal implant, and a transpalatal arch. Another model without an implant was used to compare with the previous models. The horizontal force (mesial five N, palatal one N) was loaded at the buccal bracket of each second premolar. The stress was calculated in the PDL and implant surrounding bone. The result showed that the palatal implant could significantly reduce von Mises stress (maximum von Mises stress was reduced 30%) and evenly distribute stress in the PDL. The stress magnitude and distribution in the PDL was almost the same in the three implant models. These results suggest that different implant fixation types have almost the same anchorage effects.     

The use of an osseointegrated implant for orthodontic anchorage to a Class II Div 1 malocclusion.

This case report describes the use of an osseointegrated implant to maximize anchorage in a 24-year-old female orthodontic patient with an Angle Class II, Division 1 malocclusion. Preadjusted edgewise appliance therapy was performed by extraction of only the maxillary first premolars. The osseointegrated implant was placed in the median-sagittal region of the hard palate for maximum orthodontic anchorage and connected to maxillary first molar bands via a transpalatal arch. Total treatment time was 2 years and 8 months. Cephalometric superimposition revealed the achievement of maximum molar anchorage in the maxilla, resulting in satisfactory occlusal and facial improvements. Histological analysis of the implant-bone interface demonstrated that the fixture was successfully osseointegrated. In conclusion, the osseointegrated implant placed in the median-sagittal palate was shown to be an effective orthodontic system that can be used clinically as a rigid intraoral anchorage.     

Anchorage effect of osseointegrated vs nonosseointegrated palatal implants

Palatal implants can be used with a transpalatal arch (TPA) connected with the second premolar to provide anchorage. The purpose of this study was to compare the anchorage effects of an osseointegrated palatal implant (OPI) with a nonosseointegrated palatal implant (NOPI), using finite element analysis. One model, which was composed of two maxillary premolars, periodontal ligament (PDL), alveolar bone, a palatal implant, palatal bone, a bracket, band, and TPA, was created on the basis of the clinical situation. The palatal implant was treated as either NOPI or OPI. The force on the premolars was investigated under three conditions: a distomesial horizontal force, a buccolingual horizontal force, and a vertical intrusive force. The PDL stress was calculated and compared with a model without an implant. The result showed that OPI could reduce PDL stress significantly. (The average stress was reduced by 14.44% for the distomesial horizontal force, 60.28% for the buccolingual horizontal force, and 17.31% for the vertical intrusive force.) The NOPI showed almost the same anchorage effect as OPI. The stress on the NOPI surface was higher than that on the OPI surface, but the stress was not high enough to result in failure of the implant. These results suggested that waiting for osseointegration might be unnecessary for an orthodontic implant.     

Biomechanical considerations for total distalization of the maxillary dentition using TSADs

Class II malocclusions have traditionally been treated as nonextraction, extraction, or orthognathic surgery depending on the severity of the dental and skeletal discrepancies. To enhance function and improve esthetics with nonextraction treatment, functional appliances, tooth-borne molar distalization, and Class II elastics have been used, but they require patient cooperation and have drawbacks such as mesial movement of the anchor teeth, molar extrusion, and flaring of the incisors. Recently, with the application of temporary skeletal anchorage devices (TSADs) in patients with Class II malocclusions, clinicians have been able to achieve total distalization of the maxillary dentition without patient compliance and with less unwanted tooth movement. Before a clinician uses a TSAD, they must consider where to place it and what type to use for efficient, total arch distalization of the maxilla. TSADs such as miniscrews and miniplates can be inserted on the buccal and palatal sides for total arch distalization. When using them, the center of resistance of the entire maxillary dentition should be determined to obtain en masse movement of the maxillary dentition by a statically determinate force system. The treatment effects and the difference in biomechanics between buccal miniscrews and modified C-palatal plates (MCPPs) for total arch distalization of the maxilla are presented in this paper based on finite element and clinical studies. Additionally, a strategy for efficient total arch distalization with MCPPs is discussed along with considerations for the position of the second and third molars after total arch distalization.     

压低辅弓增加后牙支抗的临床应用研究

目的：研究压低辅弓在尖牙远移过程中增加后牙支抗的临床效果。方法：选择需要强支抗,上颌减数第一双尖牙的患者30例,随机分为研究组和对照组,每组15例,研究组采用上颌NANCE弓,配合0.017＂×0.025＂TMA压低辅弓,30°后倾弯,150g力远中牵引尖牙至第二双尖牙,对照组采用上颌NANCE弓,配合口外弓。将矫治前后的头颅侧位定位片和三维模型进行对比分析,其变化量进行独立t检验。结果：研究组在尖牙远中移动的过程中,右侧上颌第一磨牙近中移动0.77mm,近中腭向扭转8.9°;左侧上颌第一磨牙近中移动约0.72mm,近中腭向扭转8.8°;右侧上颌尖牙远中移动约5.5mm,远中腭向扭转10.3°;左侧上颌尖牙远中移动约5.71mm,远中腭向扭转15.1°。与对照组相比无显著性差异。且第一磨牙在前后向的位移与尖牙的位移和磨牙的扭转存在高度相关性。结论：30°后倾弯的压低辅弓在远中移动尖牙过程中,可以为后牙提供强支抗。     

Mechanics of palatal expansion in the occlusal plane

The mechanics of a transpalatal arch in the occlusal plane (symmetrical V-bends, asymmetrical V-bends and step-bends) is studied through four methods: simulation of the teeth movements with a typodont, measure of the forces and the moments with a mechanical system composed of pulleys and dead load devices, photo-elastic stress analysis, finite element stress analysis. Typodont experimentations display the dental movements: the easiest one is rotation; it is more difficult to observe distalization and mesialisation that occur with a version of the tooth. An experimental apparatus, composed of pulleys and dead load devices, allows to measure forces and moments released by a transpalatal arch, depending on the level of the activations. The authors notice that the distalization force for an asymmetrical V-bend activation is low, about 0.2 Newton for 5 degrees of activation. Photo-elastic stress analysis affords a visualization of the shear stresses induced by a transpalatal arch within the supporting structures of a root, thanks to the observation of colored fringes in a model constituted with two molars included in a birefringent resin. Meanwhile, the manipulation of the photo-elastic resin is not easy and the interpretation of the results remains difficult. The finite element method is a numerical analysis and consists in the fragmentation of the studied structure in a certain number of elements, where forces and moments can be applied: the three dimensional program analyses the stress and strains in these elements. Thus, we can: 1.--visualize strains and stresses of a transpalatal arch, when it is inserted in the lingual molar sheaths; 2.--observe the dental movements due to the activations of the transpalatal arch (rotation, version, mesialisation, distalization); 3.--study the stress induced in the periodontal tissue. The results of these studies are complementary and in agreement. Particularly, the second method (measure of forces and moments) and the finite element method provide a mathematical and visual model that could explain clinical results: thus, the main purpose of this research is to understand the orthodontic mechanics used in the edgewise or segmented technique.