两种常用加力方式对种植钉压低上前牙力学行为影响的三维有限元分析

目的：使用三维有限元法分析种植钉压低上前牙时两种常用加力方式对上前牙力学行为的影响，为正畸临床提供生物力学依据。方法：建立含有托槽、弓丝、上前牙、牙周膜和牙槽骨的三维有限元模型。设定加力方式：方式1：起点为弓丝中点，终点为前鼻棘下。方式2：起点为中切牙与侧切牙间弓丝的中点，终点为与前鼻棘等高的中切牙与侧切牙间牙槽骨。分析牙周膜的主应力分布及牙齿的初始位移。结果：方式2的牙周膜应力分布更均匀。两种加力方式下，上切牙均发生唇倾。加力点两侧的牙齿向加力点倾斜。结论：将种植钉植入中切牙与侧切牙之间施加压低力更为合理。压低过程中需注意前牙转矩的控制，并使用较粗的不锈钢丝作为主弓丝。     

无托槽隐形矫治器整体内收上颌前牙的三维有限元分析

目的:研究无托槽隐形矫治器整体内收上颌前牙过程中上颌前牙所受的应力情况及初始移动规律.方法:采用CBCT扫描已拔除双侧上颌第一前磨牙患者,建立上牙列、牙周膜及牙槽骨的初始复合体模型.激光扫描患者牙冠外形并与初始模型三维重叠建立终模型.应用ANSYS Workbench软件分析安装无托槽隐形矫治器时上颌前牙的应力分布及初始位移趋势.结果:建立了具有高仿真度的上颌复合体三维有限元模型;上颌双侧中切牙及侧切牙初始位移趋势一致,表现为远中舌向倾斜移动,且均有伸长趋势,其牙周膜应力分布与其位移趋势相一致;上颌双侧尖牙表现为远中倾斜移动趋势.结论:无托槽隐形矫治器在整体内收上颌前牙时,上颌前牙均表现为倾斜移动,且有伸长趋势.     

J钩高位牵引压低并内收上颌前牙的三维有限元分析

目的 利用三维有限元方法探讨J钩高位牵引辅助压低并内收上颌前牙的生物力学机制,以期为临床治疗提供参考.方法 在ANSYS 14.0软件中建立包括上颌牙列、牙周膜、直丝弓矫治器及上颌骨的三维有限元模型.模拟J钩施加1.5 N力量压低内收上前牙,A组加载于侧切牙近中,B组加载于侧切牙远中.牵引方向与矢状面保持30°不变、与(牙合)平面的角度在20°～ 60°之间,每间隔5°设置1种工况,两组共18种工况.分析上前牙位移及牙周膜应力情况.结果 随着牵引角度增大,上前牙位移趋势逐渐由舌向移动为主伴压低的顺时针旋转移动,变为整体压低、内收移动,最后变为压低伴唇向倾斜的逆时针旋转移动.在侧切牙近中以35°加载或在侧切牙远中以45°加载时,上前牙出现相对均匀一致的整体压低、内收移动,整体无旋转的趋势.结论 对于唇倾度正常的上颌前牙,J钩高位牵引加载于侧切牙近中更有利于前牙的整体压低和内收,临床上应根据个体情况和治疗目标调整牵引角度.     

微型种植体正畸支抗的临床应用

目的 :初步应用验证 0SAS(OsseodyneSkeletalAnchorageSystem)微型螺钉种植体的正畸支抗能力。 方法 :选取微笑龈患者一名 ,在中切牙和侧切牙之间的根端上方植入两枚微型种植体 ,以每侧 5 0克力压低上颌前牙 ;选取两名需前后向后牙最大支抗患者 ,在上颌第一磨牙和第二前磨牙之间植入微型种植体 ,并以 10 0 15 0克力内收上颌前牙。结果 :微笑龈患者经 6个月治疗 ,上前牙压低 4毫米 ,唇齿关系良好 ;两名强支抗内收前牙患者 ,分别经 8个月和 9个月治疗 ,前牙内收量分别为 7毫米和 5毫米 ,患者面型得到明显改善。所有微型种植体在治疗期间均保持了稳定。结论 :OSAS微型螺钉种植体能够有效的承担垂直向和前后向支抗能力 ,实现切牙的绝对压低和最大限度的内收切牙。     

