Later orthodontic appliance reactivation stimulates immediate appearance of osteoclasts and linear tooth movement

Background: Delays in the appearance of osteoclasts at compression sites occur after orthodontic appliance reactivation, when this is done during both the period of osteoclast recruitment and the peak expansion in the osteoclast population. This experiment examines osteoclasts and tooth movement in alveolar bone after appliance reactivation coinciding with alveolar bone formation and the time when reactivation osteoclasts first appear (ie, 10 days after initial appliance activation). Methods: Bilateral orthodontic appliances were activated to mesially tip maxillary molars with 40 cN in 144 rats. After 10 days, all rats were randomized into two groups of 72. Group I had appliances reactivated in precisely the same manner as the first activation. Group II had appliances sham-reactivated. Nine to 12 rats were then sacrificed at 1, 3, 5, 7, 10, and 14 days in both groups (eg, day 1 represents an interval of 11 days after the first appliance activation and 1 day after either sham or real reactivation). Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically. Results: Teeth in the reactivated group (Group I) displayed linear tooth movement (62.6 μm/day), and 0.9 mm tooth movement by day 10. Significant increases in osteoclast numbers, osteoclast surface percentage, and surface per individual osteoclast were evident in these animals by 1 day postreactivation (P < .01). Significant treatment-related increases in root resorption were not evident at compression sites at any time. Conclusions: These findings indicate that, after appliance reactivation during the time when reactivation osteoclasts appear, a second cohort of osteoclasts can be recruited immediately, along with immediate and substantial tooth movement and no greater risk of root resorption. (Am J Orthod Dentofacial Orthop 1998;114:692-7)     

Effect of continuous versus intermittent orthodontic forces on root resorption: A microcomputed tomography study

Objectives:To compare the extent of root resorption and the amount of tooth movement between continuous orthodontic force and intermittent orthodontic force that was activated in a similar way to a 4-week orthodontic adjustment period.Materials and Methods:Twenty-five patients who required the extraction of upper first premolars were recruited in this study. A buccally directed continuous force of 150 g was applied to the upper first premolar on one side for 15 weeks. A buccally directed intermittent force (28 days on, 7 days off) of the same magnitude was applied to the contralateral first premolar. The teeth were extracted at the end of the experimental period and processed for volumetric evaluations of resorption craters. The degree of tooth movement and rotation were measured on the study models.Results:Continuous force application displayed significantly higher root resorption volume than the intermittent force application (P < .05), particularly on the buccal and lingual surfaces (P < .05) and the middle third of the root (P < .01). There was more tipping and rotational movement in the continuous force group.Conclusions:In a 4-week orthodontic adjustment period, intermittent force significantly reduced the amount of root resorption compared with continuous force. Although there was less degree of tooth movement with intermittent force, unwanted rotational movement was avoided. This is crucial in patients who are predisposed to orthodontically induced inflammatory root resorption, and the use of this intermittent regimen should be considered.     

Effect of appliance reactivation after decay of initial activation on osteoclasts, tooth movement, and root resorption

Clinical orthodontists frequently reactivate appliances following decay. Studies of tooth movement and tissue responses following reactivations indicate that linear tooth movement and rapid recruitment of osteoclasts can be achieved if reactivation is timed to coincide with the latter part of the bone remodeling cycle initiated by the first activation. Both can be delayed if reactivations are timed for the early part of the previous cycle. The objective of this study was to examine tooth movement, root resorption, and osteoclast recruitment following appliance reactivation after the first activation had decayed. Bilateral orthodontic appliances were activated with 40 cN in 144 rats to mesially tip the maxillary molars. After 16 days, rats were randomized into two groups of 72. In group 1, appliances were reactivated in precisely the same manner as the first activation. In group 2, appliances were sham-reactivated. Rats were sacrificed at 1, 3, 5, 7, 10, and 14 days. Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically; tartrate-resistant acid phosphatase (TRAP) was measured in alveolar bone and serum biochemically. Orthodontic tooth movement was linear in group 1, but osteoclasts required 3 to 5 days to appear. There were no group- or time-related differences in root resorption. Bone TRAP levels were elevated in both groups but dropped significantly (p<0.01) in group 2 at day 7. Appliance reactivations that followed decay of the first activation produced efficient tooth movement without increased risk of root resorption, but these changes were not accompanied by rapid osteoclast recruitment at compression sites. Timing appliance reactivations for the latter portion of the previous bone remodeling cycle could have significant clinical advantages because the delay period seen in tooth movement following a single activation or short-term reactivation can be avoided.     

