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。     

微型种植体支抗压低犬上切牙的牙根表面扫描电镜观察

目的:利用微型种植体作为支抗,建立犬上切牙压低移动的实验动物模型,研究压低移动牙牙根表面结构的变化。方法:9只犬随机分为5组,其中Ⅰ组为对照组,1只犬,未施加牵引力;Ⅱ、Ⅲ、Ⅳ、Ⅴ组每组2只,在上颌两侧第二切牙牙根和第三切牙牙根之间唇侧的牙槽间隔处植入微型种植体作为支抗,每侧施加100g的牵引力,压低上颌两侧第一切牙和第二切牙,分别于加力后1、2、4、12周(主动加力4周,撤力后保持8周)时处死动物,完整拔出实验牙,制作扫描电镜标本,观察其牙根表面形态的变化。结果:Ⅱ组在牙根尖表面可见小的吸收陷窝,较浅,面积局限;Ⅲ组在接近根尖1/3处可见融合的吸收陷窝,未见牙本质暴露;Ⅳ组在根尖1/3与根中1/3交界处可见吸收深达牙本质的陷窝,且面积广泛;Ⅴ组牙根吸收停止,吸收凹陷变浅,底部变平。结论:在持续的压低力作用下,随着施力时间的延长,牙根的吸收由根尖部向牙颈部扩展,且逐渐加重。停止加力后,吸收牙根明显修复。     

牙周膜牵张正畸过程中牙根吸收的研究

牙周膜牵张牙齿快速移动技术是一项快速移动牙齿的新方法 ,能较大幅度地提高牙齿移动的速度[1] 。有关的研究报道目前尚少。本项实验的目的 ,是应用扫描电镜 (SEM )对被牵张牙受压侧牙根的吸收情况进行定量观察。1.实验方法 :成年杂种犬 6只 ,每只犬下颌左右侧分别设为牵张侧和常规加力侧。①牵张侧 :拔除第二前磨牙 ,用齿科裂钻磨除部分第一、二前磨牙牙槽中隔 ,以降低牙槽中隔的阻力。在第一和第三前磨牙上粘接自制的牵张装置 ,每天加力 2次 ,每次 0 2 5mm ;至第 14天 ,停止加力 ,保持至 2 1d。②常规加力侧 :拔牙部位、支抗牙、移动牙…     

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。     

骨皮质切开术辅助上切牙内收后对牙根及牙槽骨影响的锥形束CT研究

目的 探讨骨皮质切开术辅助上切牙内收后对上颌切牙牙根吸收、牙槽骨厚度和牙槽骨高度的影响.方法 招募20例拔除两个上颌第一前磨牙的骨性Ⅱ类1分类错牙合畸形患者,分为骨皮质切开术组(n=10)和对照组(n=10).矫治前后拍摄锥形束CT,测量两组矫治前后上颌切牙牙根长度、牙槽骨厚度和牙槽骨丧失高度.结果 骨皮质切开术组矫治疗程明显小于对照组(P<0.05);骨皮质切开术组和对照组上颌切牙牙根吸收未见明显差异(P>0.05);骨皮质切开术组治疗前后在上颌中切牙和侧切牙根中和根尖水平唇侧牙槽骨厚度的变化量大于对照组(P<0.05);骨皮质切开术组中切牙腭侧牙槽骨丧失高度量大于对照组(P<0.05).结论 骨皮质切开术辅助上切牙内收结合植骨术可以增加切牙区的牙槽骨厚度,但是在内收过程中不能减少牙根吸收,且对腭侧牙槽骨高度有一定损害.     