应用微种植体支抗压低上前牙改善露龈笑的临床研究

目的 探讨上颌前牙区微种植体支抗压低上前牙改善露龈笑的临床疗效。方法 选择露龈笑伴深覆患者15例,平均年龄（19.7±5.4）岁,在位于12,22近中根尖处颌骨内各植入1颗微种植钉,在方丝12,22近中置游离拉钩,向微种植钉做弹性牵引,每侧加力0.6 N,平均加力压低的时间为(6.2±1.6)个月。测量矫治前后X 线头颅侧位片的相关软硬组织指标,使用SPSSl3.0 软件进行统计分析。结果 前牙垂直压低的量及切牙牙冠长度明显减少（P＜0.01）,磨牙伸长量不显著。前牙的覆与覆盖均矫治达到正常范围。结论 微种植体做支抗压低上前牙、纠正深覆效果理想,能有效改善露龈笑。     

无托槽隐形矫治器配合微种植钉远移磨牙的三维有限元研究

目的 应用三维有限元模型研究无托槽隐形矫治器配合不同植入位置微种植钉远移磨牙时的初始上颌前牙位移及尖牙区应力分布情况。方法 选取于2021-02-16在大连市口腔医院正畸科就诊的需采用无托槽隐形矫治器行远移磨牙非减数正畸治疗的1例女性患者作为建模对象。构建三维有限元模型,模拟微种植钉位于第二前磨牙与第一磨牙之间、第一磨牙与第二磨牙之间,分别距离牙槽嵴顶4、6、8、10 mm的8种工况,并在微种植钉与尖牙唇面的舌侧扣之间加载1.47 N正畸力。分析加力1 s后8种工况的上颌前牙位移及尖牙牙周膜应力分布情况。结果 8种工况中,上颌中切牙均呈现牙冠唇向、牙根腭向的位移趋势;上颌中切牙牙冠唇向位移量随微种植钉高度的增加而减小,且微种植钉位于相对近中（上颌第二前磨牙与第一磨牙之间）时产生的位移量更小。8种工况中,上颌尖牙均呈现牙冠唇向、牙根腭向的位移趋势,且牙冠呈现唇倾趋势;上颌尖牙牙周膜最小主应力绝对值随微种植钉高度的增加而增大,且微种植钉位于相对近中时产生的最小主应力更大。结论 无托槽隐形矫治器配合微种植钉远移上颌磨牙时,配合本实验8种工况中相对近中的更高位微种植钉利于切牙转矩控制,配合相对...     

微型自攻钛钉种植体支抗压低切牙的初步应用研究

目的介绍微型自攻钛钉种植体用于正畸支抗的临床经验,评价自攻型微型钛钉种植体作为垂直向支抗压低前牙的有效性.材料方法在26例采用微型自攻钛钉种植体作为支抗手段的临床病例中,选择3名患者(年龄20-25岁),均表现为上颌或下颌前部牙齿槽发育过度,采用微型种植体支抗压低前牙.种植体植入上颌中切牙和侧切牙之间的牙槽间隔或下颌侧切牙和尖牙之间的牙槽间隔,每侧以50克力压低前牙.比较压低治疗前后的X线头颅侧位片,测量前牙切缘的压低量和转矩的改变量.结果所有病例治疗后前牙覆(牙合)达到正常,切缘平均压低4.3毫米,转矩平均增加9.8度.治疗过程中所有微型种植体均保持了稳定,种植体周围软组织健康.结论微型自攻钛钉种植体能够作为稳定的骨性正畸支抗,压低前牙,改善覆(牙合)和龈笑.并且具有操作简单灵活,可即刻加力,不依赖患者合作的优势.     

微钛种植支抗钉用于改善患者露龈笑的临床研究

目的 探讨微钛种植支抗钉用于改善患者露龈笑的效果.方法 随机选取20例露龈笑患者(微笑时露龈高度大于3 mm),两侧上颌侧切牙和尖牙之间的根方植入微钛种植支抗钉,植入后即刻加力,在上颌侧切牙与尖牙间弓丝上加牵引钩,微钛种植支抗钉与牵引钩之间用弹性牵引固垂直牵引,每例以0.49 N力压低上前牙.观察患者露龈笑的改善程度和种植支抗钉的稳定性.结果 20例患者治疗前后微笑时露龈高度度平均减少3.06 mm.治疗中微钛钉种植体支抗的稳定率为80％.中切牙牙冠变短(0.75±0.68) mm,侧切牙牙冠变短(0.52 ±0.23) mm,尖牙牙冠变短(0.55土0.28)mm,治疗前后中切牙、侧切牙和尖牙的牙冠长度差异有统计学意义(P＜0.05).结论 微钛种植支抗钉可有效地改善露龈笑问题,值得临床推广使用.     

