下颌骨牵引成骨区即刻牙移动的实验研究

目的：研究下颌骨牵引成骨后在新骨区即刻牙移动时牙周组织的改建行为及牙移动规律。方法：选择4只牙列完整的Beagle犬,其中2只犬建立双侧下颌骨牵引成骨动物模型,牵引完成后,即刻以30g力远中移动下颌第三前磨牙进入牵引成骨区;另外2只犬拔除双侧下颌第四前磨牙后3个月,以30g力远中移动下颌第三前磨牙。实验中,每周加力1次拍摄X线片,并记录牙移动速率。牙移动8周后,观察实验牙及其牙周组织特点。测量数据采用SPSS12.0软件包进行t检验。结果：实验牙借助自制的持续加力装置移动进入牵引成骨区,实验牙未产生倾斜,牙无明显松动,牙根未见明显吸收。实验组牙移动速度显著快于对照组,P〈0.01。组组织学观察发现,牙槽骨和牙周膜未出现不可逆性损伤。结论：牵引成骨区的新生骨质中,牙可以快速而平稳地移动。     

正畸治疗中快速远中移动尖牙的CBCT研究

目的：研究正畸治疗过程中快速移动尖牙术后牙根的吸收和改建。方法选取安氏Ⅱ类错成年患者15例,减数双侧上颌第一前磨牙,牙周膜牵引成骨术快速远中移动尖牙26颗,术前及术后3个月分别拍摄CBCT,测量牙根长度及牙槽骨的改建情况。结果26颗尖牙在2至3周内快速远中移动到位,尖牙快速远中移动术后3个月无明显的牙根吸收,尖牙近中骨组织密度正常。结论快速移动尖牙安全有效,可缩短正畸疗程。     

应用正畸移动装置在牵引成骨新成骨中移动牙的动物模型的建立

目的探讨应用自制正畸移动装置在牵引成骨新成骨中移动牙的方法的可行性,建立动物模型,为临床应用提供客观理论依据。方法将六只成年（12～15月龄）雄性小尾寒羊（绵羊）的下颌两侧随机分组,随机选择一侧为实验组,另一侧为对照组。实验组按照骨成熟期分为一周组、两周组、三周组、四周组（非成熟骨组）和半年组、一年组（成熟骨组）。对照组分为常规对照和空白对照。非成熟组对侧为常规对照,成熟骨组对侧为空白对照。实验组在下颌第一双尖牙的近中牙槽嵴位置行手术骨皮质切开,放置牵引成骨器,术后5天开始牵引成骨,每12小时牵引加力一次,1．2mm／d,牵引6天,在第一双尖牙近中形成7．2mm新生骨段;分别在一周、两周、三周、四周和半年、一年后,在第一双尖牙近中约2cm位置牙槽嵴顶植入种植钉作为支抗,使用正畸轻力移动牙齿的方法应用镍钛拉簧牵引第一双尖牙向近中移动,力值约100g（0．98N）,3周后第一双尖牙移入牵引成骨骨段。常规对照组,使用同样正畸方法牵引第一双尖牙向近中移动3周。结果实验组牙齿顺利移动进入牵引成骨骨段,松动度Ⅰ度,局部牙龈红肿、轻度炎症,X线检查示无X尖周病变、无明显牙根吸收。结论使用正畸力在牵引成骨新成骨中移动牙齿的方法切实可行,本研究所建立的动物模型可以应用于后续的研究中。     

牙周膜牵引成骨快速牙移动的临床研究

目的研究牙周膜牵引成骨术在正畸临床治疗中的效果及问题。方法选择因正畸治疗减数上颌第一前磨牙的13例病例,共22颗尖牙,在第一前磨牙减数并行牙槽窝外科处理后,第二前磨牙及第一磨牙作为支抗牙,采用自制牵引器远中移动尖牙,牙髓电活力测试及影像学评估牙齿状况。结果22颗尖牙在平均16．7d内远中平均移动4．6mm,未出现支抗牙前移、牙根吸收及牙髓活力变化。结论牙周膜牵引成骨可以快速有效移动尖牙,未出现明显的支抗丧失及牙齿损伤。     

Experimental tooth movement through regenerate alveolar bone: A pilot study.