上颌埋伏阻生前牙正畸治疗的临床研究

目的：观察上颌埋伏阻生前牙应用固定正畸方法进行矫治的临床疗效,探讨埋伏阻生前牙有效的治疗方法。方法：对49例58颗上颌前牙埋伏阻生病例,应用固定正畸进行矫治,结合牙槽外科开窗术,对埋伏牙进行牵引。其中20颗进行开拓间隙使之自然萌出,38颗进行开窗封闭式牵引导萌矫治。结果：55颗阻生牙矫治后牙髓活力正常、未见埋伏牙及邻牙牙根吸收、牙周组织正常。开窗封闭式牵引导萌有3颗牙治疗失败,总体成功率94.8%。结论：应用固定正畸技术开拓间隙或结合牙槽外科开窗术导萌埋伏阻生牙,可有效保存上颌埋伏阻生前牙。     

大鼠正畸牙根吸收早期龈沟液中DPP的变化规律

目的：构建大鼠正畸牙根吸收模型,检测龈沟液中牙本质磷蛋白（DPP）的浓度变化规律。方法：雌性12周龄SD大鼠46只,其中16只取上颌第一磨牙及牙周组织,通过HE和TRAP染色观察不同时间点根吸收程度;另30只随机分为2组,持续加力28 d（CF组）和加力14 d后停止加力（IF组）,收集龈沟液并通过ELISA检测DPP浓度。结果：持续加力14 d,DPP浓度逐渐升高,CF组与IF组间无显著差异（P〉0.05）;第14 d到28 d,CF组DPP浓度逐渐降低,而IF组DPP浓度在第21 d仍升高,组间有显著差异（P〈0.01）。根吸收相对面积和DPP浓度显著相关（P〈0.05）。结论：DPP作为牙的特异性蛋白,与正畸牙根吸收的修复相关,可能是早期诊断正畸牙根吸收的指标。     

骨疏康对大鼠实验性根吸收过程中MMP-2表达影响的研究

目的 初步研究在骨疏康作用下,大鼠正畸牙移动性根吸收过程中MMP-2的表达规律。探讨骨疏康在根吸收发生发展过程中的作用,为正畸临床中牙根吸收的预防和治疗提供理论参考依据。方法 选取60只雄性SD大鼠,随机分为实验组（30只）和对照组（30只）,实验组进行骨疏康制剂灌胃,对照组采用蒸馏水灌胃,给药剂量为 2.1 g/kg体重,于每天早晨灌胃一次。实验组和对照组再分别分为加力0、3、7、14、21、28 d组,每组5只,两组动物都给予0.6 N的力拉上颌右侧第一磨牙近中移动,建立大鼠正畸牙移动性根吸收模型,分别在实验的规定时间处死大鼠,HE染色观察牙根吸收形态学变化,免疫组化观察MMP-2在牙根吸收区的表达情况。结果 两组大鼠不同牙移动时间牙根吸收指数比较发现,随着加力时间的延长,各组牙根吸收指数逐渐增大,根吸收从第三天开始出现,逐渐加重,14 d后根吸收速度减慢,组间相同时间点比较,骨疏康组根吸收程度轻于对照组,除0、3 d组牙根吸收指数无统计学意义（P＞0.05）,其余各组均有统计学差异（P<0.05）。免疫组化结果显示：MMP-2在加力0 d组表达较弱,随着加力时间的延长,MMP-2的阳性细胞数目逐渐增多,对照组和骨疏康组均在7 d时呈强阳性表达,达到高峰,14 d开始逐渐下降,骨疏康组在加力21 d时MMP-2呈弱表达。对照组在加力28 d时MMP-2呈弱表达,趋于正常组织的表达水平。结论 MMP-2是牙根吸收的主要炎性介质之一,参与了根吸收的过程,骨疏康可有效地抑制正畸牙移动根吸收的发生。     

切牙管及其与上颌中切牙位置关系的研究进展

上颌中切牙的矢状向位置决定了正畸患者的侧貌美观,在正畸临床诊疗中,上颌前突患者一般需要通过减数四个前磨牙进行矫治,以最大支抗内收上下颌前牙,来改善侧貌,解决突度问题。传统支抗正畸手段可以使上颌中切牙内收5.78mm,而种植支抗可以使上颌中切牙的最大内收量增大至8mm,但是在上颌前牙内收的过程中,少数上颌中切牙会侵犯上颌骨一个重要的解剖结构——切牙管,从而导致牙根吸收,牙齿松动等并发症的出现。因此本文就切牙管及其与上颌中切牙位置关系的研究进展做一综述。     

