The effect of pregnancy on orthodontic tooth movement in rats

Introduction: The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats. Material and Methods: Forty eight female three-month old Wistar rats with an average weight of 250±25 gr were selected and randomly divided into two experimental (pregnant) and control groups (non-pregnant). Maxillary central incisors were tipped distally by insertion of springs exerting 30g force. Two, seven and fourteen days after spring insertion animals were sacrificed. Then the mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement, and the number of osteoclasts were analyzed by independent sample t-test. Results: The results indicated that 2,7 and 14 days after force application there was no significant difference in orthodontic tooth movement between experimental and control groups (p>0.05). The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion (p<0.05). Conclusion: Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant. The number of osteoclasts is significantly decreased during pregnancy. Key words:Pregnancy, rat, orthodontic tooth movement, osteoclast.     

正畸牙齿移动过程中iNOS的表达及意义

目的:观察诱导型一氧化氮合酶(induc ib le n itric oxide synthase,iNOS)在大鼠正畸牙齿移动引发牙周组织改建过程中的表达,探讨NO/iNOS在正畸牙齿移动中的作用机制。方法:56只雄性SD大鼠随机分为8组。分别在正畸加力1,3,5,7,14,21,28 d后进行免疫组化染色和图像分析。结果:正畸加力3 d后,牙周组织细胞iNOS表达增强,7 d iNOS表达达到高峰(P<0.01),以后iNOS表达下降。结论:NO/iNOS参与了正畸牙周组织改建过程。     

正畸牙齿移动过程中内皮素的表达

目的:观察内皮素在大鼠正畸牙齿移动过程中牙周组织改建过程中的表达,探讨内皮素在正畸牙齿移动中的作用机制。方法:64只雄性SD大鼠随机分为8组。正畸加力1、3、5、7、14、21、28d组和对照组,牙周组织分别进行免疫组化染色、图像分析。结果:牙齿移动1d后内皮素表达开始增强,5d达到高峰(P<0.01),以后表达降低。结论:内皮素参与了正畸牙周组织改建过程。     

The effects of samarium-cobalt magnets and pulsed electromagnetic fields on tooth movement

The purpose of this study was to determine whether the application of either samarium cobalt magnets or pulsed electromagnetic fields could increase the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the effect of a magnetic field on bony physiology and metabolism and to monitor for possible systemic side effects. Fifteen grams of laterally directed orthodontic force were applied to move the maxillary central incisors of a sample of 18 young male Hartley guinea pigs divided into three groups: group 1, an orthodontic coil spring was used to move the incisors; group 2, a pair of samarium-cobalt magnets provided the tooth moving force; and group 3, a coil spring was used in combination with a pulsed electromagnetic field. The results showed that both the static magnetic field produced by the samarium-cobalt magnets and the pulsed electromagnetic field used in combination with the coil spring were successful in increasing the rate of tooth movement over that produced by the coil springs alone. The mechanism producing this effect appears to have involved a reduction in the “lag” phase often seen in orthodontic tooth movement. Both magnetically stimulated groups also showed increases in both the organization and amount of new bone deposited in the area of tension between the orthodontically moved maxillary incisors. (AM J ORTHOD DENTOFAC ORTHOP 1995;107:578-88.)     

低强度脉冲超声促进大鼠正畸性牙根吸收的修复

目的 研究低强度脉冲超声(low-intensity pulsed ultrasound,LIPUS)对大鼠正畸性牙根吸收的作用.方法 158只Wistar大鼠建立正畸牙移动根吸收的动物模型,100 g初始力值加载于大鼠右侧上颌两中切牙与第一磨牙之间14 d,随机分为空白对照组、加力组、100 MW/cm2超声治疗组和...     

正畸力作用下大鼠牙周组织中骨桥蛋白的表达

目的：观察SD大鼠正畸牙齿移动过程中牙周组织内骨桥蛋白（osteopontin,OPN）的表达,探讨OPN在正畸牙齿移动过程及成骨方面的作用和机制。方法：选用6～8周龄雄性SD大鼠40只,以左侧上颌第一磨牙为实验组,右侧上颌第一磨牙不加力为对照组,通过自制的加力装置牵引移动大鼠的磨牙,分别在加力后8h、24h、3d、7d处死实验动物,即刻取上颌骨制备组织标本,通过免疫组织化学方法检测SD大鼠牙周组织中OPN的表达。结果：实验组大鼠牙周膜中张力侧OPN表达明显高于对照组,3d、7d组差异有统计学意义（P〈0.01）。结论：在正畸治疗牙齿移动过程中,OPN参与牙周组织的改建并与新骨的形成相关。     

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 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.     

