Distraktionsosteogenese der Mandibula bei kraniofazialen Fehlbildungen

In recent years, lengthening the human mandible by distraction osteogenesis has become an accepted treatment to correct severe mandibular hypoplasia. Using intraoral unidirectional and extraoral bidirectional distraction devices we report about our experiences and results in the application of the bone distraction technique in four selected cases of syndromal disease, including various forms of mandibular hypoplastic malformations. The patients involved were a boy with Pierre Robin syndrome, a girl with unilateral facial hypoplasia in Goldenhar's syndrome, a case with Nager's syndrome, and a rare case of midline deficiency caused by partial deletion of chromosome 18 (18p-syndrome). The distraction period lasted from 6 to 30 days and new bone formation, ranging from 6 to 28 mm, was achieved.     

Maxillary sequels in labial-alveolar-velopalatine clefts. The role of orthognathic surgery

Maxillary hypoplasia is a common sequel in cleft lip and palate deformities. After primary surgery to close lip and palate, patients routinely need extensive treatment particularly orthodontic management. With this type of approach, maxillary hypoplasia is less frequent and severe and subsequent orthognathic surgery is efficient in most cases. Without the proper management maxillary hypoplasia may be severe and patients will need a modified management and specific revision. At the end of maxillar growth, the first aim of treatment is to achieve continuity of the maxillary arch with gingivoperiosteoplasty. The transversal insufficiency can then be treated by distraction osteogenesis. Orthodontic treatment should leave place for missing teeth.     

Maxillary sequelae in cleft patients. Causes of maxillary hypoplasia and possible prevention

Maxillary hypoplasia is frequently observed in cleft patients. Although maxillary retrusion can be a syndromic outcome, the growth failure is also a consequence of the primary surgery of the palate, alveolar cleft, or lip. In this article the authors analyze the impact of primary surgery on the maxillary growth failure and discuss on how to prevent this complication.     

Implant insertion in distracted bone for reconstruction after gunshot injury

Distraction osteogenesis is a tissue engineering technique with two clinical applications in maxillofacial surgery: alveolar distraction and basal bone distraction. Even if it appears to be a binding and major surgery, distraction osteogenesis applied to facial bone, and especially to the mandible, has the great advantage of producing a pluritissular reconstruction of ideal quality and quantity, suitable for the ultimate goal of dental implant rehabilitation management. This technique had some drawbacks due to technical constraints related to the material. Distraction osteogenesis is well placed in the armamentarium of reconstructive surgery techniques for bone defects caused by trauma or tumor. It allows rapid restoration of adequate physiological conditions for mandibular dental implant placement. We reviewed the various modifications of this technique.     

Maxillary distraction and implantology

Vertical alveolar distraction can be a useful surgical technique in preprosthetic reconstructive surgery, especially after failed autogenous onlay bone grafting. The main advantage of this technique is to allow expansion of both the bone and soft tissue. Through a case of vertical alveolar reconstruction by distraction osteogenesis and implant rehabilitation in a patient who had undergone two previously unsuccessful interposition bone graft procedures, this report illustrate the advantages of alveolar ridge augmentation by distraction osteogenesis.     

Mittelgesichtsdistraktion nach LeFort-III-Osteotomie bei kraniofazialen Dysmorphien

BACKGROUND: The success of LeFort III-osteotomy with concurrent advancement of the midface in cases of severe, midfacial hypoplasia is limited by the soft covering tissue of the facial skeleton. There appear to be significant advantages in using distraction osteogenesis of the midface after surgery. CASE REPORT: We discuss the use of an extraoral distraction device after the osteotomy of a 10-year-old girl with Crouzon's disease. and the use of an internal device for a 6-year-old boy with severe midface hypoplasia following Apert's syndrome. RESULTS: In both patients a significant improvement of function, as well as harmonisation of the facial proportions, could be observed and the preoperatively planned distances of midface advancement of 18 and 15 mm respectively could be achieved. DISCUSSION: Distraction osteogenesis is an established procedure for the treatment of mandibular hypoplasia but few reports dealing with complex midface distraction are available outside of the specialist English language literature. We report on both external and internal distraction techniques with which good functional and aesthetic results were achieved.     

