半侧颜面短小症牵张成骨治疗进展

半侧颜面短小症是仅次于唇腭裂的最常见的先天性颌面部畸形,临床表现多样,累及上下颌骨、颧骨、颞骨等多个颅颌面骨骼结构,同时伴有颜面软组织发育不全,常合并附耳、耳郭畸形等。牵张成骨技术治疗半侧颜面短小症,延长下颌骨,改善面部不对称畸形,疗效良好。该文就半侧颜面短小症牵张成骨治疗的进展进行综述。     

牵张成骨术矫正单侧真性关节强直偏颌畸形1例

对1例因关节强直导致的偏颌畸形患者行下颌骨体牵张成骨器植入术,术后1周开始牵张右侧下颌骨,牵张20 d后右侧下颌升支及下颌体高度明显增加,牵张器维持4个月,右侧上颌骨自动向下生长,上下颌咬合关系恢复正常,取出下颌牵张成骨器,在牵张成骨新骨上植入MEDPOR假体并行颏成形术。手术完成后患者颜面不对称及畸形咬合关系均得到明显改善。     

牵张方向对下颌骨体部牵张成骨应力分布与位移的影响

目的:研究牵张方向对下颌骨体部牵张成骨的影响。方法:建立下颌骨牵张成骨三维有限元模型,在下颌骨体部模拟牵张成骨,测量不同加载条件下,下颌骨的VonMises应力、颏顶点和右侧下颌角点的位移。结果:应力、位移量与加载力值成线性关系。应力集中在加载部位,双侧加载、与牙合平面平行方向加载时,VonMises应力更大,颏顶点、下颌角点表现为X、Z轴向的正位移和Y轴向的负位移;与下颌骨下缘平行方向的加载应力小,颏顶点、下颌角点表现为X、Y轴向的正位移和Z轴向的负位移。结论:单侧加载时下颌骨向对侧偏斜多,双侧加载时矢状向位移趋势大。与上颌牙合平面平行的加载较与下颌骨体下缘平行的加载应力大,但不会造成前牙开牙合。     

下颌角部牵张成骨的有限元分析

目的应用力学相似性较高的下颌骨三维有限元模型,分析角部牵张成骨对下颌内部应力分布及位移趋势的影响。方法在有限元模型的下颌角部模拟骨皮质切开并加载。结果获得角部单、双侧牵张成骨条件下,下颌骨内部应力分布和各部分位移的趋势。发现下颌骨角部牵张成骨应力集中在牵张部位。(牙合)平面有顺时针旋转的趋势,单侧加载较双侧加载下颌整体向对侧的位移趋势大。     

内置式牵引成骨技术治疗颌骨畸形

目的 :探讨内置式牵引成骨技术在不同类型的牙颌面畸形治疗中的应用。方法 :应用 2种类型的内置式牵引装置 ,为严重的小颌畸形、上颌后缩畸形、半侧颜面萎缩畸形和下颌骨缺损畸形患者行下颌骨体水平方向延长、上颌骨水平前徙、下颌升支与上颌骨同期垂直向延长以及下颌骨体部双端式牵引延长 ,共 5例。结果 :5例牵引成骨手术 ,部分病例辅助正颌外科手术 ,均达到术前设计要求 ,临床效果满意。 2例因牵引方向导致的错牙合问题 ,在牵引结束时及时得以纠正。无伤口裂开、感染、骨坏死、骨不连等并发症。结论 :应用内置式牵引成骨技术可重建面部轮廓 ,恢复理想的咬合关系和口颌功能 ,创伤小 ,安全可靠     

口腔颌面外科应用牵张成骨技术的实验研究进展

牵张成骨是指在骨缝处或在截开的骨段用牵张装置按一定的速度和频率牵开，在因此产生的骨间隙中形成新骨，从而达到使骨延长或增宽的目的。自７０年代以来，开始下颌骨牵张成骨研究，增加下颌骨的长度和改变下颌弓的宽度，以修复下颌骨缺损和矫正下颌骨横向畸形如牙弓狭窄，牙列拥挤等，而且人们进行了上颌骨牵张成骨研究，使前份上颌骨延伸及利用Ｌｅ Ｆｏｒｔ Ｉ截骨使骨段移动。牵张装置从口外型发展在为小巧的口内型。对牵张成     

