Effects of pulsed electromagnetic field vibration on tooth movement induced by magnetic and mechanical forces: a preliminary study

BACKGROUND: This study was designed to determine whether or not high-frequency and low-magnitude vibration affects orthodontic tooth movement caused by magnetic or/and mechanical forces. METHODS: Forty-four 7-week-old Wistar rats were randomly divided into four groups, with each group further divided into experimental and control subgroups. Neodymium-Iron-Boron (Nd-Fe-B) magnets and Sentalloy closed coil springs were placed between maxillary or mandibular first molars and incisors to activate tooth movement. The animals of experimental subgroups were exposed to the vibration induced by pulsed electromagnetic fields (PEMF) whilst the control subgroups were under normal atmosphere. The experiment lasted for 14 days and all of the animals were sacrificed for examination. The changes in the space between the molar and incisor were measured to indicate the amount of tooth movement. RESULTS: The coil springs, either with sham or active magnets, move molar much more than magnets alone, regardless of absence or presence of PEMF (p < 0.001). Under PEMF, the coil spring moved significantly more amount of tooth movement than that of coil-magnet combination (p < 0.01), as did the magnets compared to sham magnets (p < 0.019). Under a non-PEMF scenario, there was no significant difference in tooth movement between coil spring and coil-magnets combination, nor was there difference between magnets and sham magnets. CONCLUSIONS: It is suggested that the PEMF-induced vibration may enhance the effect of mechanical and magnetic forces on tooth movement.     

Influence of ibuprofen combined with corticotomy on tooth movement and alveolar bone remodeling in rats

ObjectivesTo investigate the effects of corticotomy-assisted orthodontic tooth movement and administration of ibuprofen on tooth movement rate and alveolar bone response.Materials and MethodsA total of 78 adult male Wistar rats were randomly assigned to five groups: one baseline group (no treatment) and four experimental groups including orthodontic tooth movement only (OTM), orthodontic tooth movement with ibuprofen (OTMI), corticotomy-assisted orthodontic tooth movement (COTM), and corticotomy-assisted orthodontic tooth movement with ibuprofen (COTMI). Corticotomy was performed on a maxillary molar unilaterally. Nickel-titanium closed-coil springs generated a 10-gram force for maxillary first molar movement. The experimental drug groups received 15 mg/kg of ibuprofen, and the other groups received reverse osmosis water. Tooth movement and bone volume fraction were evaluated by micro–computed tomography on days 0, 7, 14, and 21.ResultsThe corticotomy groups had statistically significantly higher tooth movement and lower bone volume fraction than the orthodontic groups (P < .05). The amount and rate of tooth movement were statistically significantly different between the OTM and OTMI groups, but not statistically significantly different in bone volume fraction. However, statistically significant differences were not observed in any measurements between the COTM and COTMI groups.ConclusionsIbuprofen during orthodontic tooth movement inhibited tooth movement and alveolar bone remodeling but had no effect on corticotomy-assisted orthodontic treatment.     

Numerical simulation of orthodontic bone remodeling

Orthodontic tooth movement is the result of alveolar bone remodeling due to response to mechanical stimulus at the interface with periodontal ligament. Therefore, periodontal ligament plays a critical role in the orthodontic tooth movement. The present study sought to develop a numerical model capable of simulating orthodontic bone remodeling. A three-dimensional finite elements model of mandibular incisor has been constructed based on CT data from a 15-year-old boy prior to orthodontic treatment. Simulations of orthodontic tooth movement were performed for tooth translation (bodily movement). The normal strain of periodontal ligament was assumed to be the key mechanical stimulus for alveolar bone remodeling. As bone remodeling is an iterative procedure, tooth position and the geometry of tooth supporting structures were updated at each iteration. The results indicated that the total amount of tooth movement after a 30-day therapy period was approximately 0.9 mm, which was in good agreement with clinical observations. Therefore, orthodontic bone remodeling, and consequently, orthodontic tooth movement can be simulated using finite elements method. These simulations can be used in treatment planning strategy and predicting clinical tooth movement.     