Vertical distraction osteogenesis of the alveolar process using a tooth-borne device]

Since the communication of McCarthy et al. in 1992, applications for distraction osteogenesis in the maxillofacial complex have increased enormously. The advantages as compared to conventional reconstructive procedures are missing donor-site morbidity for bone graft harvesting, reduced blood loss and also a gradual gain in the soft tissue envelope. Meanwhile, even the vertical lengthening of the alveolar process has become a clinically reliable method. The case presented illustrates the treatment of a 16-year-old patient who suffered a sporting accident at the age of 7 years, leading to ankylosis of the upper middle incisors with subsequent underdevelopment of the frontal alveolar process. After fabrication of a custom-made distraction device, an osteotomy of the tooth-bearing segment in the upper front was performed and the segment was attached to the distraction device. Bone lengthening was started on the seventh postoperative day at a daily rate of 0.5 mm. The distraction was maintained until closure of the open bite was achieved. On the 22nd day, the segment was fixed using an orthodontic arch wire and the distraction device was removed. A retention period of 6 weeks was maintained until sufficient stability was detectable. Now, 1.5 years after the treatment, the situation is stable with a good consolidation of the bone fragments and a physiologically shaped gingivobuccal sulcus. Lengthening of the alveolar process by vertical distraction osteogenesis using a tooth-borne device may be indicated in certain cases. With this technique a second operation can be avoided and there is less risk of laceration of dental roots by fixation screws.     

Maxillary sequels in labial-alveolar-velopalatine clefts. Orthodontic management

Routine othodontic management is unavoidable in all patients with cleft lip and palate after primary surgery. This management combines dental arch alignment with maxillary expansion of the lesser fragment before alveolar bone grafting. To treat dental arch asymmetry, the space of the missing lateral incisor is preserved until the age of dental implant. Otherwise, dento-orthopedic treatment attempts to normalize transversal dental dimension once alveolar bone grafting is done in order to prepare the surgical advancement of the maxilla.     

Predictability of maxillary distraction with the trans-sinusoidal distractor

INTRODUCTION: This work was conducted to evaluate a new maxillary distractor with an activating system introduced into the maxilary sinus. PATIENTS AND METHOD: Fourteen patients age 8 to 55 Years with severe maxillary and midfacial hypoplasia were treated in our center. A trans-sinusoidal maxillary distractor (TS-MD, developed by Dr. N. Nadjmi in cooperation with Martin, Tuttlingen, Germany) was placed intra-orally at each side of the maxilla. The distraction vector was predicted with devoted software (Medicim N.V Belgium), and was transferred to the patients using stereolithographic models and individual templates. A high Lefort I type osteotomy was performed. RESULTS: Forward maxillary movement at distractor level varied from 7 to 22 mm. Soft and hard tIssue formation resulted in complete healing across the distraction gaps. The maxillary movements and new bone formation in the sagittal, horizontal, and vertical planes could be predicted and achieved. Distractors were designed to allow clockwise rotation of the maxilla during the distraction phase allowing the correction of the anterior open-bite in all patients with this skeletal deformity. The distractors were almost completely submerged, and could be left in place as long as necessary to avoid relapse. DISCUSSION: The TS-MD distractor has the advantage of good tolerance since the most voluminous part is placed within the maxilary sinus. Implantation via an exclusively oral approach is a further advantage. The devise does not interfere with the patient's social life and does not require alveolodental fixation. The TS-MD distractor can also aleviate the need for bone grafting in cases with major advancement. Correct position of the vector is crucial but one-sided catch-up distraction is possible.     

The molecular biology of distraction osteogenesis

Distraction osteogenesis has become a mainstay in bone engineering and the recent application of this technique to the membranous craniofacial skeleton has significantly improved our armamentarium for reconstructive craniomaxillofacial procedures. However, if the biomechanical, histological and ultrastructural changes associated with distraction osteogenesis have been widely described, the molecular mechanisms governing the formation of new bone in the interfragmental gap of gradually distracted bone segments remain largely unclear. Recently, our laboratory has described a rat mandibular distraction model that provides an excellent environment for deciphering the molecular mechanisms that mediate distraction osteogenesis. In this Article, we present the hypotheses and current research that have furthered our knowledge of the molecular mechanisms that govern distraction osteogenesis. Recent studies have implicated a growing number of cytokines that are intimately involved in the regulation of bone synthesis and turnover. The gene regulation of numerous cytokines (Transforming Growth Factor-B, Bone Morphogenetic Proteins, Insulin-like Growth Factor-1, Fibroblast Growth Factor-2) during distraction osteogenesis have been best characterized and will be discussed in this text. We believe that novel systems like the rat model will facilitate our understanding of the biomolecular mechanisms that mediate membranous distraction osteogenesis and will ultimately guide the development of targeted-strategies designed to accelerate bone healing.     

