牙支抗羊下颌骨牵张成骨的组织学观察

目的：用自制的牙支抗骨延长装置进行羊下颌骨延长的实验研究，观察其组织学特征。方法：将9只7～9月龄山羊，实验组分4组，每组2只，对照组1只，在下颌第2和第3前磨牙之间行骨皮质切开术后，将自制的颌骨延长装置黏固于牙齿之上，术后5d开始加力，每次0．25mm，2次／d。在开始加力后分别于8、16、32、48d时将动物处死，标本进行四环素荧光标记检查、HE染色及Mallory三色染色观察。结果：四环素荧光标记结果显示：存延长区域内有黄绿色荧光标记的新骨形成；HE染色及Mallory三色染色结果显示：新骨从牵引区两侧逐渐向中央延伸，融合后的骨小梁逐渐改建成熟，纤维束、新形成的骨小梁以及早期的各种细胞均表现为长轴与牵引力的方向一致。结论：新骨有沿着牵引力方向形成与改建的组织学特点：     

Unilateral mandibular ramus elongation by intraoral distraction osteogenesis

Successful correction of facial asymmetry by mandibular distraction osteogenesis relies on mastering vector control. Lack of necessary vector control continues to compromise the treatment modality. The purpose of this study was to describe a new simplified method for vector transfer and to evaluate this method according to the outcome and the efficacy of distraction osteogenesis in the correction of unilateral mandibular hypoplasia and asymmetry. Twenty-seven patients with unilateral hypoplasia of the mandibular ramus underwent unilateral mandibular distraction osteogenesis with intraoral distraction devices. Posterior-anterior and lateral cephalograms were analyzed by digitalization. Changes in sagittal, vertical, and transversal linear and angular dimensions after the distraction treatment were evaluated by measurements performed on headfilms taken before and after surgery. Means and variances were calculated for selected cephalometric variables for each time point. The differences between the control and the treatment side were calculated, statistically described, and compared with a paired Student t test. Correction of the mandibular asymmetry, chin position, and the canting of the occlusal plane was obtained in all patients clinically, as well as radiographically, by the use of intraoral unidirectional distraction osteogenesis.     

MS-1型内置式下颌骨骨牵引延长器及其动物实验

目的：报告自行研究开发的内置式下颌骨骨牵引延长器,探讨其用于动物实验的可行性。方法：１５只犬采用ＭＳ－１型下颌骨牵引延长器,并进行单、双侧下颌骨体部牵引延长２０ｍｍ,并进行Ｘ线与组织学观察。结果：实验犬下颌骨牵引延长效果肯定,器械均未见断裂或松动变形,牵引区成骨明显。结论：ＭＳ－１型内置式牵引器具有临床应用可能性。     

Soft tissue changes during distraction osteogenesis

This study aimed to investigate soft tissue changes in distraction osteogenesis depending on various distraction and consolidation periods. Fifteen male rabbits were divided into three groups and evaluated for five parameters. An external custom-made device was placed on the right side of the mandible. The postoperative latent period was 4 days. The groups were distracted for different periods (6 days, 3 mm; 11 days, 5.5 mm, 16 days, 8 mm). For histomorphometric analyses, specimens were retrieved from both study and control sides of the mandible and were examined with light microscopy. The number of muscle fibres and nuclei on the study side increase proportionally with the distraction period. Regeneration in the first group continued in its natural pattern; in the second group, there seemed to be degeneration rather than regeneration; and in the third group there seemed to be a balance between regeneration and degeneration processes. In conclusion, when a massive amount of bone is to be obtained, instead of distracting the bone at once, it is thought to give better results if the total amount of distraction is divided into several time periods.     

Soft tissue response to mandibular advancement using 3D CBCT scanning

This prospective longitudinal study assessed the 3D soft tissue changes following mandibular advancement surgery. Cranial base registration was performed for superimposition of virtual models built from cone beam computed tomography (CBCT) volumes. Displacements at the soft and hard tissue chin (n = 20), lower incisors and lower lip (n = 21) were computed for presurgery to splint removal (4-6-week surgical outcome), presurgery to 1 year postsurgery (1-year surgical outcome), and splint removal to 1 year postsurgery (postsurgical adaptation). Qualitative evaluations of color maps illustrated the surgical changes and postsurgical adaptations, but only the lower lip showed statistically significant postsurgical adaptations. Soft and hard tissue chin changes were significantly correlated for each of the intervals evaluated: presurgery to splint removal (r = 0.92), presurgery to 1 year postsurgery (r = 0.86), and splint removal to 1 year postsurgery (r = 0.77). A statistically significant correlation between lower incisor and lower lip was found only between presurgery and 1 year postsurgery (r = 0.55). At 1 year after surgery, 31% of the lower lip changes were explained by changes in the lower incisor position while 73% of the soft tissue chin changes were explained by the hard chin. This study suggests that 3D soft tissue response to mandibular advancement surgery is markedly variable.     

