上颌切牙内收前后牙根及牙槽骨的变化

目的 通过锥形束CT（CBCT）测量并分析上颌前突患者上颌切牙内收治疗前后牙根及牙槽骨的变化。方法 选取2014年1月—2015年12月完成的正畸病例37例,其中男性17例,女性20例,平均14.5岁。所有患者拔除上颌双侧第一前磨牙且使用种植钉强支抗内收上颌切牙,通过头影测量获取上颌切牙内收角度、内收量及伸长量,使用NewTom NNT软件对CBCT数据进行多平面重建,调整冠状、轴向与矢状轴,选取通过切缘和根尖的牙齿长轴最长的矢状截面测量上颌切牙内收治疗前后牙根及牙槽骨的变化。结果 上颌前牙内收治疗前后,中切牙内收角度为12.92°±6.43°,内收量为（5.54±2.21） mm,伸长量为（0.60±0.95） mm,牙根吸收长度为（0.81±0.46） mm,牙根吸收率为6.80%±3.60%,切牙内收治疗前后牙根长度变化具有统计学差异（P<0.05）,治疗后唇侧牙槽骨高度降低量为（0.20±0.22）mm,治疗前后差异有统计学意义（P<0.05）。牙根吸收率与上颌中切牙切端的水平向位移及根尖至唇侧皮质骨的距离具有相关性;唇侧牙槽骨高度变化量与上颌切牙内收角度的相关系数为0.354,具有统计学意义（P<0.05）。结论 上颌前突患者代偿性治疗后,上颌切牙产生了明显的牙根吸收,唇侧牙槽骨高度降低。牙齿移动量越大,或超出了牙槽骨的解剖限制和改建限度,容易导致牙根吸收。唇侧牙槽骨高度变化量与切牙内收角度呈负相关。     

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...     

拔牙创愈合对正畸牙移动的影响

目的 比较尖牙在不同愈合期的拔牙区内移动后根尖的吸收情况和牙槽骨高度的变化,为临床上选择拔牙区内正畸牙移动的最佳时机提供参考。方法 选取20例需拔除上颌双侧第一前磨牙矫治的错畸形患者的40颗上颌尖牙为研究对象,在拔除上颌第一前磨牙后1周和12周开始随机牵引上颌不同侧尖牙向远中移动,至尖牙与上颌第二前磨牙接触后,拍摄尖牙的根尖定位片,测量尖牙根尖吸收等级和牙槽骨水平高度。结果 在拔除上颌第一前磨牙后1周和12周移动上颌尖牙,尖牙的根尖吸收情况和牙槽骨水平高度没有统计学差异（P>0.05）。结论 拔牙创的愈合对移动牙齿的根尖吸收和牙槽骨水平高度没有明显影响,可以考虑拔牙后早期移动牙齿。     

微型种植体支抗压低幼犬牙齿的基础研究

目的：探讨微型钛钉种植体作为支抗压低幼犬牙齿是否有效以及对幼犬牙槽骨生长发育是否有影响。方法：选用6只本地雄性幼犬,在每只犬的一侧下颌第二前磨牙（P2）第三前磨牙（P3）颊舌侧龈下10mm处分别植入微型种植体,2周后用链状橡皮圈越过颌面连接双侧的种植钉（皮圈力量为150g）,分别压低P2、P3,每2周加力1次,共8周。对侧下颌骨不种植为对照组。实验前后测量同一条幼犬两侧下颌骨的长度及4个部位的宽带和高度值。结果：实验侧和对照侧在种植前后下颌骨的长度、宽度和高度的生长变化无明显差异（P〈0.05）;幼犬实验侧受力牙齿P2被平均压低1.47mm,P3被平均压低0.98mm。结论：微型钛钉种植体作为支抗可以压低牙齿进行有效移动;微型钛钉种植体作为支抗压低牙齿对幼犬牙槽骨的长度、宽度、和高度发育无显著影响。     