Effect of recombinant human bone morphogenetic protein 7 on bone density during distraction osteogenesis of the rabbit mandible

OBJECTIVES: To examine whether the quality of bone generation in distraction osteogenesis of the rabbit mandible is enhanced by administering recombinant human bone morphogenetic protein 7 (rhBMP-7) to the lengthened site at the end of the distraction phase. STUDY DESIGN: Prospective randomized study of 24 rabbits undergoing distraction osteogenesis of the mandible, followed by injection of rhBMP-7 or a lactate buffer. SETTINGS: McGill University animal care facility. METHODS: Twenty-four white New Zealand rabbits underwent unilateral mandibular osteotomy and application of an Orthofix uniplanar M-100 fixator (Orthofix Inc., Verona, Italy) to the mandible. Mandibular distraction was carried out for 3 weeks. The animals were divided into three groups: group 1 (eight rabbits), control group: distraction, no injection; group 2 (eight rabbits), study group: distaction + injection of 200 microg of rhBMP7-lactate buffer; group 2 (eight rabbits), comparison group: distraction + injection of lactate buffer. All rabbits were sacrificed 7 weeks after surgery. The mandibles underwent radiology and bone densitometry analysis. MAIN OUTCOME MEASURES: Radiology assessment of bone generation within distracted segments and objective analysis of bone mineral density. RESULTS: Radiology confirmed the presence of bone generate within distraction sites. Densitometry showed a difference in bone mineral density among the three groups (p < .05). CONCLUSION: Local injection of a single dose of 200 microg of rhBMP-7 did enhance bone density when compared with the control group, although not in a statistically significant way when analyzed by an x-ray bone densitometer. This study serves as a starting point for future studies in bone tissue engineering by guiding the strategic administration of rhBMPs and the use of new state-of-the-art technologies, such as micro CT scanning, to analyze in a more detailed way, the effects of rhBMP administration.     

Maxillary distraction complications in cleft patients

INTRODUCTION: Cleft lip and palate (CLP) patients often present with a class III malocclusion in connection with a three dimensional maxillary hypoplasia. Twenty-five to 60% of these patients require a maxillary advancement. Two solutions are possible: orthognathic surgery and maxillary distraction. The purpose of this study was to evaluate the complications of the maxillary distraction in CLP patients. MATERIALS AND METHODS: Data was collected from the records of patients treated at our Surgery Unit between 2000 and 2007. Among the eight patients (four male and four female), five presented a bilateral CLP, two a unilateral CLP and one a unilateral cleft lip associated to a soft palate cleft. The average age at surgery was 17 years old. All had a Le Fort I osteotomy with a pterygomaxillary disjunction. The first two patients had external distractors and the six following internal ones. After a seven-day latency, activation was led to the rate of 1mm per day twice. The period of consolidation was four months on average. The maxillary advancement varied between 7 and 19mm with an average of 12.6mm. The average follow-up was four years. RESULTS: We encountered difficulties and/or complications in seven patients: one intraoperatively haemorrhage, one avulsion of a tooth fixed at the pterygoid process during the osteotomy, three device failures, two cases of significant pains during activation, one dissociation of the dental anchorage of an external system, two labial ulcerations and one maxillary sinusitis by migration of the 18. DISCUSSION: Difficulties of maxillary distraction in CLP patients are very frequent. The majority is related to the distractors and did not interfere with the final result. But this frequency must be taken into account in the indication and in the choice of the material. Two types of complications can occur during distraction: those related to the osteotomy and those related to the material. The complications related to the osteotomy are in connection with the cicatricial ground of the CLP. They are not specific of the distraction. We especially managed complications related to the material. The social benefit of the internal distractors is undeniable, but the design of certain models must be reexamined to improve their tolerance.     

Bidirectional and unidirectional distraction of defects of the alveolar process comparative clinical study]

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.     

Acquired Maxillary Sinus Hypoplasia: A Consequence of Endoscopic Sinus Surgery?

The effects of functional endoscopic sinus surgery (FESS) on sinus and midfacial development remain unclear. The authors report five children who, at a median age of 30 months, underwent FESS for refractory sinusitis. Three of the children had cystic fibrosis, and two had asthma. Preoperative computed tomographic (CT) scanning showed symmetric maxillary sinus development with varying degrees of mucosal disease. At a mean of 42 months after surgery, CT scans were obtained to evaluate recurrent symptoms in the five children. The scans showed unilateral maxillary hypoplasia in four children and bilateral maxillary sinus hypoplasia in one child. No child had clinically apparent facial asymmetry or midfacial hypoplasia. The authors also discuss the factors involved in maxillary sinus pneumatization, the possible effects of sinus surgery on sinus development, and the clinical implications of “acquired” maxillary sinus hypoplasia. Laryngoscope, 106:1210-1213, 1996     