螺旋压缩成骨器配合牙槽外科减阻快速内收上颌前牙的有限元分析

目的探讨螺旋压缩成骨器对上颌前牙应力分布及位移的影响。方法构建螺旋压缩成骨器配合牙槽外科减阻快速内收上颌前牙三维有限元模型,在对上前牙加载位移0.50mm和0.75mm两种工况下,分析上颌中切牙、侧切牙、尖牙唇腭侧及近远中应力分布及位移。结果两种工况下切牙颈部唇侧位移最大,腭侧应力最大;尖牙颈部近中位移和应力最大,唇侧位移和应力分布最小,两种工况载荷效果总体趋势相同。结论螺旋压缩成骨器两种工况对前牙内收都有影响,中切牙、侧切牙、尖牙的内收趋势明显,中切牙和尖牙有旋转趋势。     

En masse retraction and two-step retraction of maxillary anterior teeth in adult Class I women. A comparison of anchorage loss

OBJECTIVE: To compare the amount of anchorage loss of the maxillary posterior teeth and amount of retraction of the maxillary anterior teeth between en masse retraction and two-step retraction of the anterior teeth. MATERIALS AND METHODS: The sample consisted of 30 female adult patients with Class I malocclusion and lip protrusion who needed maximum posterior anchorage. The sample was subdivided into group 1 (n = 15, mean age = 21.4 years, en masse retraction) and group 2 (n = 15, mean age = 24.6 years, two-step retraction). Lateral cephalograms were taken before (T1) and after treatment (T2). Nine skeletal and 10 anchorage variables were measured, and independent t-test was used for statistical analysis. RESULTS: Although the amount of horizontal retraction of the maxillary anterior teeth was not different between the two groups, there was mild labial movement of the root apices of the upper incisors in group 2 at T2. There were no significant differences in the degree of anchorage loss of the maxillary posterior teeth between the two groups. Bodily and mesial movements of the upper molars occurred in both groups. Approximately 4 mm of the retraction of the upper incisal edges resulted from 1 mm of anchorage loss in the upper molars in both groups. CONCLUSION: No significant differences existed in the degree of anchorage loss of the upper posterior teeth and the amount of retraction of the upper anterior teeth associated with en masse retraction and two-step retraction of the anterior teeth.     

Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man

This study was designed to investigate human repair and reattachment of principal periodontal fibers in areas of resorption on anchor premolar root surfaces following rapid maxillary expansion. Maxillary first premolar teeth were obtained from patients requiring rapid maxillary expansion. Extraction of the teeth was scheduled after periods of retention varying between 14 and 53 weeks. The roots of the teeth were examined via light microscopy and scanning electron microscopy. Extensive root resorption characterized the buccal surfaces of anchor premolars. Repair of the resorptive defects was found to occur exclusively with cellular cementum. Anchor teeth retained for longer periods, up to the maximum of 53 weeks of retention in this study, generally demonstrated more advanced repair. Topographically, Sharpey fiber holes indicative of principal periodontal fiber insertion were found in repair cementum. However, these depressions were neither numerous nor consistent in their presence and location. In human teeth, periodontal attachment to resorbed and repairing surfaces was shown to be present. SEM studies of histologic sections revealed that periodontal fibers and fiber bundles inserted directly into the repair cellular cementum matrix, irrespective of the site of the lesion on the root.     