The purpose of this pilot study was to experimentally evaluate tooth movement through regenerate bone at an early time point during the consolidation phase after bilateral mandibular osteodistraction. Two beagle dogs underwent 10 mm of bilateral mandibular lengthening via intraoral distraction osteogenesis between the fourth premolars and first molars. After 1 week of consolidation, retraction of the fourth premolars was initiated. Immediately after completing premolar retraction, the dogs were sacrificed and the mandibles were analyzed radiographically, histologically, and by dental cast measurements. Initially, all 4 fourth premolars moved distally, with 2 of the 4 touching the first molars at the time of sacrifice. Based on the current data, it is possible to move teeth through regenerate bone, and it appears that tooth movement can begin within weeks of starting the consolidation period.     

牵张成骨区牙移动动物模型的建立

目的:建立双侧下颌骨牵张成骨区快速正畸牙移动的实验动物模型,为其后的系列研究建立可靠的实验平台。方法:选择8只牙列完整的Beagle犬,其中4只犬建立双侧下颌骨牵张成骨动物模型,牵张完成后即刻以150g力远中移动下颌第三前磨牙进入牵张成骨区;另外4只犬拔除双侧下颌第四前磨牙后3个月,以150g力远中移动下颌第三前磨牙。实验中,每周加力1次,拍摄X线片并记录牙移动速率。牙移动8周后,观察实验牙及其牙周组织特点。结果:接受牵张成骨手术的4只犬,双侧下颌骨均被成功延长1cm,前牙出现反合,无实验犬死亡。实验牙借助自制的持续加力装置移动进入牵张成骨区。实验组牙移动显著快于对照组,X线观察实验组牙移动进入牵张成骨区,牙根未见明显吸收。组织学观察压力侧牙槽骨和牙周膜未出现不可逆性损伤。结论:以Beagle犬为实验对象,用成品牵张成骨器借助种植支抗钉和自制的牙移动装置远中移动下颌第三前磨牙,可建立可靠的动物模型。     

Rapid orthodontic tooth movement into newly distracted bone after mandibular distraction osteogenesis in a canine model.

Orthodontic tooth movement through recently distracted fibrous bone tissue has not been investigated previously. We hypothesized that a tooth can be moved into the fibrous new bone created by the distraction process at a rapid rate. Four mature beagle dogs were used in this study. An edentulous space was created in 2 weeks by using a bone-borne intraoral distraction device on each side of the mandibular body between the third and fourth premolars. Calibrated elastic threads with 50 g of orthodontic force were applied to move the fourth premolar into the edentulous space for 5 weeks. On one side, the tooth was moved simultaneously with distraction; and on the opposite side, it was initiated immediately after the cessation of distraction. The fourth premolars were moved 1.2 mm per week. The results indicated that the best time to initiate tooth movement was immediately after the end of distraction. With this approach, most of the periodontal support was preserved after orthodontic tooth movement. In contrast, moderate to severe alveolar bone loss was noted in the fourth premolars moved simultaneously with distraction. This is one of the first experimental studies to demonstrate successful rapid orthodontic tooth movement into an edentulous space newly created by distraction osteogenesis. Clinical implications of these results may be applied to relieve severe dental crowding and to correct sagittal or transverse dental arch discrepancies.     

Dentoalveolar distraction osteogenesis for rapid orthodontic canine retraction.

