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PubMed2006

Histomorphometrical analysis of new bone obtained by distraction osteogenesis and osteogenesis by periosteal distraction in rabbits.

The aim of this study was to compare histomorphometrically the new bone tissue obtained using two different distraction methods, and evaluate these two methods in terms of their advantages and disadvantages. In 36 New Zealand adult male rabbits, divided into two groups, a gradual distraction was performed using a device placed on the lateral surface of the mandibular corpus. In one group osteotomy was not performed and osteogenesis by periosteal distraction (OPD) only was used. In the other group, conventional distraction osteogenesis (DO) was performed. After a 7-day latent phase, the same distraction protocol was applied to both groups. Each group of rabbits was further divided into three sub-groups killed on the 15th, 30th and 60th days of the consolidation period, and histological analysis was performed. The mean extent of newly formed bone tissue was 14.4 mm2 in the OPD groups and 25.4 mm2 in the DO groups. When compared statistically, there were significant differences between all the DO and OPD sub-groups. The newly formed bone tissue obtained by OPD was rich in interstitial fatty tissue. These results indicate that bone tissue newly formed by OPD is not suitable for occlusal forces.

Adipose Tissue↗
PubMed2002

Osteogenesis distraction and platelet-rich plasma for bone restoration of the severely atrophic mandible: preliminary results.

PURPOSE: The purpose of this study was to evaluate a new method of restoring severe atrophic mandible using platelet-rich plasma (PRP) during distraction osteogenesis. MATERIALS AND METHODS: Since 1999, 2 men and 3 women with severe atrophy (Cawood and Howell classes V and VI) of a completely edentulous mandible have been treated with a novel distraction procedure. During the surgery, a mixture of autologous bone graft, harvested from the iliac crest, and an autologous platelet concentrate, obtained from platelet-rich plasma, filled the distraction gap. This mixture constituted an autologous bone-platelet gel that was used to create a useful bony scaffold for distraction regenerate. After a latency period of 15 days, a distraction run of 0.5 mm/d, and a 60-day period of consolidation, the distraction device was removed and implants were placed simultaneously. RESULTS: In all treated patients, planned distraction height was achieved with a considerable enhancement of bony regeneration, and in all cases it was possible to place implants at a planned time. CONCLUSIONS: The combination of these recent and innovative regenerative methods seems to be effective in restoring the severe atrophic mandible.

Alveolar Bone Loss↗
PubMed2006

Vector alignment in maxillary distraction osteogenesis.

Maxillary distraction osteogenesis is an alternative treatment of cleft patients with severe maxillary hypoplasia. The aim of this paper is to present the combined surgical/orthodontic treatment of a cleft lip and palate patient and to evaluate the maxillary distraction procedure and the distraction vector in high Le Fort I osteotomy.

Adult↗
PubMed2002

Morphofunctional and clinical study on mandibular alveolar distraction osteogenesis.

Alveolar Distraction Osteogenesis (ADO) is a process which forms new alveolar bone to correct alveolar deformities in ridge height and width. This work aims (a). to verify the predictability of the augmentation of height of atrophic alveolar ridges using an extra-alveolar distraction device and (b). to study the bone processes in order to optimize implanto-prosthetic rehabilitation. ADO was performed on 10 patients with ridge deformities to obtain the required ridge augmentation. Clinical and radiological (OPT and CT with densitometric assay) evaluations were carried out during the following 12 weeks, before implant insertion. Biopsies at 40, 60 and 88 days were studied after general, specific and histochemical staining of slides; microradiographs were analyzed to evaluate the Trabecular Bone Volume. Forty days after the end of distraction, soft callus indicated the start of ossification. Sixty days after the end of distraction, the soft callus was largely converted into a network of trabecular woven bone; osteogenic activity was high and TBV was about 50%. Eighty-eight days after the end of distraction, the amount of bone appeared reduced, with a more ordered structure; bone formation activity and TBV also diminished, whereas osteoclast erosion was active. The densitometric assay shows values increasing from the end of distraction, particularly after implant insertion. Histological results show a regression in bone deposition processes 88 days after the end of distraction culminating in a virtual steady-state after a certain time. The results suggest that early implant insertion may be desirable to avoid bone loss due to mechanical unloading.

Absorptiometry, Photon↗
PubMed1997

Reconstruction of the mandibular condyle using transport distraction osteogenesis.

Transport distraction osteogenesis was used to reconstruct the articulation of the temporomandibular joint in two patients. Patient 1 underwent a gap arthroplasty for release of a bony ankylosis. Patient 2 had degenerative joint disease after tumor resection. Both patients had painful, limited mouth opening and facial asymmetry as a result of condylar shortening. A reverse-L osteotomy was performed from the sigmoid notch to the posterior border of the mandible. An external transport distraction device was applied, and the segment was advanced superiorly, 1.0 mm per day, until contact was made with the glenoid fossa. After distraction, the bone was found to have remodeled, inducing a new cortical layer on the articular surface. Additionally, a pseudodisk was generated as a result of the transport distraction. The two patients tolerated the procedure well, returning to pain-free normal mouth opening and being able to masticate regular diets.