弧形牵张成骨重建人体下颌骨颏部节段性缺损的三维有限元研究

目的:建立下颌骨颏部节段性缺损弧形牵张成骨的三维有限元模型,研究弧形牵张成骨重建下颌骨颏部节断性缺损过程中,不断变化方向的牵张力对新骨组织形成的影响。方法:建立颏部节段性缺损的三维有限元模型,并把简化后的弧形牵张器有限元模型置入截断后的下颌骨,模拟弧形牵张成骨,并测量在弧形牵张成骨过程中下颌骨整体位移及其von Mises应力分布。结果:在未考虑唇颊侧软组织作用的前提下,弧形牵张成骨形成的新骨向舌侧生长,重建的下颌骨弧度较原下颌骨弧度变小。von Mises应力主要集中于牵张器在下颌骨的固位处。结论:在弧形牵张成骨重建下颌骨缺损过程中,牵张力本身就促使新骨组织向舌侧生长,从而使重建的下颌骨弧度较正常时小。此项研究为临床上如何克服弧形牵张成骨所形成的下颌骨弧度较小的不足,提供了一定的理论依据。     

犬下颌骨单侧不全截骨牵张时牵张侧位移状况有限元分析

目的 运用犬下颌单侧不全截骨牵张成骨有限元模型,计算下颌骨在牵张过程中牵张侧各部分位移状况。方法 有限元模型模拟犬下颌单侧不全截骨牵张,观察当滑动骨块未被牵开和被牵开时牵张侧关节、下颌角、喙突及牙齿等6个标志点的位移状况。结果 下颌滑动骨块未被牵开时牵张侧第五臼齿、髁状突前斜面前缘中点所受最大主应力为压应力,髁状突后斜面后缘中点为拉应力,各标志点在空间X、Y、Z三轴位移不明显;当下颌骨滑动骨块被牵开1 mm时,上述各点位移明显增加。结论 从牵张侧观察,牵张侧下颌骨在矢状平面上和冠状平面上都有以髁突顶点(横嵴中点)为中心的逆时针旋转趋势。     

钛镍记忆合金牵张器复合脱细胞真皮基质增高犬牙槽嵴的组织学研究

目的通过对牵张成骨增高牙槽嵴新生骨的组织学观察,研究钛镍记忆合金牵张器复合脱细胞真皮基质对成骨质量的影响。方法健康成年雄性杂种犬12只,建立牙槽嵴萎缩模型后1个月,一侧下颌后牙区行牵张手术并放入2个“S”形牵张器及异种脱细胞真皮基质（ADM）,另一侧为对照侧,仅行牵张术,不放置ADM。术后1个月、3个月各处死6只实验犬。将牵张区骨组织进行脱钙骨组织学观察,参照Parfit方法进行定量组织学测量。动物处死后取双侧下颌第3前磨牙区骨块,直接做骨切片,荧光显微镜下观察。结果1个月时,实验侧的平均骨小梁体积分数、平均骨小梁厚度、平均骨小梁数目均高于对照侧,平均骨小梁分隔距离低于对照侧;3个月时,实验侧平均骨小梁体积分数、平均骨小梁数目高于对照侧,平均骨小梁分隔距离低于对照侧。结论ADM阻力膜能改善牵张过程中力学的平衡,阻止周围软组织长入,改善成骨环境,提高成骨质量。     

口内入路的颌骨牵引成骨技术

目的 探讨口内入路的颌骨牵引成骨技术在牙颌面畸形矫治中的应用。方法 使用６种不同类型的口内牵引器分别水平向延长上颌骨和下颌骨体,水平垂直双向延长下颌骨升支以及垂直向延长牙槽嵴,以矫正重度上颌后缩畸形、小下颌畸形、半侧颜面发育不全畸形以及颌骨缺损畸形等,共１２例。结果 １２例不同类型的颌骨牵引成骨除１例牵引器故障,中途更换,另１例发生下颌下缘骨折并发症外,无感染、成骨不良、骨不愈合开Ｈｅ等并发症,１     

