Treatment of temporomandibular joint ankylosis and facial asymmetry with bidirectional transport distraction osteogenesis technique

Transport distraction technique is a good treatment modality for unilateral temporomandibular joint ankylosis. However, with a unidirectional distraction, it is not possible to correct facial asymmetry that results from mandibular hypoplasia associated with early-onset unilateral temporomandibular joint ankylosis. For this purpose, gap arthroplasty and simultaneous bidirectional transport distraction was used to correct these deformities. Although vertical distraction corrects vertical deficiency of the ramus and creates a neocondyle, the simultaneous anteroposterior distraction of the transport segment corrects facial asymmetry resulting from horizontal shortness of mandible. Three patients, whose mean mouth opening was 8.6 mm, were successfully treated with this technique. Mean advancements in vertical and anteroposterior direction were 14.7 and 7.7 mm, respectively. Mean maximal mouth opening was 29.7 mm postoperatively. The average follow-up period was 13 months (range, 12-15 mo). During this period, reankylosis was not observed, and the interincisal distance did not decrease. Gap arthroplasty and bidirectional transport distraction of the mandibular ramus is a good and effective therapeutic option in treatment.     

Review of devices for distractionosteogenesis of the craniofacial complex

Over the last 50 years, Ilizarov refined a method to successfully lengthen endochondral bones and the surrounding soft tissue matrix. Given the difficulties in reconstructing deformities of the craniofacial complex, distraction osteogenesis has recently been used to avoid the problems associated with conventional surgery and to begin correction at an earlier age. Distraction devices can be categorized by whether they are internal or external, the direction of distraction, and the site of application. External devices are capable of either unidirectional, bidirectional, or multiplanar (three-dimensional) distraction. Internal or intraoral distractors are capable of unidirectional distraction only. Distraction devices used to lengthen the mandibular ramus and body, widen the mandible, augment the alveolar ridge, conduct bone transport, and advance the midface are reviewed.     

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.     

Bidirektionale und unidirektionale Distraktion von Alveolarfortsatzdefekten

Aim

The purpose of the retrospective study was to compare bidirectional distraction osteogenesis with the currently used unidirectional method of alveolar ridge distraction with regard to bone height attained and complications.

Patients and methods

Overall 21 patients were treated by distraction osteogenesis for localized defects of the alveolar ridge. Vertical augmentation of the mandible and maxilla was performed using 10 unidirectional (group A) and 12 bidirectional (group B) devices. The effect of therapy was evaluated by height of bone gain and observed complications.

Results

The average gain of vertical bone height was approximately 6 mm. No statistically significant differences occurred between the two treatment groups (p=0.09). For the entire study two complications were observed: beside breakage of a distractor device (unidirectional distraction) an infection during the retention time (bidirectional distraction) developed.

Conclusions

It could be shown that osteodistraction is a potentially valuable therapy for the correction of alveolar defects. We observed complications in both groups. No statistical differences were noted in regard to gained bone height and complications between the two groups.     

Orthodontic management of the patientundergoing mandibular distraction osteogenesis

Distraction osteogenesis is a gradual incremental bone-lengthening technique that requires very precise treatment planning and surgical execution. Subtle variation in the position of the corticotomy/osteotomy or in the position of the distraction device will affect the ultimate position of the tooth-bearing (distal) segment. Other functional and/or anatomic factors (that at this time are not well understood) also have an influence on the direction in which the tooth-bearing segment moves during distraction. These factors combine to create a discrepancy between the planned direction and the actual or observed direction of distraction. The charge for the orthodontist is to plan, as carefully as possible and in concert with the surgeon, the direction (vector) in which the tooth-bearing segment will travel during distraction. Further, the orthodontist must be able to modify the position that the tooth-bearing segment takes by exerting orthopedic and orthodontic forces and by making adjustments to the distraction device. In addition, the orthodontist must prepare the dentition before distraction, manage the dentition during distraction, and finish the occlusion after distraction in a manner that is different from more traditional jaw-respositioning techniques.     