Comparison of the effects of three surgical techniques on the rate of orthodontic tooth movement in a rat model

Objective:To evaluate the effect of corticotomy and corticision, with and without a full mucoperiosteal flap, on the rate of tooth movement and alveolar response in a rat model.Materials and Methods:Sixty male, 6-week-old Wistar rats were divided into five groups based on surgical procedure, as follows: control (no tooth movement), orthodontic tooth movement (OTM) only, corticotomy, corticision, and corticision with full mucoperiosteal flap (corticision + flap). A force of 10–15g was applied from the maxillary left first molar to the maxillary incisors using nickel-titanium springs. Surgery was performed at the time of appliance placement (day 0), and tooth movement occurred for 21 days. Micro–computed tomography was performed on day 21 to evaluate the amount of tooth movement and alveolar bone parameters. Histomorphometry, including tartrate-resistant acid phosphatase staining, was performed to quantify the osteoclast parameters at day 21.Results:No statistical differences in the amount of OTM, bone volume fraction, and tissue density and the osteoclast parameters were found among all experimental groups.Conclusions:Corticotomy and corticision, with or without a full mucoperiosteal flap, did not show a significant effect on either the OTM magnitude or alveolar bone response.     

Effects of short- and long-term celecoxib on orthodontic tooth movement

OBJECTIVE: To test the hypothesis that short- and long-term celecoxib administration has no effect on orthodontic tooth movement. MATERIALS AND METHODS: Male Wistar rats were submitted to short- (3 days) and long-term (14 days) celecoxib administration, while the respective control groups received equivolumetric saline intraperitoneal injections. The upper left first molars of all rats were moved mesially for 14 days by a fixed orthodontic appliance exerting 50 g force upon insertion. After the experimental period, tooth movement was quantified and tissues around the first molar were processed for tartrate-resistant acid phosphatase (TRAP) histochemistry. The amount of tooth movement and the number of TRAP-positive cells on the alveolar bone surface were evaluated. RESULTS: The amount of tooth movement was significantly reduced in rats submitted to short- and long-term celecoxib administration, while the number of osteoclasts on the alveolar bone did not differ between the four groups studied. CONCLUSIONS: The hypothesis is rejected. Although celecoxib administration did not affect the number of osteoclasts, the osteoclast activity might be reduced, which could explain the inhibition of tooth movement observed in the celecoxib-treated animals. These results indicate that orthodontists should be aware of patients under short- and long-term therapy with celecoxib.     

核因子-κB受体活化因子配体在大鼠正畸牙压力侧牙周组织中的表达

目的：探讨正畸牙移动中，压力侧牙周组织中核因子-κB受体活化因子配体(RANKL)的表达在破骨细胞诱导和骨改建中的作用。方法：建立大鼠正畸牙移动模型，对压力侧牙周组织中RANKL蛋白的表达及破骨细胞的生成进行检测。结果：TRAP( )破骨细胞在牙移动第3、5和7天时数量明显增多；免疫组化检测显示牙周成骨细胞、骨衬里细胞、牙周纤维细胞和位于骨陷窝内的破骨细胞，是表达RANKL的主要细胞。与对照组RANKL持续弱阳性表达比较，实验组RANKL在正畸牙移动第3、5和7天时出现强阳性表达，其表达变化与破骨细胞的数量变化较为一致。结论：在大鼠正畸牙移动中，RANKL可能在压力侧牙周组织破骨细胞的形成和骨改建中发挥了重要作用。     

Effect of a static magnetic field on orthodontic tooth movement in the rat

Orthodontic tooth movement may be enhanced by the application of a magnetic field. Bone remodelling necessary for orthodontic tooth movement involves clastic cells, which are tartrate-resistant acid phosphatase (TRAP) positive and which may also be regulated by growth hormone (GH) via its receptor (GHR). The aim of this study was to determine the effect of a static magnetic field (SMF) on orthodontic tooth movement in the rat. Thirty-two male Wistar rats, 9 weeks old, were fitted with an orthodontic appliance directing a mesial force of 30 g on the left maxillary first molar. The appliance incorporated a weight (NM) or a magnet (M). The animals were killed at 1, 3, 7, or 14 days post-appliance insertion, and the maxillae processed to paraffin. Sagittal sections of the first molar were stained with haematoxylin and eosin (H&E), for TRAP activity or immunohistochemically for GHR. The percentage body weight loss/gain, magnetic flux density, tooth movement, width of the periodontal ligament (PDL), length of root resorption lacunae, and hyalinized zone were measured. TRAP and GHR-positive cells along the alveolar bone, root surface, and in the PDL space were counted. The incorporation of a SMF (100-170 Gauss) into an orthodontic appliance did not enhance tooth movement, nor greatly alter the histological appearance of the PDL during tooth movement. However significantly greater root resorption (P = 0.016), increased width of the PDL (P = 0.017) and greater TRAP activity (P = 0.001) were observed for group M at day 7 on the compression side. At day 14 no differences were observed between the appliance groups.     