Combined skeletal and soft tissue reconstruction for severe Parry-Romberg syndrome

Parry-Romberg syndrome is an acquired facial deformity that manifests as progressive hemifacial atrophy that has unknown cause. Many surgical techniques to address it have been reported, such as fat transplantation and use of free flaps. Undoubtedly, the results of such techniques can be satisfactory for mild hemifacial atrophy after soft tissue restoration. But in severe cases, except for large-scale soft tissue atrophy, the osseous framework is involved, rendering their management difficult, and the results are often inadequate. On the basis of the severity of facial soft tissue atrophy and the extent of involvement of the osseous framework, we classified the deformities into 3 groups: (1) Mild: the facial atrophic area is confined to a small region and is located in the lateral face, the nasal ala and upper lip are normal, and there is no deviation of the oral commissure, and the occlusal plane is horizontal. (2) Moderate: there are large areas of soft tissue atrophy, and the nasal ala and upper lip are also affected; the oral commissure is deviated; the bony framework is nearly normal; and the occlusal plane is nearly horizontal or slightly deviated. (3) Severe: moderate form of soft tissue atrophy and serious bone framework atrophy, involving the zygoma, maxilla, and mandible; the chin and occlusal plane have deviated extensively to the affected side.In this article, we report our experience in successfully treating 23 patients with severe Parry-Romberg syndrome, according to our classification; mild and moderate cases were not included in this series. Microsurgical flap transplantation, lipoinjection, liposuction revision, dermis grafting, and cross-lip flap were used to correct soft tissue deformities, and bone augmentation using the MEDPOR implant, orthognathic surgery, bone grafting, and mandibular distraction were performed to reconstruct the bone framework.     

Combined simultaneous distraction osteogenesis of the maxilla and mandible using a single distraction device in hemifacial microsomia

Facial asymmetry in hemifacial microsomia can be corrected by an effective procedure of gradual distraction of the mandible. In younger children with deciduous dentition, changes in dental occlusion secondary from mandibular distraction can be easily corrected with orthodontic treatment. In older patients, mandibular elongation through distraction osteogenesis can produce good aesthetics but can create a severe alteration in occlusion requiring complex orthodontic treatment during an extended period. A Le Fort I osteotomy was performed simultaneously with mandibular corticotomy to avoid this problem. We present an 11-year-old patient with grade II hemifacial microsomia with facial asymmetry that was corrected with a combined simultaneous distraction of the maxilla and mandible using a single mandibular distraction device and an interdental splint. Excellent facial symmetry was achieved while maintaining preexisting dental occlusion.     

Changes in width of lower face after unilateral mandibular distraction osteogenesis

Distraction osteogenesis (DO) has been popular to improve hypoplastic mandible in patients with hemifacial microsomia in craniofacial surgery. However, changes in width of the lower face after DO still lack in literatures. The aim of this pilot study was to evaluate cephalometric changes in width of the lower face at different time points after DO and to give an insight into the influence on facial contour. A total of 10 patients (8 males and 2 females) with hemifacial microsomia received DO of the mandibular body measured by posteroanterior cephalograms. Five landmarks (crista galli, latero-orbitale, gonion of the unaffected side, incisor point superior of the unaffected maxilla, incisor point inferior of the unaffected side of the mandible) were chosen for cephalometric analysis. Six distances from the soft tissue contour perpendicularly to the vertical reference line (through crista galli) were calculated through the incisor point superior of the unaffected maxilla, gonion of the unaffected side, incisor point inferior of the unaffected side of the mandible. Measurements were taken preoperatively and postoperatively on the day distraction started (time 1), at the end of distraction (time 2), and at the end of the consolidation period (time 3). Calculations for statistical significance were done for all patients. Mean differences between 3 periods were measured by repeated-measures analysis with significance determined at the 0.05 level of confidence. The results suggested that the values of 6 distances at times 2 and 3 had no significant differences when compared with the values at time 1 (P>0.05). In conclusion, DO of the unilateral mandibular body in patients with hemifacial microsomia should not be beneficial to improve the width of the lower face at a short-term follow-up.     