不同前牙唇倾度及内收压低步距下隐形矫治器作用的比较：三维有限元研究

目的:应用有限元分析法探究使用隐形矫治器治疗不同前牙唇倾度以及不同内收压低移动步距下,以分步法内收前牙的牙齿移动特点。方法:建立使用隐形矫治器分步法内收上颌前牙的有限元模型,依据中切牙及侧切牙的唇倾度分为工况1:U1-SN=105°、工况2:U1-SN=115°、工况3:U1-SN=125°,牙齿移动总步距为0.2 mm,包括沿牙合平面的内收以及沿牙体长轴方向的压低,每组工况以内收量a:0.18 mm、b:0.14 mm、c:0.10 mm进行分组,分析上述不同情况下的牙齿移动特点。结果:在不同前牙唇倾度以及内收模式下,中切牙、侧切牙均表现为牙冠向舌侧、牙根向唇侧的倾斜移动,第二前磨牙至第二磨牙表现为牙冠向近中的倾斜移动。内收步距越大,前牙冠舌向位移量越大,前牙转矩改变量越大,第二前磨牙至第二磨牙牙冠近中移动量越大。结论:无托槽隐形矫治器在内收前牙时引起前牙的舌倾及伸长、后牙的近中倾斜,其移动量与内收步距呈正比,预设计的前牙绝对压低量无法抵消由牙齿内收引起的相对伸长量。     

微种植体支抗压低上前牙的Typodont实验研究

目的在Typodont模型上,模拟临床应用微种植体支抗压低上前牙的过程,研究不同部位支抗对上前牙压低效果的影响。方法制作上前牙槽骨垂直发育过度的标准Typodont模型42个,随机分为ABC三组,每组14个。A组在中切牙间植入微种植体,B组在中切牙和侧切牙间植入微种植体,C组在侧切牙和尖牙间植入微种植体,应用镍钛螺簧施0．98N（100g）力压低上前牙。应用三维坐标测量仪测量牙齿标记点的三维位置并获得点云数据,Imageware12软件测量牙齿的压低量及唇（颊）倾斜度,并同时拟合牙弓曲线,研究牙弓及[牙合]平面的变化。结果①三组中上前牙均有不同程度的压低（0．9220mm±0．3037mm～5．2354mm±0．9620mm）,中切牙的压低量〉侧切牙〉尖牙,微种植体的位置越靠前,压低效果越明显。②所有牙齿均向前移动,上前牙有不同程度的唇倾,微种植体的位置越靠后,牙齿向前移动越少,唇倾越少。③微种植体的位置越靠后,牙弓及[牙合]平面的变化越小。结论①应用微种植体支抗可以有效地压低上前牙,上磨牙并未伸长。②微种植体的位置越靠后,上前牙的压低量越小,唇倾越少,牙弓变化及[牙合]平面角减少的趋势越小。反之亦然。     

Comparison of anterior and posterior mini-implant-assisted maxillary incisor intrusion: Root resorption and treatment efficiency

Objective:To compare, through cone-beam computed tomography (CBCT), the root resorption and treatment efficiency of two different mini-implant-assisted modalities in intruding the maxillary incisors.Materials and Methods:Thirty-two adults who had deep bite and elongated maxillary incisors were randomly allocated to two groups: anterior mini-implant group (AMG) and posterior mini-implant group (PMG). In the AMG, approximately 40 g of force was applied per side with elastic chains from mini-implants placed between the lateral incisors and canines and in the PMG, with beta-titanium wires from mini-implants placed between the second premolars and first molars. This study was conducted on CBCT scans taken before intrusion and after 4 months of intrusion. Data were analyzed by means of a paired t-test, independent t-test, and Pearson’s correlation test.Results:One patient was excluded from the AMG due to mini-implant loosening. While the incisors showed a significant reduction in length and volume, this amount was greater in the AMG, especially in the central incisors (P < .05). Together with the mean intrusion rates of 0.62 and 0.39 mm/mo in the AMG and PMG respectively, the center of resistance of the incisors showed distal movement with labial tipping; these changes were greater in the PMG (P < .001). Volumetric root resorption was correlated with the amount of intrusion (P < .05).Conclusions:Intrusion anchoring from posterior mini-implants is preferred in cases of upright incisors, as the use of such mechanics directs the roots into the spongiosa where they undergo less root resorption and more labial tipping.     

