Clinical study of correction of ClassⅡdivision 1 malocclusion with improved mandibular lip bumper in mixed dentition

Objective To evaluate the early treatment effects of improved mandibular lip bumper on patients with Angle Class Ⅱ,Division 1 malocclusion in mixed dentition.Methods According to inclusion criteria of the study,six patients with Angle Class Ⅱ,Division 1 malocclusion in mixed dentition were selected and treated with improved mandibular lip bumper and maxillary removable appliance.Cephalometric analysis was performed before and after treatment.Resuits The improved appliance could stimulate the growth of mandible.After treatment,overjet and molar relationship improved.Conclusions The improved mandibular lip bumper can interrupt lip-biting and is helpful to achieve growth modification in treating Class Ⅱ,Division 1 malocclusion.     

下颌J钩高位牵引配合改良MEAW技术矫治骨性Ⅲ类错■的临床研究

目的:评价下颌J钩高位牵引配合改良多曲方丝弓技术矫治以下颌发育过度为主的安氏Ⅲ类骨性错■的疗效?方法:选取符合纳入标准的7名恒牙期以下颌发育过度为主的骨性Ⅲ类错■患者,行下颌J钩高位牵引结合改良多曲方丝弓技术治疗,对治疗前?上多曲方丝弓前?治疗结束后X线头颅侧位片进行测量分析比较?结果:上前牙在前期排齐整平阶段进一步唇倾代偿;在下颌J钩高位牵引结合多曲方丝使用后,下颌磨牙远中移动及远中竖直明显,下前牙内收明显,上前牙唇倾度未见明显变化,下颌骨向下向后旋转;矫治结束后覆盖及磨牙关系发生了显著变化?结论:应用下颌J钩高位牵引结合改良多曲方丝弓技术矫治恒牙期以下颌发育过度为主的骨性Ⅲ类错■则更有针对性,且切实可行?     

大鼠正畸牙移动过程中牙周组织TrkA的表达变化

目的:了解大鼠正畸牙移动过程中牙周组织内神经生长因子特异性酪氨酸蛋白激酶受体(TrkA)的变化,探讨TrkA在正畸牙移动过程中的作用。方法:将85只体重(200±10)g雄性SD大鼠,随机分为空白对照组、实验加力组和对照不加力组,并各分为6 h、12 h、24 h、3天、5天、7天、14天、21天亚组,每组5只。选择左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HE染色和免疫组织化学研究。结果:正畸牙移动过程中,牙周组织内TrkA表达发生改变。TrkA表达量在正畸模型加载后先轻微下调后上调,实验加力组和对照不加力组分别于第7天、第3天时Trk A表达水平达到最高,所有观察区域牙周膜内TrkA表达显著增加,且实验组明显高于对照组。结论:TrkA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、修复和晚期的改建。     

大鼠正畸牙移动过程中牙周组织NGF的表达变化

目的了解大鼠正畸牙移动过程中牙周组织内神经生长因子(nerve growth factor,NGF)的变化,探讨NGF在正畸牙移动过程中的作用。方法将85只雄性SD大鼠随机分为17组,其中空白对照组(0d组)、实验加力和对照不加力组各6h、12h、24h、3d、5d、7d、14d、21d组。选择左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,牙周组织内NGF表达发生改变。NGF表达量在正畸模型加载后迅速上调,实验组和对照组分别于5d、1d时表达水平达到最高,所有观察区域牙周膜内NGF表达显著增加,且实验组明显高于对照组。结论NGF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。     

局部注射阿仑膦酸钠对大鼠正畸牙移动的影响

目的观察局部注射阿仑膦酸钠对大鼠正畸牙移动及牙周组织的影响。方法32只Wistar大鼠分为对照组和低剂量、中剂量、高剂量三个实验组,使用40g力牵其左侧上颌第一磨牙近中移动,实验中分别将生理盐水、0.02mmol/L、0.1mmol/L、0.5mmol/L的阿仑膦酸钠溶液注射入各组大鼠上颌第一磨牙近中腭侧的粘骨膜下,注射于实验前3d开始,每3天一次,每次50μl。分别在0、1、3、7、14、17、21d时取模法测量大鼠牙移动量。第21天取上颌组织块经固定、脱钙、脱水、包埋后切片,HE染色观察牙周组织变化,TRAP染色观察压力区破骨细胞数、破牙骨质细胞数,比较各组间是否有差异。结果①各实验组大鼠第一磨牙移动距离显著低于对照组,并随药物浓度增高其抑制效果增强。②实验组压力区破骨细胞数和破牙骨质细胞数显著低于对照组。结论局部注射不同浓度阿仑膦酸钠能获得不同的抑制牙齿移动的效果,可应用于临床中作为一种增强支抗的手段。     