Distraction osteogenesis in an anterior mandibular bone defect utilizing lingual periosteal release: a case report

This clinical report presents a modified distraction technique to achieve height in the vector of distraction. The success of distraction osteogenesis depends on both biologic and biomechanical factors. The focus in this case is on correcting the direction of distraction; incorrect distraction direction is a frequent complication associated with distraction osteogenesis in the mandible. A 21-year-old man presented with a 10-mm vertical bone defect in the anterior mandible caused by facial trauma. The treatment chosen was distraction osteogenesis. After osteotomizing a bone segment and slitting the lingual periosteum, the bone segment was advanced anteriorly 4 mm and an extra-alveolar distraction device was applied. This approach allows the distraction device to be placed vertically, thus preventing lingual shift. The newly created alveolar ridge fully met prosthodontic requirements for a predictable outcome.     

Computer-aided surgery in distraction osteogenesis of the maxilla and mandible.

When using unidirectional intraoral distraction devices, it is desirable to be able to determine the final position of the bone fragment after the distraction procedure. However, additional constraining forces from adjacent tissues render the prediction of the distraction direction difficult. We have utilised computer-aided surgery in three patients for intraoperative control of the distraction direction. In one cleft palate patient, suffering from maxillary hypoplasia and anterior open bite, a modified Le Fort I osteotomy and maxillary distraction was performed. Despite a ventrocaudal position of the distraction device, intraoperative computer visualisation showed an unfavourable caudal vector of distraction without any anterior movement. The final result confirmed the direction indicated by the computer. Maxillary advancement remained insufficient. In two patients suffering from mandibular hypoplasia, intraoperative assessment revealed a favourable direction of distraction. The distraction procedure led to a satisfactory result in both cases. Computer-aided surgery is helpful in assessing the vector of distraction intraoperatively, making the result of the distraction procedure more predictable and allowing instant correction by adequate reapplication of the device.     

牵张过程中下颌骨各区段血流量时相变化的定量研究

目的：^99mTc核素闪烁扫描术定量检测下颌骨牵张过程中各区段血流量的时相变化.方法：用自制口外牵张器延长12只成年雄性山羊的双侧下颌骨,于术后第5、10、15、25、35、45天用^99mTc核素闪烁扫描术定量检测下颌骨各区段血流量.结果：在牵张过程中颌骨各区段血流量均有不同程度的增加.在牵张期牵张段和牵张区远心段血流量大幅度增加,而牵张区近心段血流量仅略有上升;在固定期牵张段和牵张区远心段血流量逐渐降低,但仍维持在较高水平,牵张区近心段血流量无明显减少.结论：牵张期使血流量增加效应的幅度增强、持续时间延长;血流量增加的主要原因之一是牵张区大量毛细血管新生.     

Reconstruction of maxillectomy defect by transport distraction osteogenesis

The study aimed to explore the feasibility of posterior maxillectomy reconstruction by transport distraction in a primate model. In each of 14 male adult rhesus monkeys, posterior partial maxillectomy was performed on one side of maxilla to create a posterior maxillary deflect. Immediately after the maxillectomy, a dentoalveolar segment anterior to the defect was osteotomized as transport segment and a custom-made transport distractor was fixed on the residual maxilla. After a latency period of 5 days, the distractor was activated 1 mm daily to move the transport segment backward to the defect. This process lasted about 2 weeks. The transport segment was allowed to consolidate and the animals were sacrificed at different defined intervals. Transport distraction was successful in six animals. Three other cases were completed with minor wound dehiscence and one had a small oro-antral fistula with subsequent maxillary sinusitis. New bone bridging the distraction gap was confirmed by radiography and histology in the animals completing distraction. Reconstruction of posterior maxillectomy defect is proven feasible by transport distraction osteogenesis.     

Bending of the distraction site during mandibular distraction osteogenesis in the rabbit: a model for studying segment control and side effects.