Adult↗
PubMed2005

Strain-dependent control of transforming growth factor-beta function in osteoblasts in an in vitro model: biochemical events associated with distraction osteogenesis.

BACKGROUND: Distraction osteogenesis is an important clinical method for increasing bone mass, but its effects on bone-forming cells are not well understood. In this study, the authors asked how the mechanical forces that occur during this procedure alter specific osteoblast activities such as matrix synthesis, the rate of cell replication, and enzyme activities. The authors further asked whether these changes relate to differences in the biochemical response of osteoblasts to transforming growth factor-beta (TGF-beta), a potent regulator of bone formation. METHODS: Osteoblasts were plated on flexible, collagen-coated membranes. One group was unstrained, a second group experienced a single maximum strain load once every 6 hours to simulate intermittent force associated with a distraction protocol of four screw turns per day, and a third group was strained continuously for 24 hours. In the third group, some cell cultures were allowed to recover from strain before analysis. Subsequently, each group was treated with vehicle or TGF-beta at 12 pM (0.3 ng/ml) or 120 pM (3 ng/ml). Data were collected from a minimum of 15 replicate cell culture wells obtained from at least three separate primary culture preparations. Results were assessed with statistical software. Differences were considered significant with values of p < 0.05. RESULTS: Both strain protocols increased basal osteoblast DNA synthesis but suppressed the relative stimulatory effect of TGF-beta on this event. However, neither intermittent nor continuous strain significantly altered collagen or noncollagen protein synthesis or the relative effect of TGF-beta on these processes in osteoblasts. Basal alkaline phosphatase activity, an intermediate marker of osteoblast differentiation and an early marker of matrix mineralization, decreased significantly in response to continuous strain or to TGF-beta treatment, and even more so in response to both conditions. In addition, TGF-beta binding to the type III TGF-beta receptor was increased in proportion to strain intensity. CONCLUSIONS: This study shows that cyclic strain can alter osteoblast activity in multiple ways and predicts that TGF-beta has different effects during the distraction process on osteoblasts and therefore on their ability to effect bone formation. They further indicate that mechanical load permits early aspects of osteoblast activation but delays in part later biochemical parameters associated with mineralization to allow new bone growth before consolidation.

Animals↗
PubMed2006

Pediatric feeding disorder and growth decline following mandibular distraction osteogenesis.

BACKGROUND: Mandibular distraction osteogenesis has proven to be an effective treatment for upper airway obstruction related to micrognathia. Changes in the aerodigestive space can help facilitate tracheostomy removal in children and prevent tracheostomy in newborns. However, this may also precipitate changes in the ability to orally feed. There are few data on early postoperative feeding and growth rate following mandibular lengthening. The authors found evidence of growth rate decline and feeding difficulty in pediatric patients following mandibular distraction osteogenesis. METHODS: Ten pediatric patients underwent mandibular distraction osteogenesis for treatment of upper airway obstruction. Outcomes in resolution of upper airway obstruction, oral feeding success, and growth rate were analyzed. Follow-up ranged from 12 to 28 months. RESULTS: All 10 patients had complete resolution of upper airway obstruction. The length of distraction ranged from 10 to 17 mm. Three patients demonstrated a feeding disorder after mandibular distraction osteogenesis, defined as requiring a long-term (>1 month) alternate feeding method (gastric tube in two patients and gastric gavage in one). Seven of 10 patients exhibited an early decline in growth rate following distraction. Data used to determine growth rate changes were weight measurements at the time of distraction, at the time of distractor removal (6 to 8 weeks after distraction), and at 6 and 12 months after the date of distraction initiation. CONCLUSION: These results suggest that infants and children undergoing mandibular lengthening by distraction osteogenesis should be carefully monitored for postdistraction feeding disorder and growth rate disturbance.

Airway Obstruction↗
PubMed2004

Intermittent parathyroid hormone (1-34) enhances mechanical strength and density of new bone after distraction osteogenesis in rats.