不同浓度1,25-二羟基维生素D3对大鼠正畸牙移动速度的影响

目的 研究牙周局部注射3种浓度的1,25-二羟基维生素D3[1,25-(OH)2D3]对大鼠正畸牙移动速度的影响.方法 成年健康雄性Wistar大鼠96只,随机分为对照组、A组、B组和C组,每组24只.在大鼠上颌左侧第一磨牙与上颌中切牙之间安放加力装置,每隔3 d注射药物10 μL.对照组注射生理盐水,A组注射10-10 mol/L的1,25-(OH)2D3,B组注射10-8 mol/L的1,25-(OH)2D3,C组注射10-6 mol/L的1,25-(OH)2D3,分别于加力后的第1、 3、 7和14天各组处死6只大鼠.制取标本后测量第一磨牙移动距离.结果 对照组、A组和C组大鼠在正畸牙移动过程中均存在明显的正畸牙移动减慢时期,B组大鼠观察到持续的牙移动而没有移动减慢时期.结论 在大鼠正畸牙移动过程中,应用一定浓度的1,25-(OH)2D3能促进正畸牙的移动. 10-8 mol/L的1,25-(OH)2D3能更有效地促进大鼠正畸牙的移动,避免正畸牙移动过程中缓慢时相的发生.     

Effects of drugs and systemic factors on orthodontic treatment.

Orthodontic tooth movement and bone remodeling activity are dependent on systemic factors such as nutritional factors, metabolic bone diseases, age, and use of drugs. Therefore, a comprehensive review of the effects of these factors on orthodontic tooth movement is attempted in this article. Systemic hormones such as estrogen, androgen, and calcitonin are associated with an increase in bone mineral content, bone mass, and a decrease in the rate of bone resorption. Consequently, they could delay orthodontic tooth movement. On the contrary, thyroid hormones and corticosteroids might be involved in a more rapid orthodontic tooth movement during orthodontic therapy and have a less stable orthodontic result. Drugs such as bisphosphonates, vitamin D metabolites, and fluorides can probably cause a reduction of tooth movement after the orthodontic force is applied. Nonsteroidal anti-inflammatory drugs have also been shown to reduce bone resorption. Long-term administration of these drugs may therefore delay the necessary bone response to respective tooth-borne pressure and should not be administered for long periods of time to patients undergoing orthodontic tooth movement. Attention has also been focused on the effects of prostaglandins and leukotrienes in orthodontic tooth movement. It seems that they might have future clinical applications that could result in enhanced tooth movement. The use of the above drugs should be considered by every dentist in evaluating the treatment time and in planning treatment when tooth movement is attempted.     

正畸移动后大鼠牙周炎牙整合素β1mRNA变化的实验研究

目的　研究正畸移动后大鼠牙周炎牙与正常牙整合素β1 mRNA表达的变化。方法　选用10周龄雄性成 年SD大鼠96只,随机分为正常牙组、牙周炎牙组,每组48只。分别在加力后0、1、2、3、5、7 d点处死动物,制备标 本,采用原位杂交检测牙周炎牙与正常牙正畸移动后β1 mRNA转录水平的变化。结果　正常牙组和牙周炎组加力 后各时间点的整合素β1 mRNA阳性强度均较加力前有明显增高(P<0·001);在加力各时间点,两组整合素β1 mRNA的表达强度均无显著性差异(P>0·05)。结论　在牙移动中,整合素β1 mRNA牙周组织破骨细胞上有强表 达,提示其与牙移动中牙周组织的稳定和改建有关。     