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.     

Orthodontic tooth movement in cholestatic and cirrhotic rats

OBJECTIVE: To investigate whether cirrhosis and cholestasis could influence orthodontic tooth movement. DESIGN: Basic science, animal experimental study. SETTING: This study was conducted in the Department of Pharmacology, School of Medicine at Tehran University of Medical Sciences in 2007. PARTICIPANTS: A total of 40 male Sprague-Dawley rats (150-200 g) were divided into five experimental groups: non-operated, cholestatic-sham, cirrhotic-sham, cholestatic and cirrhotic groups. METHODS: An orthodontic appliance, consisting of a 5 mm nickel titanium closed coil spring, was ligated between the maxillary right incisor and first molar of each rat to deliver an initial force of 60 g. The cholestatic and cirrhotic groups underwent a bile duct ligation operation and received an orthodontic appliance for 7 days (cholestatic group) and 28 days (cirrhotic group) after surgery. Two other groups underwent a sham operation and had an orthodontic appliance inserted after 7 (cholestatic-sham) and 28 days (cirrhotic-sham). A fifth control group underwent neither bile duct ligation operation nor sham operation. RESULTS: The cirrhotic group showed significantly increased orthodontic tooth movement (OTM), compared to all other study groups (P<0.001). The mean OTM in the cholestatic group was significantly higher than in the other three groups (two sham groups and unoperated one) (P<0.01). Bone density was also significantly decreased in the bile duct ligated (cirrhotic and cholestatic) groups (P<0.01). CONCLUSION: Our data demonstrated that biliary cirrhosis could cause a significant increase in the OTM and decrease in the bone density in rats, though there was no significant alteration in bone resorption or osteoclasts detected in such animals.     

大鼠正畸牙移动中HIF-1_α的表达

目的：探讨正畸牙齿移动过程中牙周组织内低氧诱导因子（hypoxia inducible factor,HIF）-1α的表达变化及作用。方法：将45只雄性SD大鼠随机分为9组,每组5只,分别为：实验加力0、3、6、12、24h和3、5、7、14d组。选择左上第一磨牙作为实验牙,右上颌第一磨牙不加力设为自身对照。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,牙周组织内HIF-1α表达发生改变。HIF-1α表达量在正畸模型加载后迅速上调,实验组于5d、对照组于1d时表达水平达到最高,所有观察区域牙周膜内HIF-1α表达显著增加,且实验组高于对照组。结论：HIF-1α在正畸牙移动过程中牙周组织改建的多个阶段起作用,参与了牙周膜早期的炎症反应及修复和晚期的改建。     

Expression of heat shock protein 47 in the periodontal ligament during orthodontic tooth movement

The aim of this study was to investigate the kinetics of heat shock protein 47 (HSP47) and proliferating cell nuclear antigen (PCNA) immunohistochemistry in periodontal ligament (PDL) cells during orthodontic tooth movement in a mouse model. An orthodontic appliance was set between the upper incisors and the upper left first molar. The mice were killed 2, 6 and 10 days after initiation of orthodontic tooth movement. Computer-assisted image analysis was used to compare the quantitative expression of HSP47 in the PDL. HSP47 expression was significantly higher on the tension side 2 days after application of the appliance, whereas no significant change was observed on the pressure side at any time point. Furthermore, the PCNA labelling indices of PDL cells were increased significantly on the tension side 6 and 10 days after application of the appliance, and on the pressure side 2, 6 and 10 days after application of the appliance. These data suggest that collagen is metabolised predominantly on the tension side, and that PDL cells actively proliferate on both the tension and pressure sides during orthodontic tooth movement.     