Distraction osteogenesis is used both for leg lengthening and for bone transportation in the treatment of fractures and nonunions. The main problem with this method is that the time until full recovery may be up to a year, partly because of the time needed for the new formed bone to consolidate and become strong enough for weight bearing. We have studied whether intermittent parathyroid hormone (PTH(1-34)) could accelerate the consolidation of new formed bone after distraction osteogenesis in rats. Forty-seven, 3-months-old male Sprague-Dawley rats underwent lengthening of the right femur using an external fixator. After a middiaphyseal osteotomy and a 7-day latency period, the callus was distracted during 10 days, with a distraction rate of 0.25 mm twice a day. The consolidation time was either 20 days or 40 days after distraction was completed. A dose of 60 microg of human PTH(1-34)/kg body weight/injection or vehicle was given every second day beginning 30 days before the rats were killed. Both femura of each rat were subjected to mechanical testing and dual-energy X-ray absorptiometry. Blinded histological examination was done for the distracted femura. In the 20 days consolidation experiment, PTH(1-34) increased ultimate load (56%), stiffness (117%), total regenerate callus volume (58%), callus BMC (24%) and histologic bone density (35%) compared to untreated distraction osteogenesis specimens. In the 40 days consolidation experiment, PTH(1-34) increased ultimate load (54%), stiffness (55%), callus BMC (33%) and histologic bone density (23%) compared to untreated distraction osteogenesis specimens. Total regenerate callus volume was unchanged. The contralateral femur also became stronger, stiffer and denser under PTH(1-34) treatment, but to a lesser degree. PTH(1-34) might become useful to shorten the consolidation time after distraction osteogenesis in humans.

Animals↗
PubMed1997

Assessment of cell proliferation in regenerating bone during distraction osteogenesis at different distraction rates.

An experimental model of lengthening of the lower limb was used to study the morphology and cellular proliferation of regenerating bone tissue after 20% lengthening at four rates of distraction. Groups of rabbits were killed at different times 1-8 weeks after surgery. The regenerated area was divided into three zones: fibrous, primary mineralization front, and new bone. As the rate of distraction increased, the size of the fibrous zone increased and that of the new bone zone decreased. Necrosis, formation of cysts, and cartilage were found in the regenerated area at the higher distraction rates. Cell proliferation was assessed by in vivo labelling with bromodeoxyuridine, and the positive staining index for anti-bromodeoxyuridine antibody was calculated in the zones of the regenerated tissue. The index values for the fibrous zones and the new bone zones did not differ significantly in any of the groups. The value increased significantly (p < 0.05) in the primary mineralization front as the rate of distraction increased from 0.3 to 0.7 mm/day, but there was no further significant increase at higher distraction rates. In conclusion, cell proliferation was increased at all of the higher rates (more than 0.3 mm/day) of distraction studied. Higher rates of distraction caused tissue damage. A distraction rate of 0.7 mm/day appeared optimal for cell proliferation and histological characteristics.

Animals↗
PubMed2000

[Management of severe maxillary deficiency through distraction osteogenesis with external distraction device].

OBJECTIVE: To demonstrate a practical method for advancement of the midface using Le Fort I osteotomy and gradual distraction technique. METHODS: With the use of an external adjustable, rigid distraction device, we treated 6 patients with severe maxillary hypoplasia. Ages ranged from 11 to 15 years. They all underwent modified Le Fort I osteotomies assisted by gradual distraction. Four days postoperatively, distraction began at the rate of 1 mm/day for about 2 weeks. 4 weeks with the fixed distraction appliance and 6 weeks with a removable night-time face-mask retention, we then analyzed all those preoperative and postoperative protocols. RESULTS: Predictable results were obtained. Midface advancement ranged from 8 to 13 mm. A satisfactory class I or II molar relationship is achieved. The aesthetic results are excellent. Up to now, no relapses have been observed. CONCLUSIONS: This method of modified Le Fort I midface advancement has been shown to be clinically practical and effective.

Adolescent↗
PubMed1998

Mandibular distraction osteogenesis: a comparison of distraction rates in the rabbit model.

The rabbit model has been used to study the effects of different rates of distraction upon mandibular bone. Bilateral distraction was performed at two different rates anterior to the molar teeth. Both experimental groups were significantly inferior to sham operated controls in terms of bone density (DEXA) and mechanical testing. No difference in new bone formation between the two distraction rates was detected by these modalities. However, histological examination revealed non-union to be more common in the rapidly distracted group. This suggests that attempts to shorten the duration of external fixation in clinical mandibular distraction osteogenesis should be by methods other than more rapid distraction.

Absorptiometry, Photon↗
PubMed1999

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.

Adolescent↗
PubMed2006

Soft tissue to hard tissue advancement ratios for mandibular elongation using distraction osteogenesis in children.

Distraction osteogenesis is extensively used for the elongation of hypoplastic mandibles in children, yet the soft tissue profile response to this is not well understood. The pre- and posttreatment lateral cephalometric radiographs of 27 pediatric patients who underwent bilateral mandibular elongation using distraction osteogenesis were analyzed retrospectively to correlate horizontal soft tissue advancement with horizontal underlying bone advancement at B point and pogonion. Horizontal advancement (in millimeters) of bone and overlying soft tissue at these points was collected from the radiographs of each patient, and linear regression analysis was performed to determine the relationship of hard to soft tissue horizontal advancement at these points. A 1:0.90 mean ratio of bone to soft tissue advancement was observed at B point/labiomental sulcus and at pogonion/soft tissue pogonion (linear regression analysis demonstrated slopes [beta1 values] of 0.94 and 0.92, respectively). These ratios were consistent throughout the sample population and are highly predictive of the soft tissue response that can be anticipated. Magnitude of advancement, age, and sex of the patient had no effect on these ratios in our population. This study assists with our understanding of the soft tissue response that accompanies bony elongation during distraction osteogenesis which will allow us to more effectively treatment plan the orthodontic and surgical intervention that will optimize the patients' functional and esthetic outcome.

