Effects of exogenous nerve growth factor on the expression of BMP-9 and VEGF in the healing of rabbit mandible fracture with local nerve injury.

BACKGROUND: Mandibular fracture healing is a complex process involving nerves and growth factors. Nerve growth factor (NGF) not only facilitates the maintenance of sympathetic neurite growth but also stimulates other growth factors that can promote the essential osteogenesis and angiogenesis for fracture healing. Therefore, it is necessary to analyze the combined effects of NGF, bone morphogenic protein-9 (BMP-9), and vascular endothelial growth factor (VEGF) to accelerate the healing of mandible fractures. METHODS: The models of mandible fracture with local nerve injury established in 48 rabbits were randomly divided into nerve growth factor group (NGF group), gelatin sponge group (GS group), blank group, and intact group. The recovery of nerve reflex was assessed by observing the number of rabbits with lower lip responses to acupuncture. The fracture healing was observed with visual and CBCT, and then callus tissues from the mandibular fracture area were collected for hematoxylin and eosin (HE) staining observation, and the expression of BMP-9 and VEGF in callus at different stages was detected by quantitative real-time PCR (qRT-PCR). RESULTS: Needling reaction in the lower lip showed the number of animals with nerve reflex recovery was significantly higher in the NGF group than that in the GS and blank groups at the 2nd and 4th weeks after the operation. The combined results of macroscopic observation, CBCT examination, and histological analysis showed that a large number of osteoblasts and some vascular endothelial cells were found around the trabecular bone in the NGF group and the amount of callus formation and reconstruction was better than that in the GS group at the 2nd week after the operation. The qRT-PCR results indicated that the expression levels of BMP-9 and VEGF in the four groups reached the highest values at the 2nd week, while the expression levels of both in the NGF group were significantly higher than that in the GS group. CONCLUSION: The exogenous NGF could accelerate the healing of mandible fractures. This work will provide a new foundation and theoretical basis for clarifying the mechanism of fracture healing, thereby promoting fracture healing and reducing the disability rate of patients.

Integrity of Human Mandibular Angle After Block Graft Harvest from Mandibular Body.

PURPOSE: To examine human mandibular angle integrity alterations accompanying a mandibular body block graft harvest surgical procedure. MATERIALS AND METHODS: Hemimandibles from 24 human cadavers were resected and sorted into one of three groups by residual dental status. The height of each hemimandible body was obtained and recorded. Acrylic bone cement was utilized to mount the hemimandibles at the mandibular condyle. Using standard surgical instruments and techniques, cortical bone of the mandibular body buccal plate was resected from the right hemimandibles. Left hemimandibles were used as a control. Each hemimandible was secured in an Instron 5565 mechanical unit. With forces placed on and perpendicular to the occlusal plane, each hemimandible underwent sequential loading until osseous fracture occurred. Descriptive statistics between grouped data were compared and discussed in terms of mean, minimum, and maximum. The statistical relationship between the maximal load, gender, and mandibular body height were identified. RESULTS: Donor and control hemimandible maximal load mean values were 423.63 N and 957.90 N, respectively. A statistically significant difference was present between maximal loads of donor and control hemimandibles (P < .0001). Correlations of statistical significance were present between mandibular bone height and maximal load in the control hemimandibles (P = .009). Correlations of statistical significance were not found between mandibular bone height, displacement at maximal load, and maximal load in the grafted hemimandibles (P >.05). No statistically significant correlation between dental status and gender was found in the donor and control hemimandibles (P > .05). CONCLUSION: After subjected to a typical block graft harvest surgical procedure, the human mandible's integrity is significantly altered. Gender, dental status, and mandibular bone height do not correlate with maximal load,and thus integrity, of donor and control mandibles.

Periodontitis May Restrain the Mandibular Bone Healing via Disturbing Osteogenic and Osteoclastic Balance.