PURPOSE: The purpose of this investigation was to develop an animal model for studying and correcting mandibular distraction side effects. MATERIALS AND METHODS: Twenty-nine rabbits underwent bilateral mandibular distraction. Bending of the mandible was accomplished by offsetting a linear distraction by 35 degrees from the occlusal plane (4 screws per distractor), rotating the anterior segment inferiorly (2 screws per distractor), and removing a 3- or 6-mm wedge of the distraction site. The amount of bite opening varied according to the surgical design. Direct measurements, radiographs, and histology samples were compared. RESULTS: Linear distraction produced a 4-mm anterior open bite and a Class III malocclusion after 2 weeks of distraction. Segmental rotation produced an 8-mm anterior open bite without complications. Removal of a wedge initiated rotation of the anterior segment. A large wedge (6 mm) produced fibrous union in the distraction site. The amount of bite opening or closure depended on the number of surgical screws and position of the distractor. Serial histologic sections showed bone formation at the rotated, triangular distraction site. CONCLUSION: Bite opening or closure can occur from loss of segment control or by altering surgical design. This information is needed to counter unwanted side effects or to plan segment rotations.     

A customized distraction device for alveolar ridge augmentation and alignment of ankylosed teeth

The purpose of this study was to develop an extraosseous, tooth-supported miniature intraoral device that could produce prosthetically driven bone distraction of small atrophic alveolar ridge segments. Extraosseous distraction requires that the distraction device be anchored to a dental implant previously placed into the ridge according to its anatomic axis. A distractor can also correct the position of implants placed in young patients before skeletal growth is completed. Similarly, it allows the alignment of ankylosed teeth not treatable by orthodontics. The device is made of (1) an engine consisting of an orthodontic micrometric screw; (2) a joint between the implant and the engine, ie, the ball attachment/o-ring system; and (3) an anchorage system to the oral cavity provided by an orthodontic appliance and a mini-implant for possible additional support. Surgery involves an osteotomy of the atrophic alveolar ridge segment, incorporating the implant, from the basal bone; afterward the device can be applied and distraction of the segment can be carried out. Distraction was successfully performed in 3 clinical cases: 2 bone-implant segments and 1 bone-ankylosed tooth segment. All cases were clinically uneventful. This mini-device for osteogenic distraction of small atrophic ridge segments can provide for accurate and precise ridge augmentation, as is required for ideal prosthetic rehabilitation.     

Closure of vertical alveolar bone defects with guided horizontal distraction osteogenesis: an experimental study in pigs and first clinical results.

PURPOSE: To evaluate the option of treating alveolar clefts by guided distraction osteogenesis instead of applying osteoplasty with autologous bone grafts from iliac crest, rib or fibula. MATERIAL AND METHODS: At first, 30 land-bred pigs were operated upon. Treatment of each animal included creating bony defects measuring 2, 4 or 8 mm in the maxilla, anterior to the canine region and up to the nasal periosteum. In 15 of the 30 animals, a new horizontal segment distractor was tested. The device was placed in situ prior to creating an alveolar segment posterior to the defect. This segment was then transported gradually by distraction, thus crossing and closing the defect. At the end of the distraction and stabilization periods the newly formed bony tissue was examined. RESULTS: The critical size of defects was found to be larger than 4 mm. In five of six animals with a horizontal defect of 8 mm, complete ossification of the defect had occurred following distraction osteogenesis. This technique was then applied to five patients successfully. CONCLUSION: It was shown that distraction osteogenesis is a valid alternative for treating alveolar clefts.     

Treatment options in distraction osteogenesis therapy using a new bidirectional distractor system

PURPOSE: The purpose of this retrospective study was to compare a bidirectional distraction system with a unidirectional system with regard to bone height attained and the need for secondary graft procedures. MATERIALS AND METHODS: Unidirectional and bidirectional distractor devices were used for vertical augmentation of the maxilla and mandible in 2 separate groups of patients (n = 10 and n = 11, respectively). Clinical and radiographic outcome data were collected at postoperative follow-up examinations for up to 2.5 years. The height of the augmented alveolar ridge and the sagittal location of the bone fragment were measured on panoramic radiographs or lateral cephalograms. These data were analyzed with 1-way analysis of variance. Nonparametric data, such as treatment complications, were analyzed with the Fisher exact test. The dental implant survival data were evaluated with a Kaplan-Meier survival analysis. RESULTS: The difference in vertical bone gain observed between unidirectional and bidirectional groups (5.3 +/- 1.8 mm vs 6.1 +/- 2.3 mm) was not statistically significant. In the unidirectional group, additional autogenous bone grafting was required in 6 cases, while grafting was required in only 2 cases in the bidirectional group. This difference was due to the more precise control of the distraction process associated with the bidirectional distractor; however, it was not a statistically significant difference. Postaugmentation, 59 implants were placed in the augmented sites. These implants exhibited primary stability and were restored with good functional and esthetic results. CONCLUSIONS: The need for additional grafting procedures may be reduced in cases where the distraction vector is optimized, as generally seen with bidirectional distractor use.     