PURPOSE: We present a technique to reduce the overall orthodontic treatment time by means of dentoalveolar distraction osteogenesis. PATIENTS AND METHODS: Eleven patients who were planned to undergo orthodontic treatment with bilateral first premolar extractions and subsequent bilateral canine tooth distalization underwent osteotomy around the canine tooth. The first premolar was extracted, and the buccal bone was carefully removed. After wound closure, a special orthopedic device was mounted and cemented to the first molar and canine teeth. Distraction was started the same day at the rate of 0.4 mm twice a day and continued until adequate movement of the canine teeth was achieved. The device was then removed, and orthodontic therapy was continued with fixed appliances. RESULTS: The distraction rate and the device were well tolerated by all of patients. No anchorage loss in the second premolar and first molar teeth, root resorption, dental ankylosis, discoloration, or loss of vitality was detected. CONCLUSION: The concept of distraction osteogenesis for rapid orthodontic tooth movement is promising and feasible for clinical practice.     

牵张成骨区快速牙移动压力侧牙周组织的改建

目的:观察牵张成骨区早期快速移动牙压力侧牙周组织的改建,为牵张成骨区早期快速牙移动的安全性和可行性提供实验依据.方法:选择10只雄性Beagle犬,采用自身对照设计,随机选择犬的一侧下颌骨行牵张成骨术作为实验组,利用正畸种植钉作为支抗,牵张完成后,即刻以30g力远中移动第3前磨牙(P3)进入牵张成骨区.对侧拔除下颌第四前磨牙(P4)后,以30g力同期远中移动P3作为对照组.每周用游标卡尺测量第三前磨牙远中移动的距离,每个距离测量3次,取其平均值并记录,采用SPSS18.0软件包对相关数据进行配对t检验.分别于牙移动1、2、4周后,取材行HE染色及抗酒石酸酸性磷酸酶(TRAP)染色,观察移动牙的压力侧牙周组织的变化.结果:牵张成骨区牙平均移动速度达到每周(1.055±0.054)mm,明显快于对照组,差异具有统计学意义(P＜0.05),且无明显迟滞阶段.实验组移动牙的牙周组织压力侧未观察到透明样变性,牙根表面吸收陷窝少见,而TRAP染色阳性细胞的数量和面积均大于对照侧,且表达更强.结论:牵张成骨新骨区牙移动速度明显加快,无明显迟滞阶段;可能与移动牙牙周组织的压力侧未观察到透明样变性,破骨细胞出现早,范围广,破骨活动更为活跃有关.     

A study of the anterior portion of the palate as it relates to orthodontic therapy.

1. The anterior portion of the palate does not appear to move lingually as orthodontic forces move incisor teeth lingually. Although the alveolar bone directly supporting the teeth can be moved distally (and elongated), it does not appear possible to move the apex of the root more distally than the pretreatment position of the palatal plate. Thus, there appears to be an anatomic limitation to the distal movement of maxillary incisor teeth. 2. When incisor teeth are moved distally within the boundaries of the present alveolar process, the supporting bone does not remodel to the roots' new position; when a root which was initially positioned nearer the labial alveolar plate is moved distally against the palatal plate, there was observed no adaptation in the bone to have the root once again located near the labial alveolar plate, the root remained stable against the palatal plate. 3. When great distal movement of incisor teeth results in an alteration in position of the supporting alveolar bone, remodeling of the bone maintains a relatively constant labiolingual width of this alveolar bone. The new position of the tooth and supporting bone appears to be stable. 4. The scanty metallic implant evidence would seem to support histologic observations that alveolar processes are remodeled by apposition of bone on the cortical plate toward which the tooth is moving and resorption of the cortical plate away from which the tooth is moving. 5. There does not appear to be a statistically significant correlation between posterior facial measurements (SNMP) and the labiolingual width of the anterior palate.     