正畸牙移动与月经周期关系的实验研究

目的:探讨月经周期不同阶段加力正畸牙移动速度的差异及正畸治疗对月经周期的影响。方法:建立在Wistar雌性大鼠动情周期不同阶段给予正畸加力的实验模型,测量记录相应的牙移动距离差异,放射免疫法测定不同阶段血清中雌二醇的含量变化。采用SPSS11．0软件包,以单因素方差分析法比较动情周期同一阶段加力实验组与对照组的差异,以Student-Newman-Keuls(S-N-K)法进行同一组内动情周期不同阶段各亚组间的两两比较,同时采用余弦节律分析法进行血清雌激素含量变化节律的时间生物学分析。结果:大鼠动情周期不同阶段血清雌二醇含量存在近5天的节律变化,其中在动情期最低(P<0．05),此时加力牙移动速度最快(P<0．05),移动距离为(2．10±0．14)mm;在动情前期最高(P<0．05),牙移动最慢(P<0．05),移动距离为(1.79+0．03)mm。正畸加力使大鼠血清雌二醇浓度升高,但未改变其节律性波动的变化规律。结论:女性正畸患者可能存在一个牙移动最快的最佳加力时机,在雌激素水平最低的月经来潮前给予正畸加力,可能会获得最快的牙移动效果。     

HSP70在大鼠牙移动过程中的表达及其生物学意义

目的:研究大鼠磨牙移动过程中诱导型热休克蛋白70(HSP70)在牙周组织中的动态表达特点,推测其在牙周组织改建中的生物学意义。方法:建立大鼠牙移动的动物模型,采用免疫组织化学方法观察大鼠磨牙移动1、3、5、7、14d内诱导型HSP70在牙周组织中的动态表达及定位情况。结果:HSP70的表达在牙周膜受力早期呈强阳性,随后表达逐渐减弱,至14d为弱阳性;同一时期牙周膜的张力侧和压力侧诱导型HSP70的表达存在差异。结论:HSP70在大鼠磨牙受外力移动过程中呈现由强到弱的动态变化及区域性变化,这可能与牙周组织损伤的应激保护和改建过程中蛋白合成的需要有关。     

张力作用下牙周组织破骨细胞分化因子、破骨细胞发生抑制因子表达变化的研究

目的:运用原位杂交的方法,观察破骨细胞分化因子(ODF)、破骨细胞发生抑制因子(OCIF)在正畸大鼠牙周组织改建过程中张力侧的表达变化,探讨ODF、OCIF与正畸牙周组织改建的关系。方法:8周龄成年健康雄性SD大鼠30只,随机分为对照组、牙齿移动1d组、3d组、5d组、7d组,共5组,每组6只。在大鼠上颌右侧第一磨牙与上颌切牙之间安置正畸矫治器装置,施力50g。在相应时间段处死实验动物,取材固定,进行原位杂交染色、图像分析。结果:在牙齿移动3d后,OCIF原位杂交染色在张力侧逐渐深染,OCIF mR-NA阳性细胞数量逐渐增多,OCIF阳性表达在5d时达到最高,并可见到有新骨形成;7d时OCIF阳性表达及分布情况与3d时相类似。张力侧牙周膜细胞、成骨细胞的ODF原位杂交染色阳性反应随天数的增加有逐渐增强趋势,并可观察到有ODFmRNA阳性破骨细胞出现,但表达变化并不明显。结论:ODF及OCIF参与了正畸牙周组织改建过程,OCIFmRNA在张力区随正畸牙齿移动表达升高具有时间依赖性。     

The role of opioid systems on orthodontic tooth movement in cholestatic rats

Endogenous opioids have been reported to accumulate in the plasma of cholestatic subjects. Another report showed that human osteoblast-like cells, MG-63, express 3 types of opioid receptors. In our laboratory we noticed that orthodontic tooth movement (OTM) is enhanced in cholestatic rats. Therefore, we suggest a possible role of opioid systems in bone remodeling and raising the rate of OTM in cholestatic conditions. To investigate this hypothesis, rat models were established and divided into 5 study groups. An orthodontic appliance, consisting of a 5 mm nickel-titanium closed coil spring, was ligated between the maxillary right incisor and first molar of each rat to deliver an initial force of 60 g. The bile duct ligated (BDL) group underwent a bile duct ligation operation and received orthodontic appliance 7 days after surgery. Another group underwent a sham operation and orthodontic appliances were inserted just as in the BDL group protocol. Surgery was performed the BDL + naltrexone group and orthodontic appliances were inserted 7 days after surgery. This group received daily subcutaneous injections of naltrexone HCI (an opioid antagonist) at 20 mg/kg at 24-hour intervals from the day of force application until the end of the study period. Another group, the naltrexone group, received naltrexone injections like the BDL + naltrexone group. A fifth control group neither underwent surgery nor received injections. Orthodontic tooth movement was measured 14 days after appliance insertion. The bile duct ligated group showed significantly increased OTM compared to all other study groups (P < .001). The difference between the OTM in the BDL + naltrexone and control groups was insignificant. This study suggests a role for opioid systems in OTM in cholestasis conditions.