Overview of the radiology,histology, and bone morphogenetic protein expression during distraction osteogenesis of the mandible

INTRODUCTION: Distraction osteogenesis (DO) is a form of in vivo tissue engineering during which an osteotomy and controlled distraction are used to lengthen bone. The molecular signals that govern distraction-induced bone formation have not been fully elucidated. Specifically, the role of bone morphogenetic proteins (BMPs) in DO of the mandible remains unclear. OBJECTIVE: To characterize the radiologic and histologic evolution of newly formed bone during DO of the mandible and to relate these changes to the expression of BMPs. METHODS: Fourteen skeletally mature male rabbits were used. A distractor device was surgically applied to one side of the mandible following osteotomy. After 1 week (latency period), distraction was started at a rate of 0.25 mm every 12 hours for 3 weeks (distraction period) and was followed by a 3-week consolidation period. Two animals were sacrificed each week after surgery (weeks 1 to 7). The mandible was resected and the new bone assessed by radiography and histology. The expression of BMPs was also analyzed using immunohistochemistry. RESULTS: There was radiographic and histologic evidence of bone formation during the distraction period. By week 6, there was mature woven bone within the distraction zone. Bone morphogenetic proteins 2 and 4 were strongly expressed in osteoblasts during distraction and in chondrocytes during consolidation. The expression of BMP-7 was relatively minor. CONCLUSION: The temporal and spatial pattern of BMP expression suggests that these proteins are important mediators of mandibular DO. Understanding the expression of BMPs may facilitate the use of recombinant proteins to enhance the rate and quality of bone generation during craniofacial DO.     

Changes in the nasal airway by transverse distraction of the maxilla]

OBJECTIVE: To investigate nasal airway changes through transverse maxillary distraction osteogenesis by means of an objective, reliable, noninvasive investigation technique with special attention to nasal valve changes and widening of the posterior maxilla. PATIENTS AND INTERVENTION: Eight patients with a severe maxillary transversal deficit underwent surgically assisted rapid palatal expansion in local or general anesthesia. Before and after the distraction process, a transnasal series of acoustic measurements of nasal airway profile was performed under topical decongestion. Nasal volume was calculated by integration of the area profile. The cross-sectional area of the nasal valve was also determined. RESULTS: A significant enlargement of nasal volume was recorded in all patients (P < 0.01: Wilcoxon signed rank test). The average increase measured 5 cm3 (23%). The increase in volume was recorded in all parts of the nasal cavity, indicating complete maxillary expansion even in the posterior segment. The nasal valve area raised from 0.56 to 0.70 cm2 (P < 0.01). Six out of eight patients reported striking improvement of nasal patency after maxillary distraction. CONCLUSION: Besides correction of the maxillary arch deformity, rapid palatal expansion contributes to improved nasal patency by resolving nasal valve constriction. Significant widening of the posterior nasal cavity was achieved, indicating a translational pattern of maxillary movement, although the pterygomaxillary junction was not touched in the osteotomy.     

Oronasal fistula in sequels of labialalveolarvelopalatine clefts

Labial and palatine maxillary clefts are treated by surgery, as for oronasal fistula. One of the most important parts of management is the timing of primary surgery in order to avoid growth disturbance. The authors describe the various possibilities to close secondary oronasal fistula. The timing and choice of surgical techniques are still debated and being improved. Various surgical techniques are available, from mucoperiosteal palatal flap to a free flap. Nevertheless, the mucoperiosteal palatal flap is the most commonly used. In some cases mucoperiosteal flaps are impossible to perform, so other options for extreme cases are discussed.     

Distraction osteogenesis. Applications for mandibular regrowth.

One experimental surgical technique of bone replacement demonstrates the greatest potential for clinical applicability in the near future: the regrowth of bone by distraction (stretching). Distraction osteogenesis defines the technique of growing new bone by stretching existing bones. Although this technique does not represent the ultimate method of mandibular reconstruction, it shows sufficient promise that its eventual use for specific types of mandibular defects probably will occur in the near future.     

Enophthalmos presenting as a silent sinus pathology

Without any signs of trauma or surgery medical history, the spontaneous enophthalmos could be secondary to maxillary sinus hypoplasia on the same side. The pathology which often lacks symptoms causes resorption and remodeling of the orbital floor. We present one case of maxillary sinus hypoplasia with enophthalmos and big ethmoidal bullae associated to septal deformity. Review of the bibliography in relation to the causes, medical history and treatment.