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.     

Influences of ovariectomy on experimental tooth movement in the rat

Estrogen withdrawal, which is important in the pathogenesis of post-menopausal osteoporosis, accelerates bone metabolism with a negative calcium balance. Therefore, it is hypothesized that estrogen deficiency could affect the rate of experimental tooth movement and alveolar bone remodeling. Six-week-old rats received a bilateral ovariectomy (OVX) or sham operation. Fourteen days later, rats were subjected to lateral tooth movement in the upper molar with nickel-titanium wire of 10 g of force. OVX significantly increased the rate of experimental tooth movement from 12 days after experimental tooth movement (p < 0.001). Eighteen days after the start of tooth movement, bone histomorphometry demonstrated that OVX significantly elevated the osteoblast surface, osteoclast surface, and number of osteoclasts (p < 0.05) in the alveolar bone. These findings indicated that estrogen deficiency caused significantly rapid orthodontic tooth movement, and that the acceleration of tooth movement could be due to the further activation of alveolar bone turnover.     

Incidence and severity of root resorption in orthodontically moved premolars in dogs

OBJECTIVES: To study treatment-related factors for external root resorption during orthodontic tooth movement. DESIGN: An experimental animal study. SETTING AND SAMPLE POPULATION: Department of Orthodontics and Oral Biology, University Medical Centre Nijmegen, The Netherlands. Twenty-four young adult beagle dogs. EXPERIMENTAL VARIABLE: Mandibular premolars were bodily moved with continuous or intermittent controlled orthodontic forces of 10, 25, 50, 100, or 200 cN according to standardized protocols. At different points in time histomorphometry was performed to determine the severity of root resorption. OUTCOME MEASURE: Prevalence of root resorptions, defined as microscopically visible resorption lacunae in the dentin. Severity of resorption was defined by the length, relative length, depth, and surface area of each resorption area. RESULTS: The incidence of root resorption increased with the duration of force application. After 14-17 weeks of force application root resorption was found at 94% of the root surfaces at pressure sides. The effect of force magnitude on the severity of root resorption was not statistically significant. The severity of root resorption was highly related to the force regimen. Continuous forces caused significantly more severe root resorption than intermittent forces. A strong correlation (0.60 < r < 0.68) was found between the amount of tooth movement and the severity of root resorption. CONCLUSIONS: Root resorption increases with the duration of force application. The more teeth are displaced, the more root resorption will occur. Intermittent forces cause less severe root resorption than continuous forces, and force magnitude is probably not decisive for root resorption.     

伊班膦酸钠对正畸源性牙根吸收面积的影响

目的:通过牙齿移动距离的差异、牙周组织中破牙骨质细胞数量的变化及牙根吸收面积的差异,研究伊班膦酸钠对大鼠正畸源性牙根吸收的作用。方法:48只SPF级雌性Wistar大鼠,建立正畸牙齿移动动物模型,设置自身对照,对照侧为对侧未注药侧。在大鼠上颌双侧第一磨牙与上切牙之间安置一0.012英寸镍钛拉簧,施力60 g左右,所有大鼠均于安装矫治器前3 d在实验侧(大鼠上颌左侧)移动牙齿近中腭侧黏骨膜下局部注射50μL伊班膦酸钠,对照侧(大鼠上颌右侧)注射50μL 0.9%氯化钠液。每3 d注射一次直至实验结束。实验第3、7、14 d随机选择8只大鼠处死。分离大鼠头颅骨,用游标卡尺(精确度0.02 mm)测量上颌双侧第一磨牙移动的距离,并制备大鼠第一磨牙及其牙周组织切片,HE染色观察两侧牙周组织形态学变化,观察破牙骨质细胞的数量,采用图像处理软件对两侧的牙根吸收指数进行分析。结果:①牙齿移动距离随实验时间延长逐渐增加,组间比较:实验第3 d,实验侧和对照侧的牙齿移动距离平均值差异无统计学意义;实验第7 d和14 d,实验侧的牙齿移动距离均小于对照侧,差异具有统计学意义(P<0.05)。②实验侧第3 d、7 d和14 d大鼠第一磨牙牙周组织压力侧破牙骨质细胞数量均小于对照侧,且第7 d和14 d结果差异具有统计学意义(P<0.05)。③实验侧第3 d、7 d和14 d大鼠牙根吸收指数均小于对照侧,牙根吸收程度均比对照侧轻,且第7 d和14 d结果差异具有统计学意义(P<0.05)。结论:局部应用伊班膦酸钠可以减缓正畸牙齿移动的速度,减少牙周组织压力侧破牙骨质细胞的数量,减少正畸源性牙根吸收的发生。     