Periodontitis has been advocated as a systematic chronic low-grade infection burden. However, the relationship between periodontitis and bone defect healing has not been elucidated. One hundred and eight male Wister rats were randomly assigned into three groups: control (healthy) group, periodontitis group, and periodontitis plus human tumor necrosis factor receptorII:IgG Fc fusion protein (rhTNFR:Fc) group. The experimental periodontitis model was established by ligaturing with orthodontic wire and silk suture plus local administration of 20 µl of lipopolysaccharide (LPS). Mandibular bone defects in size of 4 × 2 × 1 mm were created for all the rats and rhTNFR:Fc subcutaneously injected at neck at a dose of 2.5 mg/kg every 3 days for the periodontitis plus rhTNFR:Fc group. The gene and protein expressions of bone-related markers in the healing tissue were monitored and new bone formation was histologically evaluated. Tartrate-resistant acid phosphatase (TRAP) staining was performed to determine the number of osteoclasts. The results showed that the mRNA and protein expressions of osteogenesis-related markers were significantly lower while nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) gene expression was significantly higher in the periodontitis group. The periodontitis group showed decreased new bone formation and increased number of osteoclasts when compared to the control group. However, there was no significant difference between the periodontitis plus rhTNFR:Fc group and the control group. These results demonstrated that periodontitis may restrain the mandibular bone healing via disturbing osteogenic and osteoclastic balance in which tumor necrosis factor-α (TNF-α) could act as a leverage.

Effect of interfragmentary gap on the mechanical behavior of mandibular angle fracture with three fixation designs: A finite element analysis.

BACKGROUND: The aim of this study was to simulate stress and strain distribution numerically on a normal mandible under physiological occlusal loadings. The results were compared with those of mandibles that had an angle fracture stabilized with different fixation designs under the same loadings. The amount of displacement at two interfragmentary gaps was also studied. MATERIALS AND METHODS: A three-dimensional (3D) virtual mandible was reconstructed with an angle fracture that had a fracture gap of either 0.1 or 1 mm. Three types of plate fixation designs were used: Type I, a miniplate was placed across the fracture line following the Champy technique; Type II, two miniplates were used; and Type III, a reconstruction plate was used on the inferior border of the mandible. Loads of 100 and 500 N were applied to the models. The maximum von Mises stress, strain, and displacement were computed using finite element analysis. The results from the control and experimental groups were analyzed and compared. RESULTS: The results demonstrated that high stresses and strains were distributed to the condylar and angular areas regardless of the loading position. The ratio of the plate/bone average stress ranged from 215% (Type II design) to 848% (Type I design) irrespective of the interfragmentary gap size. With a 1-mm fracture gap, the ratio of the plate/bone stress ranged from 204% (Type II design) to 1130% (Type I design). All strains were well below critical bone strain thresholds. Displacement on the cross-sectional mapping at fracture interface indicated that uneven movement occurred in x, y, and z directions. CONCLUSIONS: Interfragmentary gaps between 0.1 and 1 mm did not have a substantial effect on the average stress distribution to the fractured bony segments; however, they had a greater effect on the stress distribution to the plates and screws. Type II fixation was the best mechanical design under bite loads. Type I design was the least stable system and had the highest stress distribution and the largest displacement at the fracture site.

The enhancement of osteogenic capacity in a synthetic BMP-2 derived peptide coated mineralized collagen composite in the treatment of the mandibular defects.

The novel synthetic peptide P17-BMP-2 could promote cell attachment and enhance osteogenic capability. A composite, comprising nano-hydroxyapatite, collagen and poly(L-lactide) (nHAC/PLLA), was an efficient scaffold for carrier of P17-BMP-2. Our aim was to investigate whether nHAC/PLLA/P17-BMP-2 accelerates the osteogenesis as a reliable method for mandibular defect healing in this study. The repair capability was assessed by the gross observation, X-ray test and histological observation in four animal experiment groups at 2 week and 4 week after surgery: Group A (control), Group B (nHAC/PLLA treatment), Group C (nHAC/PLLA with 2 mg/g P17-BMP-2 treatment) and Group D (nHAC/PLLA with 10 mg/g P17-BMP-2 treatment). The Lane-Sandhu X-ray scores of the four groups were compared among four groups as well. The results showed that the composites containing the highest content of P17- BMP-2 performed best. Therefore, the nHAC/PLLA with P17-BMP-2 composite can accelerate the osteogenesis for mandibular defect healing and could be an ideal biological material as a bone graft material option for clinical applications.

Nuances and Pearls of the Free Fibula Osteoseptocutaneous Flap for Reconstruction of a High-Energy Ballistic Injury Mandible Defect.

UNLABELLED: A clinical case demonstrating the use of a free fibula osteoseptocutaneous flap for reconstruction of a high-energy ballistic mandible defect is detailed. The surgical videos highlight key nuances and pearls of flap design, harvest, dissection, and execution of microsurgical anastomosis. Attention is also given to preoperative surgical planning and postoperative care. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Dynamic simulation and finite element analysis of the human mandible injury protected by polyvinyl alcohol sponge.