Distraction osteogenesis for mandibular advancement

The purpose of this study was to investigate the possibilities of distraction osteogenesis to correct mandibular hypoplasia. Fourteen young patients (mean age 14.1 years) with a proven resistance to initial, functional orthodontic therapy, were treated by means of bilateral intraoral distractors. The corticotomy was performed in the region of the third molar. The latency time was six days and the stabilization period six weeks. In all cases the planned lengthening of the mandible and class 1 occlusion were achieved. Seven patients required additional elastic band traction to close a mild open-bite directly after active distraction. In the first seven patients, insufficient mobilization at the site of the corticotomy had resulted in a broken distraction rod in two patients and incomplete distraction of the lingual cortex in one patient. Adequate mobilization at the site of the corticotomy prevented these problems in later cases. No permanent sensory disturbances were seen. Twelve patients finished their orthodontic treatment within six months after distraction.     

Maxillary advancement using distraction osteogenesis with intraoral device

This article describes the surgical orthodontic treatment of maxillary hypoplasia in a patient with cleft lip and palate using maxillary distraction osteogenesis with internal maxillary distractors. Maxillary advancement was performed to correct the retrusive maxillary facial profile and Class III malocclusion. Rotational movement of the distraction segment was made to correct the upper dental midline. Although maxillary advancement was insufficient because of unexpected breakage of the intraoral distractor after completion of the distraction, skeletal traction with a face mask compensated for the shortage. Successful esthetic improvement and posttreatment occlusal stability were achieved with no discernible relapse after 2 years of retention.     

Soft tissue response to mandibular advancement and genioplasty.

Changes in facial esthetics after orthognathic surgery should be predictable if the results are to be satisfactory. The skeletal elements are moved in a planned and controlled manner, but the soft tissue drape is not as precisely managed. This study was on 31 patients who had undergone a mandibular advancement by means of a sagittal split osteotomy, 17 of whom had also received an advancement genioplasty and 6 received a maxillary impaction. The results showed a consistent 1:1 ratio of soft to hard tissue advancement at pogonion and B point, and that predictions could be accurate in both anteroposterior and vertical directions. When a genioplasty was added to the advancement, however, the results were much less consistent. The mean ratio was 0.9:1 of soft tissue to skeletal movement at pogonion, but the average difference between hard and soft tissue movement was +/- 2.6 mm. Thus the prediction of anteroposterior soft tissue changes was quite inaccurate. Changes in the vertical dimension were also more marked in the genioplasty group. The lower lip also showed a variable response, particularly in the genioplasty group, where the mean ratio was 0.5 mm lip advancement per 1.0 mm skeletal change, but again a range of 4.0 mm in either direction. There were no meaningful changes 1 year after surgery.     

牙支抗进行羊下颌骨延长的初步实验研究

目的：观察自制的牙支抗骨延长装置进行羊下颌骨延长的实用性和有效性。方法：将8只7－9月龄羊分为4组,每组2只,在下颌第2和第3前磨牙之间行骨皮质切开并造成青枝骨折后,将自制的颌骨延长装置粘固于牙齿上,术后5天开始加力,每次0．25mm,每日2次,在开始加力后分别于第8,第16,32,48天时将动物处死,标本进行大体观察,血管造影,X线检查。结果：大体标本显示,在下凳第2,第3前磨牙之间出现明显的骨延长区域。其表面由正常的牙龈组织覆盖。X线检查结果表明随着时间的延长,新骨不断形成并趋于成熟,加力结束后保持16天的标本丁颌骨连续性就已恢复,支抗基牙有所倾斜,周围其他组织未见明显不良反应。血管[造影显示,在骨延长的各个阶段,下齿槽动脉通畅良好,结论 ：利用这种牙支抗的骨延长装置能够有效地进行下颌骨的延长。     

Complications in bilateral mandibular distraction osteogenesis using internal devices