Two-year follow-up of distraction osteogenesis: its effect on mandibular ramus height in hemifacial microsomia.

Distraction osteogenesis has been used to lengthen the mandible in patients with hemifacial microsomia. Questions regarding soft tissue and skeletal growth after distraction osteogenesis have not been clearly elucidated in the literature. In this case report, a 2-year follow-up of distraction osteogenesis in a 7 year old boy is documented with lateral and posterior/anterior cephalometric analysis. The analysis was performed preoperatively and at specific postsurgical periods to evaluate the facial soft tissue and skeletal growth patterns. Objective analysis of this growing patient after distraction osteogenesis clearly demonstrates that the anteroposterior elongation of the mandible is relatively stable, whereas the vertical lengthening and soft tissue effects are minimal. Critical evaluation of other patients who have undergone distraction osteogenesis is needed to determine if this was an isolated incident or the expected result in similar patients.     

New approach for the surgico-orthodontic treatment of hemifacial microsomia

One of the important clinical findings in hemifacial microsomia (HFM) is facial asymmetry (FA) with unilateral underdevelopment and malformation of the mandible and/or maxilla. Unilateral distraction osteogenesis (UDOG) of the mandible has been used for correction of FA in HFM patients. However, return to the original FA status often occurs because of contraction of the distracted bony segment of the mandible and insufficient compensatory downward growth and skeletal midline correction of the maxilla on the affected side. Although bimaxillary UDOG procedure in the maxilla with Le Fort I osteotomy and the mandible with ramus osteotomy was suggested as an alternative treatment modality, it has some disadvantages including elongation of the face, inaccuracy of vector control, and less predictable results. Occlusal plane canting, skeletal midline deviation of the maxilla, and unilateral mandibular hypoplasia might be simultaneously corrected by fixation of the maxilla into a proper position after Le Fort I osteotomy and UDOG of the mandible. Three-dimensional virtual simulation using three-dimensional computed tomography data could help to accurately predict surgical outcomes. In addition, transarch elastic traction from the orthodontic mini-implants on the unaffected side of the mandible to the maxillary posterior teeth on the affected side can produce a plastic molding of the regenerated bone in the distraction area of the mandible and induce compensatory dentoalveolar downward development of the maxillary posterior teeth. Therefore, the purpose of this article was to introduce a new approach for the surgico-orthodontic treatment consisting of simultaneous maxillary fixation and unilateral mandibular distraction with transarch elastic traction in HFM patients.     

Longitudinal results of mandibular distraction osteogenesis in hemifacial microsomia

The aim of this study was to evaluate mandibular distraction therapy by three-dimensional (3-D) computed tomography (CT) imaging so as to be able to improve the treatment results. The study group consisted of eight children (3 male and 5 female) with hemifacial microsomia. For each child, CT scans of the head were available (Pro Speed S Fast Spiral scanner; General Electric). Longitudinal measurements of the mandible, bony and soft tissue 3-D reconstructions, and masticatory muscles were demonstrated. Three-dimensional CT scans provide important data concerning the results of mandibular distraction therapy and should be used in treatment evaluation. In some patients and for some muscles only, a small increase in the volume of the affected side of the masticatory muscles in comparison to the normal side was found 3 years after mandibular distraction. In around 50% of the cases, there seems to be a relapse occurring 1 year after distraction osteogenesis, and this relapse has a progressive character when seen 3 years after distraction osteogenesis in comparison to 15 weeks after distraction osteogenesis.     

Condyle as the point of rotation for 3-D planning of distraction osteogenesis for hemifacial microsomia.