减阻牵张法快速移动牙齿的牙根表面扫描电镜观察

目的观察减阻牵张法快速移动牙齿牙根表面结构的变化。方法选择8只犬,随机分为四组,每组2只,采用自身对照设计,随机以一侧下颌为实验侧,另一侧为对照侧,拔除下颌第二前磨牙,实验侧采用减阻牵张法,对照侧采用传统正畸方法,远移第一前磨牙。分别于加力后1、2、4、12周处死动物,完整拔出移动牙,制作扫描电镜标本,观察其牙根表面形态的变化,并计算其牙根吸收指数。结果实验侧移动牙压力侧牙根1周组即出现了明显的吸收,2周、4周组牙根吸收范围和深度明显加重;对照侧1周组根面吸收不明显,2周、4周组吸收逐渐加重,但与实验侧比较,吸收范围和深度明显较轻;牙根吸收指数以上各组实验侧和对照侧均有显著性差异;12周组实验侧和对照侧根面表现相似,吸收馅窝变浅,根面变平,两侧牙根吸收指数没有显著性差异。结论与传统正畸牙移动方法相比,减阻牵张法快速移动牙齿能加重移动牙压力侧牙根吸收,但停止加力后,随着时间的延长,吸收牙根可逐渐修复。     

应用微型种植体支抗压低犬后牙过程中牙周组织改建的组织学研究

目的:应用微型种植体支抗压低犬第三前磨牙,观察此方法压低牙齿时牙周组织的改建情况,为种植体支抗压低牙齿的正畸临床应用提供理论依据.方法:实验犬6只,在左右两侧上颌第三前磨牙颊侧和腭侧根分叉区各植入一枚微型种植体,使橡皮链跨越牙齿(牙合)面施力,力量控制为100 g,分别于加力后0、1、3、7、14、30 d处死一只犬,取第三前磨牙及其牙周组织进行标本处理、组织切片、HE染色观察.结果:第三前磨牙根尖区、根分叉区与牙槽嵴顶部牙周组织改建最为活跃,主要表现为骨吸收;而唇腭侧与近中远中侧牙周组织改建不显著.结论:应用种植体支抗压低犬第三前磨牙时,牙齿仅发生垂直向的压低移动.若压低牙齿力值过大, 会导致根尖吸收,因此在临床应用中应注重力值大小的选择,并尽可能使用持续性的力量压低牙齿.     

牙周膜牵引成骨正畸牙快速移动中牙根吸收的研究

目的 :定量观察牙周膜牵引成骨牙齿快速移动中被移动牙受压侧牙根吸收程度 ,为其临床应用提供参考。方法 :6只犬 ,每只犬下颌左右两侧分别为实验侧和对照侧 ,对照侧用传统方法以第三前磨牙为支抗牙移第一前磨牙向远中 ,实验侧用自制牙周膜牵引装置。终止实验后取两侧第一前磨牙 ,扫描电镜观察其压力侧牙根 ,并拍摄照片 ,计算机图象分析系统测量牙根吸收程度。结果 :实验侧和对照侧都有牙根吸收 ,但牙根吸收的程度没有显著性差异。结论 :在本实验条件牙周膜牵引技术与传统的正畸技术在引起牙齿移动时的牙根吸收无显著性差异 ,说明其在大幅度提高牙齿移动速度的同时并不增加牙根吸收。     

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。     

犬牙槽骨牵张成骨快速移动牙齿的实验研究

目的:观察牙槽骨牵张成骨技术快速移动牙齿的实用性和有效性,为临床应用提供实验依据。方法:犬10只,随机分为5组,每组2只,拔除下颌两侧第二前磨牙,实验侧行牙槽骨牵张成骨术,安装自制牵张装置,5d后加力,每次0.25mm,每日2次;对照侧行传统正畸。持续加力2周后停止。分别于保持期第0,1,2,4,6周处死2只动物。标本行大体、x线片及组织学观察。结果:实验侧移动牙移动距离为(4.002±0.266)mm,对照侧为(1.154±0.155)mm,差异显著(P<0.001),未见明显并发症。结论:利用牙槽骨牵张成骨技术可以显著提高牙齿移动速度。     

国产微螺钉种植体支抗压低牙齿动物实验研究

目的研究国产微螺钉种植体支抗压低磨牙过程中种植体-骨界面结合状况及种植体稳固度。方法4条成年Beagle犬分别于双侧下颌前磨牙根尖下植入国产微螺钉种植体共8枚。植入后即刻以种植体为支抗对下颌前磨牙施以压低力，力值100g，时间3个月。加力结束后进行种植体及其周围组织的组织学检查。结果所有被加载的8枚种植体均保持良好稳固度，无移位。下颌前磨牙垂直高度平均减小3．12mm，同时出现了一定程度的颊侧倾斜，未见明显根尖及根分歧牙骨质吸收。加载种植体平均骨整合率为39．5％。结论微螺钉种植体支抗可以完成牙齿的压低移动并可保持良好稳固度。骨整合主要发生在种植体-皮质骨界面，松质骨中极少发生骨整合。     

A clinical and histological evaluation of titanium mini-implants as anchors for orthodontic intrusion in the beagle dog.