6种软组织分析法在骨性Ⅲ类错[牙合]侧貌评价中的比较研究

目的探寻骨性Ⅲ类错[牙合]软组织特征的头影测量敏感指标。方法选择65例正常[牙合]、40例骨性Ⅲ类错[牙合]治疗前后X线头颅侧位片,选择6种唇部软组织侧貌分析法的14个头影测量项目对145个样本进行测量,各测量指标进行多因素逐步判别分析,并对判别结果进行ROC曲线（receiver operating characteristic curve,受试者工作特征曲线）评价,获得判断骨性Ⅲ类错[牙合]软组织侧貌特征的敏感指标。结果多因素逐步判别结果显示,14个测量项目中LLSn FH、UL-B线、Lip-Diff及H角对Ⅲ类错[牙合]侧貌的判断更有意义。进一步研究中,ROC曲线结果显示,在这四个有较好诊断意义的测量项目里,LL-Sn FH更适合诊断凹面型,其AUC值（area under the curve,曲线下面积）为0．970,Lip-Diff及H角更适合评价Ⅲ类错[牙合]侧貌的治疗效果,其AUC值分别为1．000和0．919。此时三者的灵敏度和特异度都较高。结论Lip-Diff是骨性Ⅲ类错[牙合]侧貌评价的一个较理想的指标,相对于其他传统侧貌测量参考线,能兼顾到较好的诊断能力和评价治疗效果的能力,使用上更加方便直接。     

正畸治疗对骨性Ⅲ类错（he）畸形患者颅面形态的影响

骨性Ⅲ类错（he）畸形的矫治是正畸医生面临的较为棘手的问题,其矫治方法在正畸界也存在较多的争议。骨性Ⅲ类错（he）畸形治疗的手段多种多样,治疗时机的把握相对灵活,治疗的效果也不尽相同。究其原因,在于患者的病因多种多样,其生长发育独具特点。然而,不同的治疗方法对拥有这类错（he）畸形的患者又有着不同的影响。本文就近几十年来各种正畸治疗方法对骨性Ⅲ类错（he）畸形患者颅面形态发育的影响作一综述。     

正畸治疗对骨性Ⅲ类错畸形患者颅面形态的影响

骨性Ⅲ类错(牙合)畸形的矫治是正畸医生面临的较为棘手的问题,其矫治方法在正畸界也存在较多的争议.骨性Ⅲ类错(牙合)畸形治疗的手段多种多样,治疗时机的把握相对灵活,治疗的效果也不尽相同.究其原因,在于患者的病因多种多样,其生长发育独具特点.然而,不同的治疗方法对拥有这类错(牙合)畸形的患者又有着不同的影响.本文就近几十年来各种正畸治疗方法对骨性Ⅲ类错(牙合)畸形患者颅面形态发育的影响作一综述.     

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常规的正畸治疗会增大牙根吸收的风险,许多学者都在自己的临床观察中证实了这个现象的存在。Phillips[1]认为,在多数情况下,牙根吸收在临床上的表现并不明显,对于牙列的功能和寿命都没有影响。然而,在对牙齿进行长期观察之后发现,牙根有再吸收的现象出现,其冠根比     

Apical root resorption in maxillary incisors when employing micro-implant and J-hook headgear anchorage: A 4-month radiographic study

This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage.The prospective randomised clinical trial was conducted in Orthodontic Clinic,College of Stomatology,China from 2008-2009.Subjects are patients requiring fixed appliances on waiting list (n=20).In female Han Chinese patients aged from 16-26 years,standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group,and from 10 similar patients comprising the J-hook headgear group,were assessed for maxillary central incisor apical root resorption.Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances.Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups.Data analysis employed t-tests and the Pearson correlation test,with α=0.05 for statistical significance.The results showed that when compared with the J-hook group,significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference,95% CI=0.70-1.84,P<0.001),which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001).We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed.The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.