牙槽骨压缩减骨技术整体后移犬上颌6颗前牙初探

目的探讨牙槽骨压缩减骨技术整体后移6颗上颌前牙的效果。方法选择成年Beagle犬1只,拔除两侧尖牙。整体铸造前牙带环,第二、三前磨牙带环单独铸造并用连接杆连接,前牙和两侧前磨牙铸造带环间焊接螺旋压缩器制成压缩装置。于上颌6颗前牙根尖区唇、腭侧行骨皮质切开,黏固压缩装置,以两侧第二、三前磨牙为支抗,调整螺旋压缩器以0.5mm/d的速率后移上颌前牙,共压缩10d,压缩前后取上颌牙模,拍摄牙片及头颅侧位片,摄面像及口内像。结果经过10d压缩,上前牙整体后移4.10mm,未见明显倾斜,牙周膜正常,根尖未见吸收;第二、三前磨牙近中移0.90mm;前牙反。结论以牙为支抗进行牙槽骨压缩减骨能够整体后移6颗上前牙,但支抗牙有向近中移动,要想减少支抗牙的移动,必须加强支抗。     

基于计算机辅助设计的个性化舌侧矫治的前牙内收系统的临床研究

目的 评价计算机辅助设计的个性化舌侧前牙内收系统对前牙整体内收过程中转矩控制的效果.方法 选取20例拔除上颌第一双尖牙并且采用个性化舌侧系统进行矫治的正畸病例,采用舌侧牵引延长臂(lever-arm)和腭侧微种植钉整体内收上颌6颗前牙.基于患者的CBCT数据,采用Mimics 10.0和Claytool软件确定舌侧牵引延长臂的长度和微种植钉植入部位,使内收力作用线通过前牙阻抗中心并与(牙合)平面平行.对比内收前后软组织、骨骼和牙齿的相关头影测量值变化.结果 治疗前和内收后的头影测量结果显示,上中切牙切缘至PTV的距离(PTV-U1)和上唇至审美平面距离(LS-E)显著减小(P＜0.001),上中切牙切缘至腭平面垂线距离(PP-U1)无显著性变化(P＞0.05).上颌前牙发生了大部分的整体内收和少量的控制性倾斜移动,软组织侧貌明显改善,同时磨牙未出现明显移位.结论 计算机辅助设计和定位的个性化舌侧内收系统,显著提高了舌侧矫治中前牙转矩的控制精度.     

附件对隐形矫治器内收上前牙影响的三维有限元分析

目的    通过拔除上颌第一前磨牙后前牙内收的隐形矫治三维有限元模型,分析切牙上设置附件对牙齿移动方式的影响。方法    基于1例成年患者颌骨的锥形束CT影像数据,按照切牙上有无附件,构建4组拔除第一前磨牙的上颌隐形矫治模型,分别为切牙无附件组、侧切牙单附件组、中切牙单附件组和双附件组;导入Ansys Workbench三维有限元软件,设置4个上切牙控根压入内收的隐形矫治过程,分析牙列初始位移和附件的应力分布。结果    切牙无附件组及中切牙单附件组均发生4个切牙的舌向倾斜移动,后牙产生不同程度的近中倾斜移动,尖牙近中倾斜伴有伸长;侧切牙单附件组及双附件组切牙呈整体内收压入移动趋势,切牙附件的龈方可观测到压应力集中。结论    隐形矫治内收上前牙时,在侧切牙放置附件有助于切牙整体内收的表达,而中切牙附件对牙移动方式的影响较小。     

Rapid canine retraction and orthodontic treatment with dentoalveolar distraction osteogenesis.