正畸牙移动困难相关因素研究进展

正畸牙移动是以牙周组织塑建为生物学基础的复杂生理过程。许多因素如口颌复合体的解剖特征、咬合干扰、机械因素及系统性因素等都可能对其造成影响,导致正畸牙移动困难。近年来,国内外学者非常关注牙移动困难相关因素的研究,但当前有关正畸牙移动困难的研究多为动物实验及回顾性研究,亟需高质量的临床试验及循证医学研究。许多正畸牙移动困难相关因素的作用机制尚存在争议,未形成一个普遍认可的完善理论体系,目前认为牙槽骨缺损、上颌窦、牙龈、牙根粘连、骨岛和摩擦力等因素都可能导致正畸牙移动困难。了解正畸牙移动困难的相关因素有助于正畸医生为患者制定更全面的个性化治疗方案,实现更高效、安全的牙移动。本文对目前正畸牙移动困难的相关因素作一综述,为正畸临床治疗提供参考。     

大鼠正畸性牙根吸收及牙齿移动差异的研究

目的建立大鼠正畸性牙根吸收模型,比较一个加力周期内不同加力时间及不同加力力值时大鼠牙齿的移动差异及牙根吸收情况。了解时间、力值与牙齿移动及牙根吸收的关系。方法选择月龄相同,体质量相近的SD雄性成年大鼠建立正畸牙移动模型,按不同加力时间分为1、3、5、7、10、14d组,按加力大小分为40g、60g、80g力组。测量不同组别正畸牙移动量,采用连续切片观察牙根吸收情况。结果各组牙齿移动距离不同;牙根吸收主要表达在根中1/3区域;吸收程度与加力时间及力值有关。结论1、成功建立大鼠正畸性牙根吸收模型。2、不同加力时间及不同力值各组牙齿移动距离存在显著差异。3、不同加力时间及不同力值组牙根吸收存在规律性。     

消炎痛对正畸牙齿移动中牙周组织超微结构的影响

目的：在细胞水平上进一步研究消炎痛影响正畸牙周组织改建与牙齿移动的机理。方法：通过扫描和透射电子显微镜（ＳＥＭ和ＴＥＭ），观察牙周组织细胞超微结构的改变。结果：ＳＥＭ和ＴＥＭ观察表明，２５ｇ力可引起兔切牙牙周组织细胞超微结构发生改变，在压力和张力侧均出现损伤和修复性反应，消炎痛对正畸牙周组织细胞超微结构变化的影响包括两方面，一方面抑制了牙周组织的炎症反应和损伤，另一方面也抑制了组织的修复过程，从而抑制了正畸牙周组织改建和牙齿移动。结论：消炎痛可以抑制牙周组织对正畸力的反应，使牙齿移动速度减慢，在临床治疗中，对长期服用消炎痛类药物的患者，可能因此影响矫治效果，应引起足够重视。     

锌对正畸牙槽骨改建影响的实验研究

目的:通过外源性补锌观察锌对兔牙正畸移植动的影响。方法：建立兔牙正畸移动实验模型。实验组每日肌注1％ZnSO4(4mg/kg体重）,对照组注射生理盐水。手术后14d测量牙齿移动距离并观察正畸牙周组织改建情况。结果：实验组兔牙移动距离与对照组相比具有显著性差异（P＜0．05）。光镜观察和图像分析显示实验组牙槽骨的改建活跃,张力侧新生骨的量明显高于高于对照组。结论：补锌可能通过直 接或间接作用,促进进正畸牙槽骨改建。     

正畸牙齿移动时骨形成蛋白变化的实验研究

目的：探讨正畸虎齿移动过程中骨形成蛋白（bone morphogenetic protein BMP)的分布，表面的变化，方法：采用MBP单克隆抗体免疫 化染色及计算机图像分析的方法对实验性兔正畸牙齿移动牙周组织中BMP的表达变化进行了定性，定量分析，结果：正畸牙齿移动过程中，张力区牙周膜BMP达高峰出现早于牙槽骨表面，与张力区比较，压力区BMP表达高峰出现较迟，结论：BMP参与正畸牙齿移动时的骨吸收和骨增生的骨改建过程，并发挥着重要的作用。     

持续力和间歇力对牙移动骨改建的影响

正畸矫治力的作用时间对牙移动和牙槽骨改建的速度有直接影响,国内外许多学者对此进行了研究。该文就持续力和间歇力对牙移动速度、牙周膜牙槽骨改建和牙体应力反应的影响作一简要综述。选择合适的正畸加力方式,有助于临床医师有效控制牙移动,缩短正畸疗程。     