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。     

帕米膦酸钠对大鼠正畸源性根吸收及牙移动影响的研究

目的 研究帕米膦酸钠对大鼠正畸源性根吸收及牙移动的作用。 方法 选取48只6周龄SPF级Wistar雌性大鼠建立正畸牙移动模型,每只大鼠上颌分实验侧和对照侧,实验侧在大鼠左侧第一磨牙近中腭侧黏骨膜下注射0.5 mmol/L帕米膦酸钠50 μl,对照侧注射0.9%生理盐水50 μl,每3天注射1次。分别于实验第3、7、14天时分批处死16只大鼠,随机选择8只测量牙移动距离并制作牙周组织学切片进行牙根吸收指数的测定,另外8只用扫描电镜观察牙根吸收情况。实验数据用PASW statistics18软件进行处理。 结果 实验侧与对照侧牙移动的距离均随着时间的延续逐渐增加,第3、7、14天时实验侧第一磨牙移动距离均小于对照侧,第7、14天时两者差异有统计学意义（P＜0.05）;组织学切片观察牙根吸收指数及电镜扫描结果都显示在第3、7、14天时实验侧相比对照侧牙根吸收少,在第7、14天时两侧牙根吸收程度的差异有统计学意义（P＜0.05）。 结论 局部注射二膦酸盐帕米膦酸钠能够抑制正畸牙移动过程中的牙根吸收,减缓牙移动的速度。     

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。     

应用Micro-CT研究矫治力对正畸牙齿移动及牙根吸收的影响

目的：了解不同矫治力作用下大鼠牙齿移动距离及牙根吸收情况,探索应用Micro?CT研究正畸牙齿移动过程中矫治力对牙根吸收的影响。方法10周龄健康雄性SD大鼠64只（220~270 g）,分别施以10 g （10 g力组）、30 g力（130 g力组）拉右侧上颌第一磨牙向近中移动建立实验动物模型,以对侧同名牙为对照牙。于加力后第3、7、14、28天处死动物,使用Micro?CT扫描上颌第一磨牙及周围牙槽骨,测量上颌第一磨牙近中移动距离,计算加力28 d上颌第一磨牙近中根的表面凹陷体积,进行统计学分析。结果加力后发生牙齿移动,10 g力组在加力14 d内,牙齿移动量小于30 g力组（P =0.039）,在加力28 d时大于30 g力组（P<0.05）。加力28 d,10 g力组、30 g力组的牙根表面凹陷总体积高于对照组（P=0.004）,30 g力组产生的牙根表面凹陷总体积高于10 g力组（P<0.001）。结论 Micro?CT可以对牙齿移动及牙根吸收进行可靠评价及量化分析。加力后28 d,10 g力组移动量较30 g力组大,相应产生牙根吸收较30 g力组少。     

Long-term orthodontic tooth movement response to short-term force in the rat.

Both the amount of force applied and the duration of the application affect tooth movement. To study the effect of duration, adult male Sprague-Dawley rats were fitted with orthodontic appliances delivering a 40-gm initial mesial tipping force to the maxillary molars. The animals were divided into two longitudinal groups (I: 1 hour and II: 24 hours; N = 15). Sham-treated control (III) and 14 day (IV) continuous cross-sectional force tooth movement data were also included for comparison (72 rats per group). Extraoral cephalometric radiographs were obtained at appliance placement and at 1, 3, 5, 7, 10, & 14 days. Tooth movement was determined with respect to palatal implants. ANOVA indicated significant differences existed over time in each group (p = 0.0001). Continuous force applied for 14 days generated a classic three-part tooth movement curve. Short-term forces were characterized by initial mesial movement, a distal relapse period (d3-d5), and a late mesial movement period (d7-d14). The results suggest short-term forces of 1 and 24 hours initiate remodeling events, which result in tooth movement 7 to 14 days later and that the minimum effective duration of a 40-gm activation is less than 1 hour in this animal model.     