Changes in maxillary incisor dental pulp blood flow during intrusion by mini-implants

Aim. The aim of this clinical study was to identify changes in pulpal blood flow (PBF) in human central incisors resulting from short- and long-term intrusive orthodontic forces from mini-implants. Materials and methods. A total of 40 sound upper central and lateral incisors in 20 patients scheduled for intrusion for orthodontic reasons were divided into two groups. From each group, 20 teeth were subjected to intrusive force from mini-implants (Group 1 = Light Force: 40 g; Group 2 = Heavy Force: 120 g), whereas the remaining 20 contralateral teeth were not subjected to forces from mini-implants and served as controls. Laser-Doppler flowmetry (LDF) measurements were recorded at baseline and at 3 days and 3 weeks following intrusion. Results. PBF decreased significantly at 3 days (Light Force Group: 7.72 ± 0.50; Heavy Force Group: 7.72 ± 0.52) and then increased towards baseline at 3 weeks (Light Force Group: 10.37 ± 0.58; Heavy Force Group: 10.31 ± 0.45) following intrusion. Conclusions. In other words, despite slight regressive changes in pulpal tissue in the short-term, PBF improved after 3 weeks following intrusion by mini-implants, indicating that the changes observed in PBF is reversible, even following radical incisor intrusion.     

Force changes associated with different intrusion strategies for deep-bite correction by clear aligners

Objectives:To investigate the relationships among different intrusion patterns of clear overlay aligners and the corresponding orthodontic forces and to provide guidance for clinical treatment.Materials and Methods:Five sets of removable thermoplastic-formed aligners with the same thickness, designed for different intrusion procedures (G0 aligners as a control group, with no activation; G1 aligners for intruding canines; G2 aligners for intruding incisors; G3 aligners for intruding canines and incisors with the same activations; G4 aligners for intruding canines and incisors with different activation), were manufactured, and the corresponding intrusion forces were measured with a multiaxis force/torque transducer measurement system in real time.Results:With the same activation (0.2-mm intrusion) and rectangular attachments placed on the premolars and first molars, the canines experienced the largest intrusive force when intruded alone using G1 aligners. The canines received a larger intrusive force than incisors in G3. The incisors received similar forces in G2 and G3. First premolars endured the largest extrusive forces when all anterior teeth were intruded with G3 aligners. Extrusion forces were exerted on canines and lateral incisors when using G4 aligners.Conclusions:Aligners with different intrusion patterns exert different forces on incisors, canines, and premolars, and the forces were closely related to the designed activation, shape and position of the attachment and relative movement of the adjacent teeth.     

附件对隐形矫治器内收上前牙影响的三维有限元分析

目的    通过拔除上颌第一前磨牙后前牙内收的隐形矫治三维有限元模型,分析切牙上设置附件对牙齿移动方式的影响。方法    基于1例成年患者颌骨的锥形束CT影像数据,按照切牙上有无附件,构建4组拔除第一前磨牙的上颌隐形矫治模型,分别为切牙无附件组、侧切牙单附件组、中切牙单附件组和双附件组;导入Ansys Workbench三维有限元软件,设置4个上切牙控根压入内收的隐形矫治过程,分析牙列初始位移和附件的应力分布。结果    切牙无附件组及中切牙单附件组均发生4个切牙的舌向倾斜移动,后牙产生不同程度的近中倾斜移动,尖牙近中倾斜伴有伸长;侧切牙单附件组及双附件组切牙呈整体内收压入移动趋势,切牙附件的龈方可观测到压应力集中。结论    隐形矫治内收上前牙时,在侧切牙放置附件有助于切牙整体内收的表达,而中切牙附件对牙移动方式的影响较小。     

Effectiveness of an anterior mini-screw in achieving incisor intrusion and palatal root torque for anterior retraction with clear aligners:: A finite element study