Comparative evaluation of dento-alveolar distraction and periodontal distraction assisted rapid retraction of the maxillary canine: a pilot study

Distraction osteogenesis is a biological process of new bone formation between the surfaces of the bone segments that are gradually separated by incremental traction. A recent innovative use of distraction osteogenesis in orthodontic tooth movement is to move individual tooth segments rapidly thus reducing orthodontic treatment time. Six patients, comprising two groups, were compared using two different surgical techniques: dento-alveolar distraction and periodontal distraction to bring about rapid canine retraction using an indigenously designed intra-oral distractor. The aim was to assess and evaluate the best approach to reduce the overall orthodontic treatment time by means of distraction osteogenesis. The patients were assessed at regular intervals with intra-oral periapical radiographs and lateral cephalograms for gauging the time required for retraction, canine tipping, anchorage loss and external root resorption. Dento-alveolar distraction was superior to periodontal distraction in all areas of assessment.     

Constant versus dissipating forces in orthodontics: the effect on initial tooth movement and root resorption

The aim of this clinical and confocal laser scanning microscopic study was to compare the effects of two frequently used archwires on tooth movement and root resorption. A total of 84 premolars in 27 individuals (10 boys, 17 girls, with a mean age of 12.5 years) was moved buccally with an experimental fixed orthodontic appliance. In a split mouth experimental design the premolar on one side was activated with a stainless steel wire with a buccal offset of 1 mm, which was reactivated every four weeks and the contralateral premolar was moved with a superelastic wire with a force plateau of 0.8-1 N. This wire had an initial activation of 4.5 mm and was not reactivated during the 12-week experimental period. At the end of the experimental period the teeth were extracted. Six premolars were used as control teeth and were extracted before the experiment started. Tooth displacement was studied three-dimensionally on dental casts with a co-ordinate measuring machine. The depth, perimeter, area, and volume of the resorption lacunae was measured using three-dimensional digital images made with a confocal laser scanning microscope (CLSM). On these images the resorbed portions of the root surface were 'reconstructed' mathematically. The results show that the teeth activated with the superelastic wire moved significantly more than the teeth with the steel wire during the experimental period. The depth of the resorption lacunae did not differ significantly between the groups; however, perimeter, area, and volume of the resorption lacunae on the teeth of the 'superelastic group' were 140 per cent greater than on the teeth of the 'steel group'. It may be concluded that a greater amount of tooth movement occurred with superelastic wires, offering a force level of 0.8-1 N compared with stainless steel wires, with initially higher but rapidly declining forces in an experimental set up for a period of 12 weeks. The amount of root resorption was significantly larger in the superelastic group.     

骨转换率对大鼠正畸牙齿移动量及牙根吸收的影响

目的:研究在不同骨转换率的条件下,大鼠牙齿移动过程中牙齿移动量及对牙根吸收的影响。方法:健康成年雄性威斯塔大鼠30只,体重180～220g。随机分成3组:高骨转换率组,低骨转换率组,正常对照组。前2组通过20d甲状腺片和丙硫氧嘧啶灌胃得到高骨转换率和低骨转换率组动物模型。左侧上颌第一磨牙加力21d。在处死动物前15d及2d添加骨标志物。拍X线片测量牙齿移动距离及牙根长度。结果:高骨转换率组的大鼠正畸牙齿移动的距离长,牙根最长。结论:骨转换率对正畸牙齿移动量及牙根吸收有影响。骨转换率高则大鼠牙齿移动量大,牙根吸收少,反之大鼠牙齿移动量小,牙根吸收多。     

Pulp-dentine complex changes and root resorption during intrusive orthodontic tooth movement in patients prescribed nabumetone

Pulpitis, external root resorption, and pain may be experienced during orthodontic movement. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) has been suggested to control these changes. The purpose of this study was to observe pulp-dentinal reactions, root resorption, tooth pain, and tooth movement after the application of a 4-ounce intrusive orthodontic force to human maxillary first premolars in patients given the NSAID nabumetone. Thirty-four maxillary first premolars were evaluated. A placebo was prescribed to 17 patients after an intrusive force was activated and reactivated for an 8-week period on the right side. The same procedure was repeated on the left side after patients were given nabumetone. Pulp-dentinal reactions and external root resorption were evaluated by histology. Pain and movement were also evaluated. Nabumetone was found to be useful in reducing pulpitis, external root resorption, and pain caused by intrusive orthodontic movement, without altering tooth movement in response to the application of orthodontic force.     

