Endoscopically assisted intraoral mandibular distraction osteogenesis

Correct placement of intraoral devices for mandibular distraction osteogenesis is important to achieve the ideal vector of distraction. As visual inspection and intraoperative management in the inferior mandibular border or at the posterior ascending ramus is impaired, an endoscopically assisted method is presented. Since the introduction of this new technique operation time and ease have been significantly improved.     

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.     

Spring-mediated mandibular distraction osteogenesis

Successful performance of distraction osteogenesis requires rigorous patient compliance with a daily activation regimen of a percutaneous screw. Previous clinical studies have found that failure of patient compliance with this regimen is the most common complication leading to technical failure of the distraction process. The authors have developed an internalized spring-mediated device for mandibular distraction osteogenesis that can potentially abrogate the risks associated with patient compliance by allowing for automated distraction across an osteotomy. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A segment of nickel-titanium shape memory alloy reinforced at both ends with a pinball was fashioned into an inferiorly based arc and secured to the mandible with stainless steel wire. On postoperative day 12, spring activation commenced by cutting a wire binding the two pinballs to one another. Animals were observed for 6 weeks before they were killed. Radiographic studies and decalcified histologic analysis were performed on extracted mandibles. Temperature- and displacement-dependent properties of the shape memory alloy were also examined. Five animals were excluded from the study due to infection, nonunion, or device failure. A mean distraction of 1.2 mm in the distracted hemimandible relative to the nonoperated hemimandible was found (P <.001, two-tailed paired t test). The maximum distraction achieved in an experimental specimen using the spring distractor was 3.7 mm. There were no other histologic or radiographic differences found between study specimens and specimens subjected to traditional distraction methods. Biomechanical testing of the shape memory alloy revealed a temperature-dependent increase in force at body temperature compared with room temperature and a reduction in force with increased displacement of the spring. This study demonstrates the feasibility of spring-mediated distraction osteogenesis across an osteotomy. As the field of distraction osteogenesis matures, the next level of sophistication in the clinical development of devices will incorporate technology that permits fully internalized and automated distraction to occur.     

Intraoral mandibular distraction osteogenesis

During recent years, distraction osteogenesis has gained in popularity for the treatment of various bone deficiencies either in the vertical, transverse, or anteroposterior dimension. Distraction osteogenesis has been shown to be an effective technique for mandibular widening and lengthening where traditional orthognathic surgery has important limitations. The intraoral approach to these procedures prevents damage to the inferior alveolar nerve and the developing dental follicles, and eliminates hypertrophic facial scars. Intraoral distraction osteogenesis also avoids donor-site morbidity, and minimizes the need for blood transfusion or prolonged fixation. This intraoral application provides for enhanced patient acceptance and reduces the potentially negative psychosocial effects of wearing an extraoral distraction appliance.     

Mandibular widening by intraoral distraction osteogenesis

Transverse mandibular deficiency with crowding of the mandibular anterior teeth is frequently present in patients with Class I and II malocclusions. The hallmarks of treatment by compensating orthodontics, functional appliances or orthopaedic devices are instability, compromised periodontium and compromised facial aesthetics. A new surgical technique has been developed to widen the mandible. The method is based upon gradual osteodistraction following vertical interdental symphyseal osteotomy. Ten patients with transverse mandibular deficiency and significant dental crowding were treated by symphyseal distraction and subsequent non-extraction decompensating orthodontic treatment. Either an intraoral tooth-borne Hyrax appliance or a new custom-made bone-borne osteodistractor was used to gradually widen the mandible. The surgical procedures were accomplished under local anaesthesia and intravenous sedation in an ambulatory surgical setting using an individualized distraction protocol. The appliances were activated 7 days after symphyseal osteotomies, once each day at a rate of 1 mm per day and stabilized for 30–60 days after distraction. After the segments were distracted, non-extraction orthodontic alignment of the mandibular anterior teeth was accomplished. The symphyseal distraction gaps were bridged by new bony regenerate. Distraction osteogenesis provided an efficient surgical alternative to orthognathic surgery for widening the mandible and treatment of transverse mandibular deficiency without extraction of teeth.     

