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。     

Effects of pregnancy on orthodontic tooth movements: effects of progesterone on orthodontic tooth movements in pregnant rats]

This study evaluated the periodontal responses and progesterone changes to orthodontic tooth movements in pregnant rats. Adult female Sprague-Dawley rats were separated into two groups: non-pregnant and pregnant. All rats were treated with fixed orthodontic appliances that moved the upper incisors in a distal direction during 10 days. At the end of the experiment, the periodontal tissues were examined histologically and immunohistochemically (ABC method). The results showed that in the histological examination of the tension sides of the upper incisors, the bone formation was more obvious in the pregnant group than that in the non-pregnant group. In the immunohistochemical staining, the osteoblasts were positive-stained cells and they exhibited deeper stain and higher percentage in the pregnant group. In a conclusion, the progesterone influences the periodontal reconstruction on orthodontic tooth movements in pregnant rats and may be helpful in alveolar bone formation, which suggests that orthodontic treatments in pregnant patients may not be so harmful as people thought before.     

内毒素局部注射干扰正畸牙移动的实验研究

目的 明确炎性牙周组织中细菌内毒素干扰牙移动及其牙周改建的分子机制，有助于指导牙周炎性受损患者的正畸治疗。方法 将P．g菌内毒素LPS局部注射于健康大鼠的磨牙牙根附近，观察牙移动2h-14d后的牙周变化。结果 实验发现正畸力作用下的的牙周改建受抑制，炎性反应明显加重，破骨细胞增生活跃：压力侧破骨细胞分化因子mRNA表达增强，在7d组时达到峰值。结论 LPS所致的炎性环境干扰了正畸牙移动，在破骨细胞形成和骨吸收中可能激活多种信号通路。     

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.     

低水平激光用于加速正畸牙齿移动的研究进展

以往研究表明,低水平激光治疗(low-level laser therapy, LLLT)可能具有加速牙齿移动的效果。笔者通过查阅文献,总结归纳了LLLT在加速牙齿移动方面的临床效果及其生物学机制。大多数研究认为,LLLT可加速牙齿移动。但也有一些研究认为LLLT不具有加速正畸牙齿移动的效果。LLLT具有小剂量刺激,大剂量抑制的特点。因此,结果差异可能与激光应用时的参数设置有关。LLLT通过光生物调节作用,促进牙齿周围骨组织的改建。研究表明,接受LLLT的患者,牙周组织中的骨细胞数、局部胶原蛋白量、炎症因子的表达情况等均出现差异,但具体的机制尚不明确,有待更深入的研究。     

增龄性因素对正畸牙齿移动影响的实验研究

目的:探索增龄性因素对正畸牙移动过程中牙周组织内HIF-1α及VEGF的影响。方法:建立不同年龄组的正畸牙齿移动动物模型,加力1 d、3 d、7 d、14 d及28 d,用免疫组化法检测牙周组织中HIF-1α及VEGF的表达情况。结果:青少年组大鼠实验侧压力区HIF-1α表达在加力1 d、3 d时明显高于成年组大鼠;VEGF表达量在加力1 d、3 d、7 d、14 d时明显高于成年组大鼠。结论:增龄性因素可使牙周组织对矫治力的反应速率降低,缺氧调控速率减慢,最终使牙槽骨改建减慢,牙移动速率降低。VEGF参与了正畸牙移动中组织改建过程,但成年组大鼠正畸牙齿移动过程中VEGF表达量增加缓慢,使牙槽骨改建速度降低,造成牙齿移动速度减慢。     

大鼠正畸牙移动过程中牙周组织内降钙素基因相关肽的变化

目的：了解大鼠正畸牙移动过程中牙周组织内降钙素基因相关肤(Calctionin gene—related peptide CGRP)的变化，探讨CGRP对正畸牙移动过程中的作用。方法：将35只雄性Wistar大鼠(体重240-280g)分为7组，其中一组未加力为对照组。选择右上第一磨牙作为实验牙，制备大鼠正畸牙移动12h、24h、3d、7d、14d、21d时牙周组织切片，进行免疫组织化学研究。结果：正畸牙移动过程中，牙周组织不同区域CGRP表达发生改变。加力3d时，根尖牙周膜CGRP表达稍增加；加力7d时，所有观察区域牙周膜内CGRP表达显著增加。结论：CGRP在正畸牙移动过程中组织重建的多个阶段起作用，参与了牙周膜早期的重建和晚期的再生。     

Reduction of orthodontic tooth movement by experimentally induced periodontal inflammation in mice