Interventions for accelerating orthodontic tooth movement: A systematic review

Objective:To evaluate the effectiveness of interventions on accelerating orthodontic tooth movement.Materials and Methods:We searched the databases of PubMed, Embase, Science Citation Index, CENTRAL, and SIGLE from January 1990 to August 2011 for randomized or quasi-randomized controlled trials that assessed the effectiveness of interventions on accelerating orthodontic tooth movement. The processes of study search, selection, and quality assessment were conducted independently in duplicate by two review authors. Original outcome data, if possible, underwent statistical pooling by using Review Manager 5.Results:Through a predefined search strategy, we finally included nine eligible studies. Among them, five interventions were studied (ie, low-level laser therapy, corticotomy, electrical current, pulsed electromagnetic fields, and dentoalveolar or periodontal distraction). Six outcomes were evaluated in these studies (ie, accumulative moved distance or movement rate, time required to move tooth to its destination, anchorage loss, periodontal health, pulp vitality, and root resorption).Conclusion:Among the five interventions, corticotomy is effective and safe to accelerate orthodontic tooth movement, low-level laser therapy was unable to accelerate orthodontic tooth movement, current evidence does not reveal whether electrical current and pulsed electromagnetic fields are effective in accelerating orthodontic tooth movement, and dentoalveolar or periodontal distraction is promising in accelerating orthodontic tooth movement but lacks convincing evidence.     

骨皮质切开术辅助正畸治疗的研究进展

近年来,寻求正畸治疗的成年患者数量日益增多,如何加速正畸牙齿移动、缩短正畸疗程,并同时降低与正畸治疗时间较长相关的牙体、牙周疾病风险成为医生和患者共同关注的焦点。目前已报道的加速牙齿移动的方法中,经基础和临床研究证实,骨皮质切开术可有效加速正畸牙移动、缩短疗程并减少与正畸时间相关的牙体、牙周疾病,且其术式也随着临床操作、手术设备、计算机技术的更新和进步而变得更加微创、简便、精确、有效。文章就骨皮质切开术辅助正畸治疗的历史起源与发展、加速正畸牙齿移动的原理、术式变化、适应证与禁忌证、临床应用等方面做一综述。     

大鼠正畸牙齿移动过程中Smad1的表达和意义

目的：探讨BMP超家族的细胞内信号转导分子Smad1蛋白在大鼠正畸牙齿移动过程中牙周组织的分布和表达。方法：用ABC免疫组织化学法，检测实验性大鼠正畸牙齿移动过程中牙周组织Smad1的表达。结果：Smad1在正畸牙齿加力各个时期存在的特异的分布模式，与BMP有相似之处。结论：Smad1参与了大鼠正畸牙齿移动过程，可能介导了BMP在正畸牙齿加力区的信号。     

Effect of diabetes on orthodontic tooth movement in a mouse model

Orthodontic tooth movement is achieved by the remodeling of alveolar bone in response to mechanical loading. Type 1 diabetes results in bone remodeling, suggesting that this disease might affect orthodontic tooth movement. The present study investigated the effects of the diabetic state on orthodontic tooth movement. An orthodontic appliance was placed in normoglycemic (NG), streptozotocin-induced diabetes (DB), and insulin-treated DB (IT) C57BL6/J mice. Histomorphometric analysis and quantitative PCR of periodontium were performed. The DB mice exhibited greater orthodontic tooth movement and had a higher number of tartrate-resistant acid phosphate (TRAP) -positive osteoclasts than NG mice. This was associated with increased expression of factors involved in osteoclast activity and recruitment (Rankl, Csf1, Ccl2, Ccl5, and Tnfa) in DB mice. The expression of osteoblastic markers (Runx2, Ocn, Col1, and Alp) was decreased in DB mice. Reversal of the diabetic state by insulin treatment resulted in morphological findings similar to those of NG mice. These results suggest that the diabetic state up-regulates osteoclast migration and activity and down-regulates osteoblast differentiation, resulting in greater orthodontic tooth movement.     