AIM: The purpose of this study is to present an exact simulation method for mandibular rotational movement in distraction osteogenesis for hemifacial microsomia. METHODS: Three-dimensional (3-D) surgery simulation software programmes (V-Works and V-Surgery; Cybermed, Seoul, Korea) were used, based on 3-D CT data in addition to the conventional data, which included facial photography, panoramic radiograph, cephalogram, and dental models. After measuring the mandibular deficiency (horizontal and vertical) from a 3-D model reconstructed using the software, the angulation of the distraction device to the mandibular border (posterior or inferior) was determined. The rotation axis in the V-Works simulation was defined as the line perpendicular to the plane made by condylion and the distraction vector location on the mandible. The mandible moves along the plane around this rotational axis during distraction. After the 3-D simulation with the software programme, mock surgery on a rapid prototyping model was performed. This planning method was applied to models of two hemifacial microsomia patients. RESULTS: With this protocol, it was possible to simulate the rotational movement of the mandible on the axis passing through the condylar head of the unaffected side. CONCLUSION: The sequential planning procedure presented in this paper is considered to be helpful in performing effective preoperative simulation of distraction osteogenesis for hemifacial microsomia.     

Incomplete mobilization of the maxilla resulting in failed maxillary distraction: a case report

Maxillary distraction osteogenesis has become an accepted alternative method in the treatment of patients with severe maxillary hypoplasia in craniofacial syndromes and cleft-related deformities. Insufficient distraction, undesirable soft tissue changes, and occurrence of defective distraction vectors are among the potential complications of intraoral maxillary distraction osteogenesis. A 2-stage procedure combining maxillary advancement by distraction technique with genioplasty and mandibular setback surgery was planned to correct jaw deformities in a 22-year-old patient with severe maxillary retrusion, mandibular prognathism, and excessive lower facial height. In the first stage, osteotomies were performed and maxilla was lightly mobilized after down-fracture. Distractors were placed to the maxilla intraorally. During activation period, the maxilla rotated in a clockwise direction, producing a discrepancy between the planned and the actual vectors. Complete distraction was unsatisfactory and the complication was due to surgical technique. This case report presents the failure of maxillary distraction due to incomplete mobilization of the maxilla. Treatment of the case was achieved by the conventional osteotomy techniques at final operation. The maxilla was successfully advanced to the desired position producing good occlusion and an improved facial profile.     

Mandibular lengthening by distraction osteogenesis in children--a one-year follow-up study.

OBJECTIVE: The present study was undertaken to document whether mandibular length could be increased by distraction osteogenesis in children and what happens to the mandibular position 1 year after the distraction. METHODS: Five patients with hemifacial microsomia (four unilateral, one bilateral) had distraction osteogenesis performed to lengthen the mandible. All patients had cephalometric and panoramic radiographs obtained before and 3, 6, and 12 months after the distraction osteogenesis. RESULTS: The total mandibular length (Co-Gn) on the affected side was increased by 11.2 mm after the distraction and remained stable during a 1-year observation period. However, the increased mandibular length tended to move the chin downward (8 mm) more than forward (2 mm) during the same period. CONCLUSIONS: Distraction osteogensis can be used to lengthen the hypoplastic mandible. However, most of the increased mandibular length moved the chin downward more than forward.     

Piezoelectric distraction osteogenesis in the atrophic maxillary anterior area: a case report

The reconstruction of a maxillary anterior dentoalveolar defect in patients with trauma has been a challenge for surgeons. Extensive loss of bone and teeth in the anterior maxilla presents a complex problem for reconstruction. This is owing to the difficulty in achieving complete closure using overlying soft tissue. Tension-free sutures cannot be used after a large bone graft because the overlying soft tissue on severe bone defects of the anterior maxilla is often deficient and is attached to the underlying atrophic bone by scarring. Distraction osteogenesis provides a method to regain both hard tissue and soft tissue without any grafting. We describe a patient who had severe maxillary anterior bony defects that were restored by means of piezoelectric distraction osteogenesis, followed by dental implant placement. Clinical, radiological, and histological results showed that the reconstruction was successful.