Adolescent↗
PubMed2003

Focal adhesion kinase expression during mandibular distraction osteogenesis: evidence for mechanotransduction.

Distraction osteogenesis is an established treatment strategy in the reconstruction of the craniofacial skeleton. The underlying mechanisms that drive bone formation during this process are largely unknown, but a regulatory role for mechanical force is believed to be critical. The integrin-mediated signal transduction cascade is a primary pathway by which signal transduction of mechanical stimuli (i.e., mechanotransduction) occurs. Focal adhesion kinase (FAK) is a significant regulator in this pathway. The authors hypothesize that mechanical forces created during distraction osteogenesis are responsible for the osteogenic response that takes place, and that these changes arise through integrin-dependent mechanotransduction. Using a rat model of distraction osteogenesis, the authors examined the expression of FAK in critical size defects (n = 15), subcritical size defects (n = 15), and mandibles undergoing distraction osteogenesis (n = 15). Their findings demonstrated FAK immunolocalization in mandibles undergoing distraction osteogenesis, but not in the critical size defects or in subcritical size defects, despite varying degrees of bone formation in the latter two groups. Furthermore, bone sialoprotein mRNA in situ hybridization patterns were found to mirror FAK immunolocalization patterns in mandibles undergoing distraction osteogenesis, demonstrating an association of FAK expression with the osteogenic process specific to distraction osteogenesis. These findings suggest that the bone formation in distraction osteogenesis is regulated by mechanical force by means of integrin-dependent mechanotransduction pathways.

Animals↗
PubMed1998

Applications of distraction osteogenesis. Part II.

Distraction osteogenesis is helpful for digit lengthening for congenital and post-traumatic deficits. Distraction lengthening is also helpful for soft tissue stretching such as for radial dysplasia. This article reviews some of these uses for distraction osteogenesis.

Child↗
PubMed2001

Closure of an oronasal fistula in an irradiated palate by tissue and bone distraction osteogenesis.

Uses for distraction osteogenesis in the craniofacial skeleton have expanded during the last decade. It has become an important rung in the reconstructive ladder for correction of difficult defects. Distraction of irradiated bone has been successfully performed in an animal model but has not been reported in human subjects. We present a case of distraction osteogenesis in a patient with multiple failed reconstructive attempts to close an irradiated palatal defect. An additional benefit included improvement in support of the upper lip from bone transported and the potential for placing dental implants.

Cranial Irradiation↗
PubMed2004

The role of bone morphogenetic proteins BMP-2 and BMP-4 and their related postreceptor signaling system (Smads) in distraction osteogenesis of the mandible.

Distraction osteogenesis has become a widely used clinical approach in the treatment of craniofacial and orthopedic disorders. The exact biological mechanism of bone formation remains illusive, however. The aim of this study was to evaluate the role of bone morphogenetic protein-2, bone morphogenetic protein-4, and transforming growth factor-beta superfamily-related postreceptor signaling glycoproteins Smads 1 through 5 in distraction osteogenesis. Twelve sheep randomly divided into two groups were distracted to 24 mm at 1 or 4 mm/d using a submandibular osteotomy and an external distractor. After a 5-week fixation period, the mandibles were harvested. Employing immunohistochemical techniques, the sections were investigated for the previous antigens. Osteoblasts and periosteal lining cells were strongly positive. The matrix did not stain for the antigens investigated. Osteocytes demonstrated weak staining for the antigens. No significant difference between the groups was noted. In fracture healing, bone morphogenetic proteins 2 and 4 have been localized to the cambial layer of the periosteum, where healing occurs by intramembranous ossification. Their diffuse staining of the osteoblasts in the distracted region supports a similar role in distraction osteogenesis, where bone formation is predominantly through intramembranous ossification. Furthermore, bone morphogenetic proteins 2 and 4 have been demonstrated to promote mesenchymal cell conversion to osteoblasts. This is similar to the process observed in distraction osteogenesis. The presence of related Smads confirms postreceptor activity of these bone morphogenetic proteins in the process of distraction osteogenesis. This study supports induction of bone morphogenetic proteins 2 and 4, their related postreceptor signaling system (Smads), and intramembranous bone formation associated with mechanical strain in distraction osteogenesis.

Animals↗