Vertical alveolar bone distraction at molar region using lag screw principle.

PURPOSE: Recently, alveolar bone distraction has been widely used and several devices have been developed for this purpose. However, there are some disadvantages in each device, especially for distraction of posterior alveolar ridge. The purpose of this study was to develop a new device for vertical alveolar bone distraction at the molar region and to show the results of its clinical application. MATERIALS AND METHODS: The mechanism of device is based on lag screw principle and the device consists of the following 4 components; distraction screw, hole implant fixture, supporting plate, and temporary short implant and/or neighboring natural teeth. The distraction screw suspended at the supporting plate is inserted into the internal thread of the hole implant fixture placed at alveolar transport segment. If the distraction screw turns at the supporting plate, the hole implant fixture with transport segment moves to the supporting plate without vertical movement of the screw at the supporting plate like a lag screw. After an animal experiment using 4 beagle dogs, the device was clinically applied in 4 patients before implant insertion. RESULTS: The distraction of the alveolar bone could be successfully performed in all patients without any complications. The direction of distraction with this device could be adjustable, and the alveolar bone could be distracted not only vertically but also horizontally. Moreover, the surgical technique is simple with no need for a second surgery, and there is no occlusal disturbance from the device. CONCLUSIONS: The new device for alveolar bone distraction using lag screw principle can be used effectively in the molar region.     

Distraction osteogenesis for augmenting the deficient alveolar ridge in preparation for dental implant placement: a case report

Distraction osteogenesis is a process in which new bone is created in a defect of the alveolar ridge by stretching existing bone. The process was originally developed by a Russian orthopedist, Gavriel Ilizarov, for the correction of long-bone deformities. It was later adapted to the maxillofacial skeleton and alveolar ridge. Distraction osteogenesis involves surgically creating a mobile bone segment to which a distraction device is attached. By controlled movement, the bone segment, along with the soft tissues overlying it, are transported into a new position. After a suitable healing period, the distraction device is removed and dental implants can be placed. A case report is presented describing the use of alveolar distraction to augment a vertically deficient alveolar ridge.     

Effect of extraosseous devices designed for vertical distraction of extreme resorbed mandibles on backward rotation of upper bone segments

We studied the result of vertical distraction osteogenesis in 34 patients as a method of restoring vertical bone height in atrophic mandibles. Cephalometric radiographs were obtained preoperatively, immediately after the installation of the distractor, at the end of the active distraction period (1-2 weeks), before placement of implants, after a consolidation period of 12 weeks, and annually thereafter. Particular attention was paid to the changed position of the upper segment in relation to the basal segment, compared with before and after active distraction. To monitor the position of the distracted upper bone segment, both the improvement in bony height and the angle of the distracted upper bone segment were scored using the menton-pogonion line as a reference plane. Surprisingly in nearly all patients there was a backward rotation of the segment with lingual-tipping of the upper segment by a mean of 12 degrees that meant that in such cases only 87% of the maximum gain in bony height could be achieved. As a consequence of the backward tipping of the top of the distracted alveolar ridge, the position of the implants was also more lingually directed. However, in all cases sufficient bony volume was achieved to allow placement of implants. Distraction osteogenesis is a successful way of restoring atrophic mandibles to gain sufficient bony volume to allow placement of implants. However, the vector of distraction is unpredictable.     

Internal distraction osteogenesis with a unidirectional device for reconstruction of mandibular segmental defects.