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目的    探讨正畸牙齿移动与肿瘤坏死因子α（TNF-α）表达的关系。方法    2008年9月至2009年1月于大连医科大学基础实验室,选取8周龄雄性SD大鼠18只,体重180～220 g。以大鼠上颌左侧牙弓为实验侧,右侧为对照侧。实验侧以大鼠上颌切牙为支抗牙,0.392 N（40 gf）力拉上颌第一磨牙向近中;对照侧不做任何处理。正畸加力第1、3、5、7、14、21天分别处死3只大鼠,取上颌双侧磨牙及周围组织制备切片,进行苏木素-伊红（HE）染色和抗酒石酸酸性磷酸酶（TRAP）染色,并采用免疫组化SABC法检测TNF-α变化（以第5天实验侧切片为阴性对照）。结果    正畸牙齿移动的骨改建过程中TNF-α水平随时间的增加呈先上升后下降的趋势。正常大鼠牙周组织中偶见TNF-α的表达,阴性对照未见TNF-α的表达。实验侧TNF-α的表达在加力第5天达到峰值,第21天接近对照侧的水平。结论    OC的形成分化和骨吸收的发生密切相关,是引发骨吸收的主要细胞;TNF-α是调控OC的形成和分化的重要因子,在正畸牙齿移动中发挥重要作用。     

Evening primrose oil effects on osteoclasts during tooth movement

This study was conducted to investigate the influence of supplemented evening primrose oil (EPO) on osteoclast expression during experimental tooth movement in rats. Forty-eight 10-week-old male Sprague-Dawley rats were divided into experimental and control groups. Animals in the experiment group were fed a 7.25 g/kg daily dose of EPO orally by gastric intubation for 20 days before orthodontic tooth movement. The animals in the control group received an equivalent volume of distilled water by the same method. On day 21, a 40-g mesial tipping force was applied to the maxillary right first molar of each rat. After loading, six animals in each group were sacrificed on days 0, 3, 7, and 14 with the appliance in situ. On day 3, the number of osteoclasts on the appliance side of the experimental group was significantly increased compared with the control group (P < .05). On day 7, the number of osteoclasts on the non-appliance side of the experimental group was significantly increased compared with the control group (P < .05). This study indicates that oral administration of EPO can increase the number of osteoclasts and may accelerate orthodontic tooth movement.     

核因子-κB受体活化因子配体在大鼠正畸牙压力侧骨改建中的作用

目的：初步探讨在正畸牙移动压力侧核因子-κB受体活化因子配基(receptor activator of nuclearfactor-κB ligand，RANKL)的表达在破骨细胞诱导和骨改建中的调节作用。方法：建立大鼠正畸牙移动模型，利用免疫组化的方法对压力侧RANKL的表达及其变化进行检测；并进一步观察了RANKL对大鼠骨髓破骨细胞形成的影响。结果：正畸牙移动压力侧组化结果显示，RANKL阳性表达位于牙周膜细胞和位于骨陷窝内的破骨细胞中，在正畸牙移动第3、5和7天时呈强阳性表达。体外破骨细胞诱导实验结果显示，在巨噬细胞集落刺激因子(macrophage clone stimulating factor，M-CSF)协同作用下，RANKL呈剂量依赖型诱导TRAP阳性细胞生成。结论：大鼠正畸牙移动中，RANKL在压力侧的表达上调有诱导破骨细胞形成的作用，并导致牙槽骨吸收。     

正畸力对大鼠正畸牙根吸收后早期修复的影响

目的：研究大鼠正畸牙根吸收后加力方式的改变对牙根早期修复的影响。方法：选用65只SD大鼠,建立正畸牙根吸收模型,随机分为三个实验组：停止加力组（SF组）、间歇加力组（IF组）、持续加力组（CF组）,另选5只作为空白对照组（NTC组）。采用HE和TRAP染色法对牙根组织形态进行观察。结果：随着停止加力时间的延长,破牙细胞数量明显减少,修复性牙骨质明显增多;IF组与SF组组间牙根吸收相对面积及修复相对面积无明显差异（P〉0.05）;在停止加力第17d组,IF组的TRAP阳性细胞数目及根吸收相对面积明显小于CF组（P〈0.05）。结论：正畸牙根吸收发生后,改变加力方式可影响牙根早期修复,停止加力或停止加力后再加力可降低牙根吸收程度。     