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.     

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.     

Application of calcium phosphate ceramics to periodontal therapy. 8. Effects of orthodontic force on repaired bone with hydroxyapatite

It has been unclear whether M.T.M. is acceptable for patients treated with bone grafts using hydroxyapatite (HAP), which is not biodegradable. Therefore we studied histological changes in bone among HAP during orthodontic tooth movement. HAP was implanted into artificial bone defects adjacent to second premolars in beagle dogs, and as a control no material was implanted Three months after implantation, the second premolars were moved with orthodontic force. Then they were observed histopathologically. The results obtained were as follows. The amount of movement of the teeth in implanted sites was less than in the controls. In the pressure zone, resorption of bone by osteoclasts was observed in both the implanted and the control sites, in addition, root resorption occurred adjacent to HAP. Furthermore multinucleated giant cells were closely attached to HAP and were surrounded by bone and connective tissue. In retention period there was ankylosis between the roots and bone around HAP. In the tension zone, additional bone from HAP was observed. Bone defects were filled with bone in the implanted sites, but with connective tissue in the controls. These results suggest that bone among HAP was resolved by osteoclasts. Clinically, HAP implantation for the pressure zone should be avoided because of the occurrence of root resorption and ankylosis. But for the tension zone it seems to be effective because HAP implantation produces more repaired bone.     

Nonsurgical management of ectopic teeth

Four cases have been presented involving malpositioned premolars and molars that were brought into the arch. From the cases presented, it appears that aggressive surgical intervention to redirect ectopic premolars creates significant secondary problems. Interference with the bone surrounding the ectopic tooth may compromise the adjacent teeth and bone level. Pressure against the root of the impacted tooth may cause resorption. If the buccal or labial plate is removed, orthodontic movement will be impeded. Specific biochemical changes in bone are induced by the application of orthodontic forces. In these cases, creating space with coiled spring appliances resulted in remarkable reorientation and proper eruption of ectopic, impacted teeth. When surgical intervention is required in cases involving ectopic teeth, close collaboration between orthodontist and oral and maxillofacial surgeon is imperative to achieve successful results without negative sequelae.     

The effect of physiological root resorption on repair potential of primary tooth pulp

The aim of this study was to determine, the effects of root resorption on repair potential of healthy deciduous tooth pulps. Fourteen canine teeth which needed to be extracted for orthodontic purposes and in which resorption had just begun (1st group, resorption did not exceed 1/3 of root length) or was in advanced resorption stage (2nd group, resorption was between 1/3 and 2/3 of root length) were used for this study. Direct pulp capping treatment was implemented in vivo, to 7 teeth in each group. Reparative dentin formation was determined three months later following extraction. The teeth were examined histopathologically under light microscope. As a result, in the teeth with different resorption levels, dentin bridge formation in the capping area was observed. Although maturation of the thin dentin bridges was completed in all teeth, maturation of the thick dentin bridges was still continuing at the 90th day.     

Rapid orthodontic treatment after the ridge-splitting technique--a combined surgical-orthodontic approach for implant site development: case report

This article presents a clinical case of bilateral partial edentulism in the posterior mandible with severe horizontal and moderate vertical bone atrophy. A new technique using rapid orthodontics after ridge splitting is presented. The split-crest technique was carried out using piezosurgical instruments in the first molar and second premolar areas to widen the bone crest and open a channel for tooth movement. Immediately after, orthodontic appliances were used to move the first premolars distally and the second molars mesially into the surgical site. The rationale was to facilitate and accelerate orthodontic movement of the teeth, which is otherwise difficult in a cortical knife-edged ridge. The bone defect was filled with the alveolar bone of the adjacent teeth that were moved into the surgically opened path. Adequate bone volume for implant placement was generated in the first premolar area. Implants were then inserted, and the patient was rehabilitated.