There have been intensive efforts to find a suitable kinetic energy absorbing material for helmet and bulletproof vest design. Polyvinyl alcohol (PVA) sponge is currently in extensive use as scaffolding material for tissue engineering applications. PVA can also be employed instead of commonly use kinetic energy absorbing materials to increase the kinetic energy absorption capacity of current helmet and bulletproof vest materials owing to its excellent mechanical properties. In this study, a combined hexahedral finite element (FE) model is established to determine the potential protection ability of PVA sponge in controlling the level of injury for gunshot wounds to the human mandible. Digital computed tomography data for the human mandible are used to establish a three-dimensional FE model of the human mandible. The mechanism by which a gunshot injures the protected mandible by PVA sponge is dynamically simulated using the LS-DYNA code under two different shot angles. The stress distributions in different parts of the mandible and sponge after injury are also simulated. The modeling results regardless of shot angle reveal that the substantial amount of kinetic energy of the steel ball (67%) is absorbed by the PVA sponge and, consequently, injury severity of the mandible is significantly decreased. The highest energy loss (170 J) is observed for the impact at entry angle of 70°. The results suggest the application of the PVA sponge as an alternative reinforcement material in helmet and bulletproof vest design to absorb most of the impact energy and reduce the transmitted load.

Do erupted third molars weaken the mandibular angle after trauma to the chin region? A 3D finite element study.

It has been suggested that third molars increase mandibular fragility because they do not contribute to its strength. For ethical reasons, a human study design that would permit the elucidation of this interference is not possible. This study evaluated the impact of the presence of erupted third molars on the mandibular angle of resistance when submitted to trauma. A three-dimensional (3D) mandibular model was obtained through finite element methodology using computed tomography (CT) with the geometry and mechanical properties to reproduce a normal mandibular structure. Human mandibles with no, one or two erupted third molars were evaluated. Whenever the third molar was present there was a greater concentration of tensions around the cervical part of its alveolus. Approximated Von Mises equivalent stress of the third molar region was 107.035 MPa in the mandible with teeth and 64.6948 MPa in the mandible without teeth. In the condylar region it was 151.65 MPa when the third molar was present and 184.496 MPa when it was absent. The digital models created proved that the mandibular angle becomes more fragile in the presence of third molars. When they are absent the energy concentrates on the lateral e posterior aspect of the condylar neck.

[Morphological features of reparative osteogenesis of experimental mandibular hole defects with use of osteoplastic material "Hialuost"].

On 45 outbred crawls in a comparative aspect studied motion of reparated osteogenesis in an area holed defects of lower jaw. It is well-proven positive influence is on the processes of alteration bone-tissue regenerat with formation of mature organspetiality of bone tissue.

Intubación nasotraqueal con fibrobroncoscopio como única posibilidad en un paciente con anquilosis de la articulación temporomandibular / Nasotracheal intubation with fibrobronchoscopy as the only possibility in a patient with ankylosis of the temporomandibular joint

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Blast injuries to the human mandible: development of a finite element model and a preliminary finite element analysis.

OBJECTIVE: In an attempt to explore new tools for constructing a model of blast injuries to the human mandible, a finite element method was used. This model allowed us to perform dynamic simulations and analyse the injury processes and severity of trauma to the human mandible from an explosion striking at the middle mandibular angle. METHODS: A 3D finite element model of the human mandible was created using digitally visualised CT scanning data of the human mandible. It was used to dynamically simulate the complete injury process of a blast event to a human mandible (at the middle mandibular angle) under the injury conditions of a 600 mg TNT explosion. The model was also used to elucidate the subsequent mandibular damage and the dynamic distribution of several biomechanical indices (e.g., stress, and strain). The resulting data were subjected to a comparative analysis. RESULTS: Simulation was successfully conducted for injury events in which 600 mg of TNT exploded at 3 cm, 5 cm and 10 cm from the middle mandibular angle of a human mandible; specifically, the simulation included the dynamic injury processes and the distribution of stress and strain in various parts of the damaged mandible. A comparison of the simulation data revealed that different blast distances resulted in considerable variation in the severity and biological indices of the mandibular injury. CONCLUSION: The finite element model was able to dynamically simulate the blast-initiated trauma processes to a human mandible, which allowed for investigation of the severity of damage to the mandible under different injury conditions. This model and the simulation method are conducive for applications in basic studies and clinical investigations of blast-initiated injury mechanisms of bone tissues.

Development of a finite element model for blast injuries to the pig mandible and a preliminary biomechanical analysis.