Mandibular distraction osteogenesis by sagittal split osteotomy and intraoral curvilinear distraction

Mandibular distraction combining the sagittal split ramus osteotomy and an intraoral curved distractor is efficacious to lengthen the mandibular body and ramus. The sagittal split permits immediate rotation of the proximal segment and lengthening while still providing a large surface interface for regenerative bone. The buried curved distractor enables mandibular lengthening along the normal logarithmic grow spiral as shown by Moss and Rickets. In addition, it is well tolerated by the patient and can remain in place for a long duration to provide support. In summary, this combination of surgical techniques provides certain advantages for distraction of the mandible.     

A mathematical model for mandibular distraction osteogenesis.

In this paper, we look at the mechanobiological processes involved in mandibular distraction and, as a first approximation, propose an elastoplastic uniaxial model.     

Low-level laser effect on mandibular distraction osteogenesis.

PURPOSE: The purpose of this study was to determine whether low-level laser (LLL) application during distraction osteogenesis could accelerate bone regeneration and decrease the length of the consolidation phase and thereby reduce potential patient morbidity. MATERIALS AND METHODS: Nine adult female New Zealand white rabbits underwent bilateral mandibular corticotomies and placement of unidirectional distraction devices (KLS-Martin LP, Jacksonville, FL). Each rabbit served as its own internal control. After a latency of 1 day, distraction progressed bilaterally at 1 mm per day for 10 days. Immediately after each device activation, the experimental side, chosen randomly, was treated with real LLL (Laser Medical Systems, Hedehusene, Denmark) of 6.0 J x 6 transmucosal sites in the area of the distraction gap. Radiographs were taken presurgically, immediately postsurgically, and weekly until sacrifice, and the bone was analyzed using a semiquantitative 4-point scale (Bone Healing Score [BHS]). Three animals each were sacrificed at 2, 4, and 6 weeks postdistraction, and each hemimandible was prepared for histologic examination in a blinded fashion. RESULTS: Ten millimeters of distraction was achieved in each rabbit bilaterally. Radiographically, the BHS was higher for the LLL-treated group at all time periods. Histologically, the area of new bone trabeculation and ossification was more advanced for the LLL-treated group, with less intervening fibrovascular intermediate zone in the bony regenerate, at all time periods. The formation of a complete inferior border occurred sooner in the treatment group than in the controls. CONCLUSIONS: LLL accelerates the process of bone regeneration during the consolidation phase after distraction osteogenesis. The adjunctive use of LLL may allow a shortened period of consolidation and therefore permit earlier device removal, with the avoidance of morbidity associated with prolonged device retention.     

Osteoclastogenic activity during mandibular distraction osteogenesis

Mandibular distraction osteogenesis is a well-developed clinical modality for the treatment of craniofacial deformities and dental arch discrepancies, in combination with orthodontic treatment. However, in our previous study, orthodontic tooth movement into the distraction gap caused severe root resorption. The present study aimed to clarify the osteoclastogenic activity of cells in the distraction gap. We hypothesized that the gene expression of osteoclastogenic- and osteoclast-supporting molecules in osteoblasts and stromal cells would increase at distraction sites during the consolidation period. An animal model experiment involving rabbits was designed for mandibular distraction osteogenesis and subjected to in situ hybridization analysis. The number of osteoclasts was larger in the distraction gap during the early consolidation period than in normal controls, due to an increase of gene expression for osteoclastogenic cytokines in osteoblasts. It was concluded that osteoclastogenic and osteoclastic activities are stimulated at distraction sites during the early consolidation period.     