Orthodontic therapy is known to have an aggravating effect on the progression of destructive periodontitis if oral hygiene is not maintained. However, it is largely unknown how active periodontitis affects the velocity of orthodontic tooth movement. In this study, we examined the effect of periodontal inflammation on orthodontic tooth movement using a mouse model. Orthodontic force was applied on the maxillary first molar of mice, with or without ligature wire to induce experimental periodontitis. The distance moved by the first molar was significantly reduced by the ligature-induced experimental periodontitis. Tartrate-resistant acid phosphatase staining revealed that the number of osteoclasts present during orthodontic treatment was lower in the pressure zone of alveolar bone in the presence of periodontal inflammation. Consistently, the expression level of receptor activator of nuclear factor-κB ligand (RANKL) in the pressure zone was decreased in the ligature group. By contrast, experimental periodontitis increased the expression of cyclooxygenase-2 mRNA in the periodontal tissues, while in vitro treatment with prostaglandin E₂ decreased extracellular signal-regulated kinase phosphorylation and RANKL expression induced by mechanical stress in osteoblasts. Taken together, these results suggest that the orthodontic force-induced osteoclastogenesis in alveolar bone was inhibited by the accompanying periodontal inflammation, at least partly through prostaglandin E₂, resulting in reduced orthodontic tooth movement.     

Cone‐Beam Computed Tomography and Interdisciplinary Dentofacial Therapy: An American Academy of Periodontology Best Evidence Review Focusing on Risk Assessment of the Dentoalveolar Bone Changes Influenced by Tooth Movement

Background: The aim of this systematic review is to evaluate whether cone‐beam computed tomography (CBCT) imaging can be used to assess dentoalveolar anatomy critical to the periodontist when determining risk assessment for patients undergoing orthodontic therapy using fixed or removable appliances. Methods: Both observational and interventional trials reporting on the use of CBCT imaging assessing the impact of orthodontic/dentofacial orthopedic treatment on periodontal tissues (i.e., alveolar bone) were included. Changes in the alveolar bone thickness and height around natural teeth as well as treatment costs were evaluated. MEDLINE (via PubMed) and EMBASE databases were searched for articles published in the English language, up to and including July 2016, and extracted data were organized into evidence tables. Results: Thirteen studies were included in this systematic review describing the positive or deleterious changes on the alveolar bone surrounding natural teeth undergoing orthodontic tooth movement or influenced by orthopedic forces through fixed appliances. Clinical recommendation summaries presenting the strengths and weaknesses of the evidence in terms of benefits and harms were generated. Conclusions: CBCT imaging can improve the periodontal diagnostic acumen regarding alveolar bone alterations influenced by orthodontic tooth movement and can help determine risk assessment prior to such intervention. Clinicians are also better informed to determine risk assessment and develop preventative or plan interceptive periodontal augmentation (soft tissue and/or bone augmentation) therapies for patients undergoing orthodontic tooth movement. These considerations are recognized as being especially critical for treatment approaches in patients where buccal tooth movement (expansion) is planned in the anterior mandible or involving the maxillary premolars.     

Experiments to Determine the Material Properties of the Periodontal Ligament

PHYSIOLOGY OF THE PERIODONTAL LIGAMENT: The periodontal ligament is a soft biological tissue that controls tooth movement under physiological loads by joining tooth and alveolar bone. Its various components differ in their material properties. Their spatial configuration and interaction are responsible for the reaction of the tissue in a loading situation. Due to the combination of fluid and elastic elements the periodontal ligament shows a viscoelastic behavior typical of soft biological tissues. It is characterized by non-linearity and time dependency, and additionally depends on loading history. BEHAVIOR UNDER EXTERNAL LOADS: In orthodontics, external loads are applied to the tooth crowns using orthodontic appliances. Since stresses and strains in the periodontal tissue, caused by the initial tooth movement, stimulate alveolar bone remodeling and thus orthodontic tooth movement, knowledge of the material properties of the periodontal ligament is fundamental to selection of an optimal force system for targeted tooth movement. OWN EXPERIMENTS: For this reason, typical properties of the viscoelastic material behavior of the periodontal ligament were tested experimentally in the present study, using samples from pig mandibles. This enabled the properties of force relaxation and hysteresis of this tissue, both of which depend on loading history, to be verified. CONCLUSION: The experimental results allow characterization of the tissue and thus contribute to an understanding of the biomechanics of tooth displacement under externally applied loads.     

增龄因素对鼠正畸牙牙周组织骨保护素及其配体表达的影响

目的:比较幼年鼠和成年鼠在正畸牙移动中牙周组织骨保护素(OPG)及其配体(OPGL)表达的不同比值,探讨增龄因素对正畸骨改建影响的分子机制。方法:制备大鼠正畸牙齿移动模型,于牙齿移动1d、3d、5d、7d、10d、14d及14d后去除正畸力1周后取材,免疫组化检测牙周组织OPG和OPGL的表达。结果:①.牙齿移动3d时,幼年鼠压力侧OPGL的表达明显增强;而成年鼠此时OPGL的表达没有幼年鼠明显。②.牙齿移动5d和7d时,幼年鼠和成年鼠OPGL的表达均成强阳性,破骨细胞多。③.牙齿移动10d、14d时,幼年鼠和成年鼠OPGL的表达逐渐减弱。④.14d时去除正畸力至21d时发现幼年鼠和成年鼠OPGL均已成弱阳性表达,幼年鼠可见部分成骨细胞。结论:在正畸力的作用下,OPGL与OPG的表达比值与年龄关系密切,增龄因素引起的牙周组织内OPGL/OPG表达变化可能是导致成年正畸特点的分子机制之一。     