BACKGROUND: Explosive damages to the maxillofacial bones exhibit complex dynamic response processes; the current traditional model and methods for blast wounds are unable to meet research needs. The finite element (FE) method has obvious advantages in complex biomechanical analysis. The objective of this study was to develop an FE model for blast injuries to the pig mandible and investigate the feasibility of using FE method as an ideal research tool for mandible blast wounds. METHODS: A hexahedral FE model of a pig mandible was established to simulate explosive damage in air by using MIMICS and ANSA software. Then, the FE model was imported into LS-DYNA for computation. Finally, the LS-POST was used for the analysis and the measurements. At the same time, an experimental study was performed by measuring biomechanical data (strains and accelerations) and wound patterns from fresh pig mandibles to validate our FE model and simulation result. RESULTS: The FE model and the dynamic processes of blast injuries to the pig mandible were developed and simulated successfully, and most of the biomechanical data and wound patterns displayed no significant differences with experimental results. Stress distribution in the mandible was relatively uniform; high-intensity strain was mainly concentrated in the mandibular angle and ramus, especially along the location of the fracture line. CONCLUSION: The FE model and method of this experiment will be helpful for investigations in the biomechanical mechanisms of mandibular blast injuries and the subsequent human maxillofacial blast injury simulation.

[Computer simulation of projectile injuries to pig mandibular angle].

OBJECTIVE: To investigate the feasibility of computer simulation in maxillofacial firearm injury. METHODS: The three-dimensional finite element models and simulations of 7.62 mm, 5.56 mm standard bullets projectile injuries to pig mandibular angle were established by using MIMICS, ANSA, LS-DYNA and LS-POST software. Based on the simulation results, the bullet hole diameters, energy loss values, energy loss rates, von Mises stress, effective strain, effective strain rate dynamic contours at different time points were used for biomechanical analysis. RESULTS: The damage processe of 7.62 mm, 5.56 mm standard bullets projectile injury to pig mandibular angle were simulated successfully. The injury rate of 7.62 mm standard bullet and injury severity of the mandible were higher than that of 5.56 mm standard bullet. CONCLUSIONS: Computer simulation can simulate maxillofacial firearm injuries effectively and may become an important method for oral and maxillofacial firearm injuries analysis.

In vivo study of human mandibular distraction osteogenesis. Part I: bone transport force determination.

Distraction Osteogenesis (DO) is a surgical technique used to reconstruct bone defects. The evolution of forces acting during DO is known to be strongly influencing the clinical issue of the treatment. The aim of this study was to determine experimentally the time-dependent forces imposed on bone regenerate by a distraction device in the case of a mandibular DO consecutive to a gunshot wound. To evaluate the bone transport forces, some fixing pins of the distraction device were equipped with strain gauges. Measurements were done during the first weeks of the treatment. An equilibrium analysis was achieved to determine the forces acting in bone regenerate from strains in the pins. Those quantities evolved during the records approximately from 5 N to 3-4 N and 2 N to 0-0.3 N for the tension and shear forces, respectively, depending on the record duration. For the longest record, the callus lengthening reached 0.17 mm during 75 minutes. This decrease of force and simultaneous callus extension can be attributed to the viscosity of regenerate and the elastic energy release of the device. Essential data were obtained concerning forces, extension and their evolution during mandibular DO. The low force level obtained was attributed to the absence of resistance of the soft tissues in the case of ballistic trauma restoration.

Displasia fibrosa da mandíbula / Fibrous dysplasia of mandible

A displasia fibrosa da mandíbula é uma patologia óssea benigna que representa cerca de 2% de todos os tumores ósseos. Relatamos o caso de uma paciente de 11 anos de idade, com queixa de dor em região mandibular esquerda há 1 semana, com história de abaulamento da mesma região há 3 meses. Após realização de exames de imagem, foi diagnosticado displasia fibrosa da mandíbula. O objetivo deste relato é revisar as principais características clínicas, radiológicas e possíveis tratamentos para o caso, dando a devida importância para o seguimento ambulatorial pós-tratamento

Fibrous dysplasia is a benign bone disease which represents about 2% of all bone tumors. Here we report the case of an 11-year-old who complained of pain at the left mandible area for a week, with history of arching in this area for 3 months. Imaging examinations led to the diagnosis of fibrous dysplasia of the mandible. The aim of this work is to review the main clinical and radiological characteristics and possible treatments for the case, giving due importance to ambulatory follow-up care

Wound ballistics of the pig mandibular angle: a preliminary finite element analysis and experimental study.