The aim of this study was to determine the anchorage potential of the titanium mini-implant for orthodontic intrusion of the mandibular posterior teeth. Six mini-implants were surgically placed around the mandibular third premolars on each side in 3 adult male beagle dogs. On the buccal site, three mini-implants were placed distal to the apex of the distal root of the third premolar, at the interradicular septa of the third premolar, and mesial to the apex of the mesial root of the third premolar, as linearly as possible. The same procedure was performed at the lingual site on both sides of the mandibular third premolars in each dog. Bilateral interradicular mini-implants on both the buccal and the lingual sites were used as the anchorage for the intrusion of the third premolars (loaded implants) and the other mini-implants were used as control (unloaded) implants. In 6 weeks, an intrusive force (150 g) was applied between the interradicular implants on the buccal and the lingual sites by closed coil springs run across the crowns of the third premolars. After 12 to 18 weeks of orthodontic intrusion, the animals were killed and their mandibles were dissected and prepared for histologic and fluorescent observation. The results indicated that the mandibular third premolars intruded 4.5 mm, on average, after 12 to 18 weeks of orthodontic force application, with mild root resorption at the furcation area as well as the root apex. All the mini-implants remained stable during orthodontic tooth movement without any mobility or displacement. The morphometrical findings indicated that the calcification of the peri-implant bone on the loaded implants was equal to or slightly greater than those of the controls. In addition, 6 of the 36 mini-implants were removed after tooth movement, and all of them were easily removed with a screwdriver. These findings suggest that mini-implants are effective tools for the anchorage of orthodontic intrusion in beagle dogs.     

不同牙槽骨高度的磨牙压低时牙周膜应力分析

目的：通过建立具有不同牙槽骨高度的上颌第一磨牙三维有限元模型,在压力载荷下,计算分析其牙周膜应力的大小和分布,为正畸治疗提供力学参考。方法：采用CT对上颌第一磨牙进行扫描,建立牙槽骨发生不均衡水平吸收的上颌第一磨牙的三维有限元数字模型,计算加载垂直向的压低力时,牙周膜应力的大小和分布。结果：当牙槽骨从正常高度降低3.5 mm时,加载产生的牙周膜应力增加平缓,高应力集中部位在根分叉处;而牙槽骨降低超过6.0 mm,根分叉部分暴露时,牙周膜应力明显增加,应力集中的部位转移至根尖及根1/3处。结论：当牙槽骨高度降低未超过6 mm时(牙槽骨吸收未超过根长的48%),应根据牙槽骨的丧失程度来减小矫治力值;当牙槽骨高度降低6 mm以上时(牙槽骨吸收超过根长48%),磨牙的根分叉完全暴露,则应显著减小矫治力值。     

Root resorption after orthodontic intrusion and extrusion: an intraindividual study

The aim of this investigation was to compare root resorption in the same individual after application of continuous intrusive and extrusive forces. In nine patients (mean age 15.3 years), the maxillary first premolars were randomly intruded or extruded with a continuous force of 100 cN for eight weeks. Eleven maxillary first premolars from six randomly selected orthodontic patients served as controls. Root resorption was determined using scanning electron microscopy. Quantitative assessment of the percentage of resorbed area of the total root surface was performed on composite micrographs. The severity of root resorption was also assessed by visual scoring of the roots. Root resorption mainly occurred at the apical part of the roots in both experimental groups. A significant difference in root resorption was found between the intruded and the control teeth (P = .006) but not between the extruded and the control teeth. However, the mesial and distal root surfaces showed resorption on 5.78 +/- 3.86% of the root surface of the intruded teeth and 1.28 +/- 1.24% of the root surface of the extruded teeth, and this difference was significant (P = .004). In addition, a large individual variation was found. From this study, it can be concluded that intrusion of teeth causes about four times more root resorption than extrusion. Because the amount of root resorption due to intrusion or extrusion in the same patient is correlated, every clinician should be aware that the extrusion of teeth might also cause root resorption in susceptible patients.     

Experimental tooth movement through mature and immature bone regenerates after distraction osteogenesis in dogs.