OBJECTIVE: We sought to evaluate the possibility of distraction osteogenesis as an alternative to conventional bilateral sagittal split osteotomy. Complications (intraoperative, intradistraction, and postdistraction) were evaluated retrospectively. STUDY DESIGN: Seventy consecutive patients (40 males and 30 females, 11.2-37.3 years old; mean, 14.2 years) underwent distraction osteogenesis to lengthen the mandible. The surgical procedure was carried out with the patient under general anesthesia. After the osteotomy was performed, 2 intraoral monodirectional distraction devices were placed on the mandibular cortex in the third molar region. The rate of distraction was 1 mm/day. The different complications encountered during all phases of the distraction procedure were recorded. RESULTS: A total of 28 complications (40%) were recorded. In 10 patients (14.3%), the complications were technique- or device-related, or both, and occurred early in the learning period. Five patients (7.1%) had infection occur, and 3 patients (4.3%) had prolonged sensory loss in the distribution of the alveolar nerve. Severe complications occurred in 6 patients (8.6%). Rehospitalization was necessary in 5 patients (7.1%), 4 of whom (5.7% of the series) required further surgery under general anesthesia. CONCLUSION: Distraction osteogenesis can be considered a safe and predictable procedure for lengthening the mandible, with a low incidence of major complications. The infection rate and the incidence of damage to the inferior alveolar nerve (2.1%) are low. Compliance of both patients and parents during the whole treatment period is of the utmost importance.     

A custom-made distraction device for experimental mandibular distraction osteogenesis

Distraction osteogenesis has recently become popular in craniofacial reconstruction, after it was first described for long bones. Despite the widespread clinical use of this technique, currently, lack of an ideal experimental model for small animals hampers investigations focused on its molecular basis, which warrants further elucidation. The authors developed a new device for distraction of the rat mandible and, to asses its effectiveness, practiced on 30 animals assigned to either an acute 3-mm distraction group (n = 7) or a gradual distraction group (0.25 mm twice a day for 6 days; n = 23). The authors applied the devices to a localization that allowed them to perform the ostomies posterior to the molar teeth. Because of a U-shaped plate that the authors used for posterior pin fixation, their device maintained its stability until the end of the study, despite the delicate anatomy of the bone at the posterior part of the mandible. Additionally, the authors described a practical and easy method of transient mandibular stabilization method that facilitates the manipulations while the mouth is open for safer airway control during surgery. This new nutrition technique with enteral feeding solution solved the problem of progressive weight loss after surgery. Application of the device was easy and practical, without demanding complex manipulations. The authors did not observe any device dislodgement or a high rate of accidental fractures during the manipulations. They demonstrated that the device works properly and is able to create ossified regenerate bones that fill the entire distraction gap, which can be used for various investigations during distraction osteogenesis.     

Mandibular advancement by distraction osteogenesis for tracheostomy-dependent children with severe micrognathia.

PURPOSE: The purpose of this study was to evaluate mandibular lengthening by distraction osteogenesis (DO) to achieve decannulation of micrognathic children with "permanent" tracheostomies. PATIENTS AND METHODS: Using a retrospective chart review, patients were included who had 1 ) airway compromise/tracheostomy, 2 ) micrognathia, 3 ) polysomnography-documented obstructive apnea, and 4 ) mandibular advancement using DO. Excluded were 1 ) adults, 2 ) neonates without tracheostomy, and 3 ) patients with central apnea. Patient age, past medical history, age at tracheostomy, and distraction protocol were documented. Oxygen saturation, posterior airway space (in millimeters), and sella-nasion-B point (SNB) angle were recorded. The distraction protocol consisted of a latency of 48 hours and a rate of 1 mm/day. RESULTS: There were 5 children, aged 2 to 14 years, who received a tracheostomy between ages 2 and 36 months for airway obstruction. All patients underwent bilateral mandibular distraction using semiburied, unidirectional devices. The average latency was 58 hours, the rate was 1 mm/day, the duration of fixation was 40 to 60 days, and the magnitude of advancement was 23 mm. Healing was evaluated by clinical, radiologic, and ultrasound examinations. No complications were experienced. Mean follow-up was 3.2 years. Postdistraction sleep studies demonstrated no obstructive apneic events and a mean oxygen saturation of 98% (preoperative, 76%, P < .005). Cephalometric values improved: posterior airway space 4 to 14 mm; SNB 66 degrees to 72 degrees ( P < .005 for both variables). Four of the 5 patients have been successfully decannulated to date. CONCLUSIONS: The results of this preliminary study indicate that mandibular advancement by DO is a potentially viable treatment option for tracheostomy-dependent children with upper airway obstruction secondary to micrognathia.     