Unilateral mandibular widening with distraction osteogenesis

Mandibular widening with distraction osteogenesis (DO) has been shown to be an acceptable and stable treatment modality. Mandibular widening with DO is useful in relieving crowding and for restoring a rotated mandibular arch segment to its original condition. This is especially true when a patient has a unilateral medial displacement of the proximal segment of the mandible or a unilateral Brodie bite. This case report shows the application of mandibular widening with DO for skeletal reconstruction and prosthodontic preparation in a patient with unilateral medial displacement of the proximal segment of the mandible. The design of the osteotomy line and the placement of the distractor must be taken into consideration in a detailed procedure for unilateral mandibular widening of the mandible.     

牵引成骨技术在下颌骨节段性缺损修复中的应用

20世纪90年代，基于Ilizarov的长期研究成果，牵引成骨(distraction osteogenesis，DO)技术在颌面外科领域得到重要发展，早在1973年Snyder等报告了下颌骨缺损的DO修复实验，Shwyrkow和Shamsudinov最早将其应用于临床缺损病例。DO修复节段性下颌骨缺损的具体方式可分为3种：骨传送、加压．牵引骨形成、骨移植后矫形。     

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.     

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.     

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。     

Analysis of skeletal movements in mandibular distraction osteogenesis.

PURPOSE: The purpose of this study was to use geometric parameters of movement, calculated from 3-dimensional computed tomography (CT) data, to determine the curvilinear distractor dimensions required to correct mandibular deformities in a series of patients. MATERIALS AND METHODS: Preoperative CT scans from 15 patients with symmetric (n = 5) and asymmetric (n = 10) deformities were imported into a CT-based software program (Osteoplan; an open-source visualization application developed by Gering et al at the Surgical Planning Laboratory [SPL, Brigham and Womens Hospital, Boston, MA]). The software was used to reconstruct virtual 3-dimensional models from these scans. Two experienced surgeons, working with a computer scientist, then used Osteoplan to create an ideal treatment plan for each patient. In each case, the 3-dimensional curvilinear movement was quantified using 4 "parameters of movement" (POMs). These parameters were then used to prescribe a distraction device capable of executing the planned skeletal correction. Curvilinear distractor dimensions calculated by Osteoplan included the radius of curvature of the prescribed device, and the distractor elongation, pitch, and handedness. RESULTS: Treatment plans including POMs were developed for each patient. The radii of curvature for the prescribed distractors ranged from 2.3 to 14.1 cm, the distractor elongation dimensions ranged from 0.7 to 3.2 cm, and the pitch (horizontal plane) dimensions ranged from 0.005 to 0.8 cm. Handedness was either a left (n = 12) or right (n = 8) turning helix. CONCLUSION: The results of this study indicate that, using geometric parameters of movement calculated from 3-dimensional CT scans, curvilinear devices could be prescribed for correction of the range of skeletal deformities in this group of patients.     

Effect of electrical stimulation on mandibular distraction osteogenesis.

This study was designed to examine whether the use of electrical stimulation during mandibular lengthening accelerates new bone formation. Twenty adult female rabbits weighing between 2800 g and 3200 g underwent left mandibular body osteotomy. After a 3 day latency period, an external fixation device was activated at a rate of 0.7 mm per day for 10 days. Direct current electrical stimulation of 10 microA was applied to 10 rabbit mandibles. Two of the screws were used as electrodes during the distraction phase. The other 10 rabbits (control group) were not stimulated. The device was then stabilized for periods of 10, 20, 30 and 60 days in both groups. The distraction segment was evaluated radiographically by assessing the proportion of bone mineral density using a dichroma scan. The amount of new bone formation was studied histologically with an image analyzer to evaluate the bone formation in the distraction gap. Histological examination showed that the new bone formation 10 and 20 days after distraction was greater in the electrical stimulation group than in the control group. Ten and 20 days after distraction, image analysis and analysis of bone mineral density in areas of newly formed bone indicated that there was a greater amount of new bone formation in the stimulation group than in the control group. The radiographic evaluation, however, did not demonstrate significantly different images between the stimulation group and the control group. Thirty and 60 days after distraction, no difference in the amount of new bone formation was noted in either the experimental or the control groups. These results indicate that electrical stimulation during gradual distraction promotes new bone formation in the early retention period in a rabbit model.