The purpose of this study was to verify the influence of tooth movement on tooth roots and periodontal tissues when teeth were moved into mature, well-organized, and mineralized regenerate bone created after distraction osteogenesis compared with immature, fibrous, and less-mineralized bone. Six 15-month-old male beagles underwent 10 mm of bilateral mandibular distraction osteogenesis. After 2-week (group 1) and 12-week (group 2) consolidation periods, third premolars were moved distally into the regenerate bone with 100 g of orthodontic force for 12 weeks. Simultaneously, second premolars were also moved distally as controls. After completion of tooth movement, the experimental animals were killed, and their tissues were harvested for histological evaluation. When premolars in groups 1 and 2 were compared, group 1 showed higher rates of tooth movement until the eighth week of experimental tooth movement (P <.05). The amount of tooth movement was significantly greater in group 1 than in group 2 or in the control teeth (P <.05). In group 1, we observed considerable root resorption extending into the dentin, and the thickness of the dentin became approximately half that of the controls at the compression side adjacent to the distraction gap. This root resorption extended from the cementoenamel junction to the root apex. In group 2, root resorption on the compression side reached the dentin, but the root resorption was less than in group 1. These results indicated that heavy force and early orthodontic tooth movement are not recommended when teeth are moved through regenerated bone created by distraction osteogenesis, to avoid tipping and severe root resorption.     

Effects of maxillary molar intrusion on the nasal floor and tooth root using the skeletal anchorage system in dogs

The skeletal anchorage system (SAS) was developed to provide intraoral absolute anchorage for the intrusion or distalization of molars. The purpose of this study was to verify the effects of remarkable molar intrusion on the tooth root and the maxillary sinus floor. Six adult female beagles with fully erupted dentition were used. Titanium miniplates were implanted bilaterally above the maxillary second premolar root apices using pentobarbital anesthesia. The second premolars were intruded for four or seven months after three months of healing after implantation. Standardized dental radiographs were taken periodically to evaluate the amount of tooth movement and root resorption. After the experimental animals were fixed by perfusion at the end of each experimental period, the second premolars were dissected along with the surrounding alveolar bone. Undecalcified (60 microm thick) and decalcified (five microm thick) sections were prepared. The average extent of intrusion was 1.8 mm after four months and 4.2 mm after seven months. The root apices of the intruded molars penetrated into the nasal cavity. Remodeled bone around the intruded molar toots was rich in woven bone on the buccal side, whereas that on the palatal side was rich in lamellar bone. Nasal floor membrane and a thin layer of newly formed bone, which lifted intranasally, covered the intruded molar root. Root resorption partly reached into the dentine without the formation of reparative cementum, and little or no serious pathological changes were seen in the pulp of the intruded molars. SAS effectively intruded maxillary molars, but some moderate root resorption was observed.     

牙周膜牵张成骨快速移动牙齿的组织学观察

目的 观察牙周膜牵张成骨快速移动牙齿的牙周组织学变化。方法 将6只杂种犬随机分为2w，4w，6w三组（每组二只）。拔除两侧第二前磨牙，并随机选择其中一侧为实验侧，另一侧为常规橡皮圈加力方法对照侧。动物基牙预备：拔牙凿骨减阻；粘结自制牵张装置；实验组以2次／天的频率、0．15fnm／次的速率加力，2w后固定保持。对照组以传统橡皮链对移动牙施加100g力值，加力2w后，固定保持。测量支抗牙、移动牙移动距离：分别于第2、4、6w各宰杀二只动物，观察实验侧与对照侧的组织学变化。结果 ①实验侧移动牙加力2w平均向远中移动3．78mm，对照侧移动牙平均向远中移动1．09mm（P〈0．01），实验侧支抗牙平均向近中移动0．42mm，对照侧支抗牙平均向近中移动0．40mm（P〉0．01）。②组织学观察得出：2w组，实验侧与对照侧相比，实验侧牙周膜显著增宽，牙周膜内成纤维细胞增殖，新生板层状牙槽骨明显增多，与牵张作用力方向一致；4w组，旧间隔骨已改建完成，牙周膜宽度基本恢复正常；6如组两种方法作用下移动牙牙周组织己无明显差异。结论 牙周膜牵张成骨可以快速移动牙齿；牙周组织不会出现不可复性损害。     