Stability of mandibular advancement procedures: bilateral sagittal split osteotomy versus distraction osteogenesis

The aim of this study was to compare the postoperative stability of the mandible after a bilateral lengthening procedure, either by bilateral sagittal split osteotomy (BSSO) or distraction osteogenesis (DOG). All patients who underwent mandibular advancement surgery between March 2001 and June 2004 were evaluated; 26 patients in the BSSO group and 27 patients in the DOG group were included. The decision to use the intraoral distraction or BSSO for mandibular advancement primarily depended on the patient's choice. In both groups, standardized cephalometric radiographs were taken preoperatively, postoperatively (BSSO group) or directly post-distraction (DOG group) and during the last study measurement in May 2005. The cephalometric analysis was performed using the following measurements: Sella/Nasion-Mandibular point B and Sella/Nasion-Mandibular Plane. Point B was used to estimate relapse. This study showed no significant difference in relapse between the BSSO and the DOG group measured 10-49 months after advancement of the mandible (p>0.05). There is no postoperative difference in the stability between BSSO and DOG after mandibular advancement after 1 year.     

两、三焦点牵张成骨在下颌骨缺损修复中的应用

目的：通过两焦点、三焦点对山羊下颌骨缺损进行牵张,比较两种牵张成骨方式的新骨成骨量。方法：将8只成年山羊随机分成两组,每组4只,分别采用两焦点和三焦点牵张成骨术进行骨缺损修复。牵张结束后固定8周,处死动物取牵张区新生骨组织标本进行X线检查、组织学检查、骨密度分析。结果：两实验组牵张区新骨生长的质无明显区别,在量的比较上,三焦点组X线检查、组织学检查、骨密度测定的结果均好于两焦点组,骨密度测定分析结果有统计学意义（P〈0.05）。结论：三焦点牵张成骨在大面积颌骨缺损的修复中新骨的成骨量好于两焦点牵张成骨组。     

两焦点与三焦点牵张成骨方式在下颌骨缺损修复中的应用

目的对山羊下颌骨缺损进行两焦点与三焦点牵张,比较两种方式的新骨成骨量。方法将8只成年山羊随机分成两组,每组4只,分别采用两焦点和三焦点牵张成骨术来进行骨缺损修复。牵张结束后固定8周后处死两组动物取牵张区新生骨组织标本进行X线、组织学、骨密度分析。结果两组牵张区均有新骨形成,质无明显区别,在量的比较上,三焦点组X线、组织学、骨密度测定的结果均优于两焦点组,骨密度测定分析结果有统计学意义(P<0.05)。结论三焦点牵张成骨在大面积颌骨缺损的修复中新骨的成骨量优于两焦点牵张成骨。     

Proximal segment displacement in mandibular distraction osteogenesis

Distraction osteogenesis has been advocated for treatment of the mandibular deformity in patients with hemifacial microsomia (HFM). During the active phase, the force of distraction pushes the distal segment of the mandible down, creating a distraction gap. Because of the abnormal temporomandibular joint anatomy in HFM patients, the proximal segment may not seat in the glenoid fossa and thus may be displaced with distraction. The purpose of this study was to determine the vector(s) of proximal segment movement during mandibular distraction using a semiburied device. Two investigators traced the immediate pre-and postdistraction panoramic radiographs of 12 HFM patients (mean age at operation = 8.4 years, mean distraction = 28 mm) who had mandibular distraction with a semiburied device. Radiographic analysis, based on a vertical maxillary reference line, measured change in condylar position with angular and linear measurements. Inter-rater reliability for the tracing and analysis was shown with a correlation coefficient between 0.89 and 0.99 for all measures. Based on the angular and linear measurements, 10 of the 12 patients had superior movement of the proximal segment with distraction. Sagittal movement of the proximal segment could not be judged adequately. This study was based on measurements made on panoramic radiographs. Direct measurements could not be made; thus, it was not possible to estimate proximal segment movement in millimeters or as a percentage of total movement. Further studies to document proximal segment movement using computed tomography scans may provide more quantitative data.     

Model surgery prediction for mandibular midline distraction osteogenesis

Mandibular midline distraction osteogenesis is available as a treatment option for the correction of mandibular transverse arch deficiency. A model surgery technique is presented here through a case report that will allow the surgeon to predict the amount of transverse expansion that can be gained by this procedure. Utilizing measurements from a three-dimensional stereolithography model, the mandibular cast is mounted on a semi-adjustable articulator. The maxillary model is mounted onto the articulator using an interocclusal record. Acrylic straps are fabricated that relate the condylar elements of the articulator to the right and left mandibular dental segments. The mandibular model is sectioned at the midline, the hemi-mandibular segments are rotated laterally until the desired midline expansion is achieved and the mandibular model is luted into its new position. The post-expansion relationship of the maxillary and mandibular arches can be visualized on the articulator and provide useful information to the surgeon and orthodontist.