大鼠正畸牙移动过程中牙周组织内血管活性肠肽的变化

目的：了解大鼠正畸牙移动过程中牙周组织内血管活性肠肽(vasoactive intestinal peptide,VIP)的变化，探讨VIP在正畸牙移动过程中的作用。方法：将40只雄性Wistar大鼠(体重240-280g)随机分为8组，其中一组未加力为对照组。选择右上第一磨牙作为实验牙，制备大鼠正畸牙移动不同时间牙周组织切片，进行免疫组织化学研究。结果：正畸牙移动过程中，牙周组织不同区域VIP表达发生改变。加力12小时，牙周膜VIP表达稍增加；加力14天时，所有观察区域牙周膜内VIP表达显著增加。结论：VIP在正畸牙移动过程中组织重建的多个阶段起作用，参与了牙周膜早期的重建和晚期的再生。     

降钙素基因相关肽对牙正畸移动微环境改建作用的研究进展

降钙素基因相关肽(calcitonin gene related peptide,CGRP)是由神经末梢分泌的一种神经多肽,近年来,因其被发现是神经调控骨改建的关键因子并且与血管及胶原纤维的改建有关而备受关注.牙正畸移动(orthodontic tooth movement,OTM)过程中,局部牙周微环境包括牙槽骨、牙...     

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。     

Effect of p38 MAP kinase on the production of MMP-1 in human gingival fibroblast-like cells

Tooth movement due to orthodontic force application is characterized by remodeling changes in dental and paradental tissues, including dental pulp, periodontal ligaments, alveolar bone, and gingiva. Although gingival changes have been found to be important for the overall response, they have attracted only minimal attention. We therefore focused on gingival changes during tooth movement. Matrix metalloproteinases (MMPs) concentrations are elevated during orthodontic tooth movement and in compression of the periodontal ligament, and are believed to participate in soft tissue remodeling. Furthermore, many kinds of growth factors, including PDGF, are released from periodontal tissue during orthodontic tooth movement. In the present study, we demonstrated that MMP-1 was produced from human gingival fibroblast-like cells (HGFs) in response to PDGF-bb in a p38 MAP kinase-dependent manner. Blocking of p38 MAP kinase activation by the inhibitor SB203580 significantly inhibited PDGF-bb-induced production of MMP-1 without affecting the total production of MMP-2. These results suggest that PDGF-bb facilitates connective tissue remodeling through induction of the production of the collagenase, MMP-1.     

牙槽骨缺损与正畸诊疗研究进展

牙槽骨缺损可不伴有任何临床症状。如果正畸治疗后出现较严重的牙槽骨缺损,会造成牙周组织的病理性变化,累及患者牙周健康,降低正畸疗效的稳定性,同时牙槽骨缺损也会影响牙齿移动的方式和生物力学机制。     

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??The alveolar bone defect may not be associated with any clinical symptoms. If more serious alveolar bone defect occurs after orthodontic treatment?? it will lead pathological changes in periodontal tissue?? involving patients with periodontal health?? reducing the stability of orthodontic efficacy?? and alveolar bone defect also affects the tooth movement information and biomechanical mechanisms.     

正畸力作用下大鼠白细胞介素-6的表达及牙槽骨改建的研究

目的:观察正畸力作用下IL-6在大鼠牙周组织内的表达分布及牙槽骨高度的改变,研究正畸力对牙周组织改建的作用.方法:将30 只SD大鼠随机分为空白对照组和加力组,施加0.49 N近中向正畸力于加力组25 只大鼠的左侧上颌第一磨牙.运用免疫组织化学及组织形态分析法观测各组大鼠上颌第一磨牙加力后0、1、3、5、7、10 d的IL-6表达量及牙槽骨吸收量.结果:加力组大鼠牙周组织内IL-6的表达在受力后第3天达到高峰,之后开始下降;其近中牙槽骨未见明显丧失.结论:正畸力虽可引发局部牙周组织的炎症反应及IL-6等促炎性细胞因子的释放,但具有一定的自限性,不会导致牙周组织的严重破坏和牙槽骨的明显吸收.     

Orthodontic treatment of gingival recession: indications

Gingival recession is a complex phenomenon. Root coverage results can be predictable regarding to the anatomy of the area. This includes the width of keratinized and attached gingiva, the buccolingual dimension of both soft tissue and alveolar bone, and the position and angulation of the teeth. If the tooth is out of the envelope of the alveolar process, with alveolar bone dehiscence and low thickness of the marginal soft tissue, the recession risk is important. Many techniques have been introduced to treat gingival recession. But lots of failures are linked to tooth position. An adequate orthodontic therapy, with controlled tooth movement, can improve periodontal tissues and thus improves the esthetical outcome. In some cases, orthodontic treatment is suggested to lead to an improved periodontal condition without pre-orthodontic gingival augmentation.