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目的探讨淫羊藿总黄酮（TFE）对正畸大鼠牙齿移动及压力侧牙周组织的影响。方法本研究于2012年9月至2013年4月在山西医科大学口腔医院进行。选取8周龄雄性Wistar大鼠40只,建立正畸牙移动模型。按随机数字表法分为对照组（A组）和实验组（B、c、D组）,每组10只。从正畸加力第1天开始,A、B、c、D组分别灌服不同剂量TFE（依次为0、75、150、300mg／kg）,每天1次,第10天处死全部大鼠。测量大鼠左上第一磨牙移动距离,HE染色观察其压力侧牙周组织变化。结果A、B组牙齿移动距离差异无统计学意义（P〉O．05）;C、D组牙齿移动距离均明显小于A组（对照组）,差异有统计学意义（均P〈0．05）。HE染色显示,实验组正畸牙齿压力侧骨吸收陷窝少于对照组。结论’FFE可抑制正畸大鼠牙齿移动及压力侧牙槽骨吸收,且在一定范围内,剂量越大作用越明显。     

糖尿病大鼠正畸牙齿移动及组织学变化

目的 探讨糖尿病大鼠正畸牙移动对牙周组织的影响。方法 选用80只雄性SD大鼠，牵引左上颌第一磨牙近中移动。实验组以STZ腹腔注射制备Ⅰ型糖尿病模型，对照组注射柠檬酸缓冲液，3周后开始实验。分别在加力0、3、7、14、21天处死大鼠，记录上颌第一磨牙移动距离，组织HE染色后，观察牙周组织形态学的改变。结果 ①实验组大鼠牙齿移动距离在移动末期明显大于对照组；②实验组骨质疏松；③实验组大鼠压力侧破骨细胞数在骨吸收期少于对照组，3、7、14天有统计学意义；④实验组大鼠在骨形成期张力侧成骨细胞数少于对照组，14、21天有统计学意义。结论 ①糖尿病性骨质疏松导致正畸牙齿移动末期牙齿移动速度加快；②糖尿病骨质反应能力降低，牙齿移动过程中破骨活动和成骨过程均受抑制。     

Pulpal outcomes in orthodontic tooth movement in diabetes mellitus

Odontology - Diabetes mellitus impairs angiogenesis and tissue reorganization during orthodontic tooth movement (OTM). Thus, this study evaluated pulpal outcomes in orthodontic tooth movement...     

拔牙区骨改建对邻牙移动速度的影响

目的　本研究通过对拔牙创的骨改建进程及矫治力对牙齿移动的影响进行研究,为临床医生选择理想的矫治力和牙齿移动时机,缩短矫治时间提供依据。方法　取SD大鼠36只,随机分为3组,全麻下拔除一侧上颌第一磨牙,3月后拔除另一侧上颌第一磨牙。在拔牙后不同的时间制作口内矫治器,分别以0·30、0·60、1·36 N的力牵上颌第二磨牙向拔牙区移动,分别在施力前及施力后的第1、3、5、7、10、14天拍摄X线片,利用图像处理技术, 测量牙齿移动距离,以置入的拔髓针校正放大率。结果　①牙齿向新鲜拔牙区移动的速度明显大于向已愈合拔牙区移动的速度。②无论向新鲜拔牙区移动还是向已经愈合的拔牙区移动,0·30 N力组牙齿移动的距离在各时间点与0·60 N、1·36 N力组牙齿移动的距离之间存在显著的统计学差异;而0·60 N与1·36 N力组牙齿移动的距离之间基本上从第5天开始差别不大。③加力后牙齿移动周期一般包括三个阶段:瞬时运动;迟滞期;后期移动阶段。大约在第14天时,由于矫治力衰减,牙齿停止移动。结论　①牙齿向新鲜拔牙区移动速度快,而向已经愈合的拔牙区移动速度慢。②在矫治过程中,中等力较为合适;即使使用较大的力,也不一定引起较大的牙齿移动。