PURPOSE: Duration of treatment is one of the things orthodontic patients complain about most. To shorten treatment time, a new technique of rapid canine retraction through distraction osteogenesis was introduced. The effects of dentoalveolar distraction on the dentofacial structures are presented in this article. MATERIAL: The study sample consisted of 20 maxillary canines in 10 growing or adult subjects (mean age, 16.53 years; range, 13.08-25.67 years). First premolars were extracted, the dentoalveolar distraction surgical procedure performed, and a custom-made intraoral, rigid, tooth-borne distraction device was placed. The canines were moved rapidly into the extraction sites in 8 to 14 days, at a rate of 0.8 mm per day. RESULTS: Full retraction of the canines was achieved in a mean time of 10.05 (+/-2.01) days. The anchorage teeth were able to withstand the retraction forces with minimal anchorage loss. The mean change in canine inclination was 13.15 degrees +/- 4.65 degrees, anterior face height and mandibular plane angle increased, and overjet decreased significantly at the end of dentoalveolar distraction. No clinical and radiographic evidence of complications, such as root fracture, root resorption, ankylosis, periodontal problems, and soft tissue dehiscence, was observed. Patients had minimal to moderate discomfort after the surgery. CONCLUSIONS: The dentoalveolar distraction technique is an innovative method that reduces overall orthodontic treatment time by nearly 50%, with no unfavorable effects on surrounding structures.     

Effects of intrusion combined with anterior retraction on apical root resorption

This study evaluated the influence of intrusion mechanics combined with anterior retraction on root resorption of the maxillary incisors. A sample of 56 patients was divided into two groups: group 1 comprised 28 patients (12 females and 16 males), presenting with an increased overjet and deep overbite (6.48 and 4.78 mm, respectively) treated with reverse curve of Spee intrusion mechanics and group 2 comprised 28 patients (12 females and 16 males) with an increased overjet of 5.67 mm and a normal overbite of 1.12 mm. The initial mean ages for groups 1 and 2 were 13.41 and 13.27 years, respectively. Pre- (T1) and post- (T2) treatment periapical radiographs were used to evaluate root resorption. The groups were compared using the Mann-Whitney U-test. Correlation between root resorption and tooth movement was investigated with Spearman's correlation coefficient. The subjects in group 1 had statistically greater root resorption (P < 0.05) than those in group 2. The initial overbite severity and the amount of correction had significant positive correlations with root resorption (r = 0.324 and r = 0.320, respectively). The combination of anterior retraction with intrusive mechanics causes more root resorption than anterior retraction of the maxillary incisors alone.     

Mini-implants for retraction,intrusion and protraction in a Class II division 1 patient

Abstract

This case report demonstrates the clinical utility and versatility of mini-implants in carrying out different types of tooth movement in a 14-year-old boy with a ‘severe’ Class II division 1 malocclusion. Mini-implants were placed for ‘en masse’ retraction and intrusion of maxillary anterior teeth and for lower molar protraction. More than 11 mm of maxillary incisor retraction was achieved together with 3 mm of intrusion. There was significant reduction in the dentoalveolar protrusion and retraction of the upper lip, which resulted in decreased mentalis strain and improved chin projection. Cephalometric superimposition and panoramic radiographs showed no anchorage loss and good occlusion at the end of treatment.     

Root resorption in human mandibular first premolars after rotation as detected by scanning electron microscopy.

The aims of this study were to investigate the presence, location, and severity of root resorption after orthodontic rotation for different lengths of time. Eighteen mandibular first premolars due to be extracted from 9 patients were intraindividually divided into 2 groups. Eight teeth were not moved (control group), and 10 teeth were rotated (experimental group) with a force of 50 g delivered by elastomeric modules through symmetrical brackets bonded on the buccal and lingual surfaces (25 g buccally and 25 g lingually) for periods of 2, 3, 4, and 6 weeks. The teeth were extracted, fixed, and treated with 2% sodium hypochlorite to remove the organic tissue components and then dehydrated in ethanol, air-dried, coated with gold, and analyzed in a scanning electron microscope. Examination by scanning electron microscopy revealed many concavities (resorption lacunae) on the root surfaces of all rotated teeth. The resorption areas were located mainly at the medial root third, in regions that corresponded to the prominent zones of the roots. The resorption lacunae in the teeth moved for longer time periods were deeper, often affecting the underlying root dentin, and were mainly at the medial root third. Both the apical and cervical thirds were clearly less affected at all the studied intervals. The root surfaces at the nonprominent root zones did not show signs of resorption.