ObjectivesTo analyze the biomechanical system of anterior retraction with clear aligner therapy (CAT) with and without an anterior mini-screw and elastics.Materials and MethodsModels including a maxillary dentition (without first premolars), maxilla, periodontal ligaments (PDLs), attachments, and aligners were constructed and imported to finite element software. Three model groups were created: (1) control (CAT alone), (2) labial elastics (CAT with elastics between the anterior mini-screw and buttons on central incisors), and (3) linguoincisal elastics (CAT with elastics between the anterior mini-screw and precision cuts on the lingual sides of the aligner). Elastic forces (0–300 g, in 50 g increments) were applied.ResultsCAT alone caused lingual tipping and extrusion of the incisors. Labial elastics caused palatal root torquing and intrusion and mesial tipping of the central incisors, while linguoincisal elastics produced palatal root torquing and intrusion of both central and lateral incisors. Second premolars were intruded in all three groups, with less intrusion in the linguoincisal elastics group. For the control group, stress was concentrated on both labial and lingual root surfaces, alveolar ridge, and cervical and apical PDLs. Stress was more concentrated in the labial elastics group and less concentrated in the linguoincisal elastics group.ConclusionsCAT produced lingual tipping and extrusion of incisors during anterior retraction. Anterior mini-screws and elastics can achieve incisor intrusion and palatal root torquing. Linguoincisal elastics are superior to labial elastics with a lower likelihood of buccal open bite. Root resorption and alveolar defects may occur in CAT, more likely for labial elastics and less likely for linguoincisal elastics.     

Maxillary molar intrusion using mini-implants in the anterior palate – “Mousetrap” versus “Mini-Mousetrap”

Supra-erupted maxillary molar teeth pose a major restorative challenge when attempting to prosthetically rehabilitate a partially edentulous mandibular dental arch. Traditional approaches with conventional tooth-borne appliances usually entail undesirable side-effects, including extrusion of adjacent teeth. Temporary anchorage devices (TADs), often inserted in the alveolar process, should help to minimize this phenomenon. The interradicular placement of mini-implants positioned between the roots of the maxillary molars has a number of inherent disadvantages and limitations. The preferred site for insertion of mini-implants is the anterior palate, which ensures a low risk of failure and mini-implant fracture. The ‘Mousetrap’ appliance is comprised of two mini-implants in the anterior palate, with attached lever arms for molar intrusion and a transpalatal arch (TPA) to avoid unwanted palatal tipping of the molar to be intruded. The ‘Mini-Mousetrap’ appliance was designed as a pared-down version without a TPA. If a TPA is not used, molar movement must be closely monitored, and the line of force action may need modification in order to minimize unwanted molar tipping.     

细丝弓技术舌侧内收上颌前牙的三维有限元生物力学分析

目的 建立细丝弓舌侧内收上颌前牙的三维有限元模型,研究不同后倾曲力矩对上颌前牙牙周膜静水压以及初始位移的影响。方法 采用CT扫描法建立包含全牙列头颅的三维几何模型,用Solidworks软件生成舌侧托槽和弓丝的三维几何模型,组装并生成细丝弓舌侧内收上颌前牙的三维有限元模型。在三维有限元计算软件ANSYS中计算当颌间牵引力为0.556 N,后倾曲力矩分别为15、30、45、60、75 Nmm时上颌前牙的初始位移以及牙周膜静水压。结果 上颌中切牙、侧切牙以及尖牙的唇舌侧根尖和颈缘共产生4个应力集中区,并产生远中方向的旋转初始位移和相对压入移动;上颌尖牙牙周膜的静水压应力和初始位移均显著大于中切牙和侧切牙;随着后倾曲力矩的增加,上颌中切牙、侧切牙和尖牙垂直向的初始压入位移和牙周膜静水压应力均逐渐增加。结论 采用细丝弓技术舌侧内收上颌前牙的力系是安全可控的,通过改变弓丝后倾曲力矩的值可以有效控制牙齿移动的方式和移动量。     

191例福建居民上颌前牙解剖长度及宽度分析

目的: 通过锥形束CT（cone-beam CT, CBCT）测量分析,了解福建居民上前牙解剖学特征,为进行上颌前牙区修复提供参考。方法: 利用CBCT测量191例就诊于福建医科大学附属口腔医院门诊患者的1 146颗上前牙（中切牙、侧切牙、尖牙）各牙位的长度及宽度,根据性别进行分组,量化分析牙体解剖特征的参数比例（宽长比及宽度比）。采用SPSS 19.0软件包对数据进行统计学分析。结果: 男性中切牙、尖牙的宽度和长度大于女性,差异有统计学意义（P<0.05）,男性、女性侧切牙的宽度和长度无显著差异（P>0.05）;男性、女性上颌前牙的宽长比值无显著差异（P>0.05）,宽度比值差异有统计学意义（P<0.05）。结论: 临床上应充分考虑患者地区、种族及性别差异,以更好地进行上颌前牙修复。