PURPOSE: To present the authors' clinical experience with unidirectional internal distraction devices to reconstruct mandibular defects. PATIENTS AND METHODS: Five patients have been treated with mandibular distraction osteogenesis to reconstruct different acquired segmental defects. These mandibular defects (35 to 80 mm in length) were reconstructed by means of internal distraction devices with a transcutaneous activator. All the patients underwent complete resection of the affected bone and immediate placement of the distraction device on the remaining mandible. RESULTS: The results' analysis was based on clinical observation, postoperative radiographs, histopathologic findings and 3-dimensional computed tomographic scans. Successful distraction osteogenesis was achieved in 3 cases. In 1 case, extensive intraoral exposure of the device was observed, resulting in a failure of the procedure. One patient died of distant metastases 4 months after the resective surgery. CONCLUSION: Because of the limited number of cases, this study is preliminary. However, considering the good experimental and clinical results, this new technique offers an alternative for patients with segmental mandibular defects in which, because of local or general reasons, a more aggressive procedure should be avoided.     

Intraoral mandibular distraction osteogenesis: special attention to treatment planning.

PURPOSE: To demonstrate our experience using internal devices for unidirectional distraction osteogenesis in treating different mandibular hypoplasias (with or without maxillary deformities). An algorithmic table for diagnosis, and treatment planning is presented. PATIENTS AND METHODS: Twenty internal distraction devices were used in 16 patients with mandibular hypoplasia. Deficiency in length of the mandible was calculated on three-dimensional computed tomography scans. The device was activated by a transcutaneous pin on the fifth postoperative day. Distraction was achieved at rates of 0.5 mm/12 h. After a variable period of consolidation the devices were removed. Mean follow-up was 18 months. RESULTS: Successful distraction osteogenesis was achieved in all patients. No premature consolidation or pseudoarthrosis was observed. Improvement of facial aesthetics was produced in all cases. Final occlusion was excellent in those cases where no simultaneous maxillary deformity was present. Orthodontic treatment was applied in all cases. Results remained stable one year postoperatively. CONCLUSIONS: The occlusal results obtained in this series show that we can plan distraction as a definitive treatment in cases with isolated mandibular hypoplasia. When an additional maxillary deformity is present, mandibular distraction must be performed first if indicated, but a maxillary procedure will be necessary later.     

Mandibular distraction osteogenesis with multidirectional extraoral distraction device in hemifacial microsomia patients: three-dimensional treatment planning, prediction tracings, and case outcomes.

Distraction osteogenesis of the craniofacial skeleton with the use of several different types of distraction devices (i.e., extraoral, intraoral, unidirectional, multidirectional, and customized) have been documented. However, the details of treatment planning and the method of predicting the distraction of the mandible in patients with hemifacial microsomia have not been published previously. This paper presents a technique for (1) three-dimensional treatment planning for mandibular distraction, (2) three-dimensional prediction tracings with conventional radiographs (panoramic, lateral, and posterior-anterior cephalometric), and (3) correlating the treatment planning and clinical applications. Lastly, 2 patients with hemifacial microsomia planned and treated with this approach are reported.     

Horizontal alveolar distraction of the narrow maxillary ridge for implant placement

PURPOSE: The purpose of this report was to describe a surgical technique for performing horizontal alveolar distraction of the knife-edge maxillary ridge. PATIENT AND METHODS: The patient was a 17-year-old woman with atrophy of the alveolar rim in the anterior upper jaw, which had inadequate width for implant placement. The transport segment was constructed by the osteotomy of the labial cortex of the alveolus. A transport plate of a distractor (LEAD system; Stryker Leibinger, Kalamazoo, MI) was placed on the transport segment. The distraction rod was inserted horizontally, and put in contact with the palatal cortex at the top. A base plate was not placed. RESULTS: The alveolar distraction was successfully performed to gain 6.0 mm in width and 0.5 mm in height, allowing placement of three 14-mm implants. All the implants were integrated so as to support the prosthesis. CONCLUSIONS: Alveolar distraction can be useful for augmenting the narrow ridge horizontally and placement of implants.