The effect of orthodontic extrusion on traumatically intruded teeth

The management of traumatically intruded permanent incisors is controversial. Some authors suggest a decreased incidence of ankylosis in cases treated with orthodontic extrusion. The purpose of this study was to examine two common management techniques for traumatic intrusion, orthodontic extrusion, and observation for re-eruption. The four first premolars of three shepherd dogs were traumatically intruded with a mallet while a holding device was used to prevent tooth fracture. Five to 7 days following the injury, orthodontic force was applied unilaterally while the contralateral tooth served as the untreated control. To facilitate serial periapical radiography, x-ray jigs were fabricated for each animal and tantalum implants were placed in the bone distal to the permanent canine and first and second premolars. Observations included radiographic measurement of tooth movement, clinical estimates of tooth mobility, and radiographic and histologic assessment of root resorption, ankylosis, and periapical pathosis. The amount of traumatic intrusion varied from less than 0.5 to 4.1 mm. Following 11 to 13 weeks of force activation, 10 of 12 traumatized teeth showed clinical, radiographic, and histologic evidence of ankylosis irrespective of orthodontic treatment. Whereas the ankylosed teeth did not move with orthodontic forces, the teeth used for force application were orthodontically intruded 1.7 to 6.5 mm. When the injury to the tooth was severe, orthodontic extrusion had little effect on repositioning of the injured tooth but resulted in undesirable movement of the anchorage teeth. When the injury was less severe, orthodontic forces facilitated repositioning of the affected tooth.     

固定矫治技术配合微种植体支抗压低磨牙的临床研究

目的探索口腔正畸临床应用微种植体支抗压低磨牙的方法与效果。方法用微种植体支抗和固定矫治技术对10例伴17颗上颌伸长磨牙的各类错畸形进行了矫治,共种植微螺钉34枚,种植于伸长磨牙的颊侧近远中牙槽间隔,种植后即刻用结扎丝结扎,2周后负载,并对种植体支抗压低磨牙所需的时间、采用的方法和效果进行计算和评价,对强支抗病例及磨牙牙周情况较差不宜作为支抗牙的病例,种植于伸长磨牙的近中的微螺钉还可用做后续支抗关闭拔牙间隙。结果17颗上颌伸长磨牙均获得了有效压低,平均压低2.8mm±1.3mm,压低时间平均3.2±0.7个月,压低后的磨牙颊舌向转矩正常,未出现舌尖伸长现象,10例错畸形病例也获得了满意的矫治效果。结论微种植体支抗可有效压低伸长磨牙,且由于配合了固定矫治技术,微螺钉只需种植在伸长磨牙的颊侧近远中牙槽骨,压低过程中磨牙的颊舌向转矩在固定矫治的过程中可得到有效控制,对强支抗等特殊要求病例,压低作用完成后的微螺钉还可作为支抗内收前牙及关闭拔牙间隙。     

牙槽骨缺损修复后牙齿移动的动物实验

目的探讨用组织工程方法修复大鼠下颌骨缺损对牙齿移动的影响。方法选用40只SD大鼠，获取大鼠骨髓基质细胞，分离培养并诱导为成骨样细胞。将成骨样细胞与陶瓷化骨复合，种植到大鼠下颌骨的一侧全层骨缺损区。缺损修复8周后，在手术组和正常对照组大鼠下颌安装正畸矫治器，加力近中移动第一磨牙。观察牙齿移动距离和牙根长度的变化，t检验比较组间差异。结果加力初期，手术组大鼠的牙齿移动距离大于对照组，差异有统计学意义（P〈0．05）。手术组牙根长度变化小于对照组，差异有统计学意义（P〈0．05）。结论应用陶瓷化骨复合体外诱导的大鼠自体成骨样细胞，可修复大鼠的下颌骨缺损，修复手术不会对牙齿移动产生不良影响。     

Using orthodontic intrusion of abraded incisors to facilitate restoration: the technique's effects on alveolar bone level and root length

BACKGROUND: The authors examined the effects of orthodontic intrusion of abraded incisors in adult patients to facilitate restoration, focusing specifically on changes in alveolar bone level and root length. METHODS: The authors analyzed records of 43 consecutive adult patients (mean age 45.9 years). They identified intrusion by means of cephalometric radiographs and bone level and root length by means of periapical radiographs. They calculated treatment differences from the pretreatment period to the posttreatment period. RESULTS: In general, bone level followed the tooth during intrusion, but a small amount of bone loss occurred (P< .0001). There were no significant associations with age, sex, treatment time, intrusion or pretreatment bone level. All intruded teeth exhibited significant root resorption during treatment (mean=1.48 millimeters). However, the change was similar to that seen in incisors that were not intruded. There were no associations with age, sex, treatment time or intrusion, but there was a positive relationship between pretreatment root length and root resorption. CONCLUSIONS AND CLINICAL IMPLICATIONS: Incisor intrusion in adults moves the dentogingival complex apically and is a valuable adjunct to restorative treatment. Potential iatrogenic consequences of alveolar bone loss and root resorption are minimal and comparable with the consequences of other orthodontic tooth movements.