CMT-3 inhibits orthodontic tooth displacement in the rat

OBJECTIVE: Orthodontic tooth movement requires extensive remodeling of the periodontal ligament (PDL) and the alveolar bone. Osteoclasts resorb bone, allowing teeth to migrate in the direction of the force. Matrix metalloproteinases (MMPs) are able to degrade the extracellular matrix of the periodontal tissues. Chemically modified tetracyclines (CMTs) can inhibit MMPs, but lack antimicrobial activity. We hypothesize that CMT-3 will decrease the rate of orthodontic tooth movement in the rat. DESIGN: Eighteen Wistar rats received a standardized orthodontic appliance at one side of the maxilla. During 14 days, three groups of six rats received a daily dose of 0, 6 or 30mg/kg CMT-3, and tooth displacement was measured. Thereafter, osteoclasts were counted on histological sections using an ED-1 staining. Multi- and mononuclear ED-1-positive cells in the PDL were also counted. In addition, sections were stained for MMP-9. RESULTS: CMT-3 significantly inhibited tooth movement (p=0.03) and also decreased the number of osteoclasts at the compression sides in the 30mg/kg group (p<0.05). Significantly more mono- than multinuclear ED-1-positive cells were present in the PDL, but no significant differences were found between the dosage groups. Osteoclasts in the 30mg/kg group seemed to contain less MMP-9 than in the control. CONCLUSIONS: CMT-3 inhibits tooth movement in the rat, probably by reducing the number of osteoclasts at the compression side. This might be due to induction of apoptosis in activated osteoclasts or reduced osteoclast migration. Reduced MMP activity by CMT-3 might also directly inhibit degradation of the organic bone matrix.     

Expression of cathepsin K mRNA during experimental tooth movement in rat as revealed by in situ hybridization

The expression of cathepsin K. a novel collagenolytic enzyme specifically expressed in osteoclasts, was investigated in the rat maxillary dentoalveolar unit during experimental tooth movement by in situ hybridization histochemistry with a non-radioisotopic cRNA probe for rat cathepsin K. Orthodontic elastics were inserted into the interproximal space between the maxillary first and second molars of 7-week-old male SD rats according to Waldo's method and sections prepared from tissues obtained at 12 hr, 1, 2, 3, 4, 7, and 12 days after orthodontic force application. Cathepsin K mRNA expression was detected in the mono- and multinuclear osteoclasts on the pressure side of the alveolar bone at 12 hr after force application, and the distribution and number of cathepsin K mRNA-positive osteoclasts increased time-dependently on the pressure side. At 3-4 days, a marked increase in cathepsin K mRNA-positive osteoclasts was found not only on the pressure side but also on the tension side of the alveolar bone in response to tooth movement. At 7-12 days, the cathepsin K mRNA-positive osteoclasts on both sides had disappeared. These findings suggest that the recruitment of osteoclasts on the pressure side begins during the initial stage of orthodontic tooth movement and the site-specific early induction of cathepsin K mRNA may cause an imbalance in the relative resorption activities on the pressure and tension side incident to such movement.     

GSK-3β对正畸牙齿移动的影响

目的:观察GSK-3β对正畸牙齿移动距离的影响.方法:分别选30 只野生C57小鼠和20 只GSK-3β基因敲除C57小鼠.野生型和基因敲除型各20 只,正畸加力3、5、7、14 d(5 只/组)后处死,取材固定上颌骨扫描Micro CT测量牙齿移动距离,冰冻切片免疫荧光染色观察破骨情况.野生型10 只腹腔注射LiCl(隔天100 ng/ml)加力3 d,7 d处死后扫描MicroCT.结果:与野生型组同期结果相比,GSK-3β基因敲除小鼠牙齿移动距离降低(P<0.05),压力侧破骨细胞减少(P<0.05);基因敲除组与野生型注射LiCl组牙齿移动距离无统计学差异.结论:GSK-3β可以影响破骨细胞形成从而影响正畸牙齿移动.     

大鼠正畸牙移动压力侧牙槽骨中cath K mRNA表达的研究

目的研究组织蛋白酶K（cathepsin K,cath K）mRNA在大鼠正畸牙移动压力侧牙槽骨中的表达变化及时间分布特点,探讨正畸牙移动中牙周改建的分子生物学机制。方法选用80只6周龄SD雄性大鼠建立正畸牙移动模型,分别在加力后2d、5d、7d、10d和14d处死动物各16只,HE染色观察牙周组织改建的变化,TRAP染色计数压力侧破骨细胞数量;实时定量PCR（real-time quantitative PCR）检测cath K mRNA表达变化及时间分布特点。结果cath K mRNA表达随加力时间的增加而增加,在加力后的第7天开始下降。这与牙周组织形态学的变化以及TRAP染色阳性破骨细胞数目的变化规律相一致。结论在生物机械力的诱导下,cathK参与了正畸牙移动骨改建过程中有机基质的降解,cath K mRNA随正畸加力时间的增加出现规律性变化。