To study wound ballistics of the mandibular angle, a combined hexahedral-tetrahedral finite element (FE) model of the pig mandible was developed to simulate ballistic impact. An experimental study was carried out by measuring impact load parameters from 14 fresh pig mandibles that were shot at the mandibular angle by a standard 7.62 mm M43 bullet. FE analysis was executed through the LS-DYNA code under impact loads similar to those obtained from the experimental study. The resulting residual velocity, the transferred energy from the bullet to the mandible, and the surface area of the entrance wound had no statistical differences between the FE simulation and the experimental study. However, the mean surface area of the exit wounds in the experimental study was significantly larger than that in the simulation. According to the FE analysis, the stress concentrated zones were mainly located at the region of impact, condylar neck, coronoid process and mandibular body. The simulation results also indicated that trabecular bone had less stress concentration and a lower speed of stress propagation compared with cortical bone. The FE model is appropriate and conforms to the basic principles of wound ballistics. This modeling system will be helpful for further investigations of the biomechanical mechanisms of wound ballistics.

Repair of canine mandibular bone defects with bone marrow stromal cells and coral.

Tissue engineering has become a new approach for repairing bone defects. Previous studies indicated that coral scaffolds had been utilized with bone marrow stromal cells (BMSCs) in a variety of approaches for bony reconstruction. In these applications, the degradation rate of the material did not match the rate at which bone was regenerated. In this study, a previously established 30 mm long mandibular segmental defect was repaired with engineered bone using green fluorescent protein-labeled osteogenic BMSCs seeded on porous coral (n = 12). Defects treated with coral alone (n = 12) were used as an experimental control. In the BMSCs/coral group, new bone formation was observed from 4 weeks postoperation, and bony-union was achieved after 32 postoperative weeks. The residual coral volume of the BMSCs/coral grafts at 12 weeks (20-30%) was significantly higher than that at 32 weeks (10-15%, p < 0.05), which was detected by microcomputed tomography and histological examination. The engineered bone with BMSCs/coral achieved satisfactory biomechanical properties at 32 weeks postoperation, which was very close to that of the contralateral edentulous mandible. More importantly, immunostaining demonstrated that the implanted BMSCs differentiated into osteoblast-like cells. In contrast, minimal bone formation with almost solely fibrous connection was observed in the group treated with coral alone. Based on these results, we conclude that engineered bone from osteogenically induced BMSCs and biodegradable coral can successfully repair the critical-sized segmental mandibular defects in canines and the seeding cells could be used for bony restoration.

[Bone defects of ramus mandibulae healing in rabbits under bioengineering constructions from titanium and gold alloy with xenogenic mesenchymal stem cells].

Aim of the study was substantiation in experiments on rabbit ramus mandibulae of the method of mesenchymal stem cells (MSC) on the carrier from titanium and gold alloy for reparative osteogenesis enforcement. There was shown stimulating action of the MSC implantation in the bone wound upon reparative osteogenesis at the terms from 1 to 4 months. It was concluded that implants from titanium and gold alloy may be used as carrier for MSC for bone tissue reparative regeneration stimulation.

[Regeneration processes in bone defects after implantation of composite material of different density of polylactide origin filled with HAP (experimental-morphological study)].

In experimental-morphological study on 6 dogs the dynamics of regenerate formation in ulna and mandible defects after implantation in them composite material of different density (0.46-0.50 and 0.38-0.42 g/cm(3)) of polylactide (PL) origin filled with HAP was followed at the terms of 6 and 9 months. Histologic study and structural determinant distribution analysis in the content of regenerate showed that optimal results according to the bone defect substitution by bone regenerate criterion at 9th month of the experiment were received after composite material from PL and HAP with the density of 0.38-0.42 g/cm(3) implantation. Newly formed trabecular bone tissue was seen in the regenerate and as well as strong tendency for bone matrix maturation. It was confirmed by the appearance of lamellar structures in newly formed bone trabecules situated in peripheral zones of bone defect. In bone mandible defects the substitution process of the implants from PL with HAP by the bone tissue was much slower than in ulna defects.

A new hypothesis of mechanisms of traumatic ankylosis of temporomandibular joint.

Temporomandibular joint (TMJ) ankylosis is a disease that severely affects the human health. Although it is well known that trauma is the most common cause of TMJ ankylosis, the mechanisms by which the traumatic TMJ ankylosis develops are unclear. The existing hypothesis is not convincing in explaining the genesis of traumatic TMJ ankylosis. We make a hypothesis that the distraction osteogenesis (DO) of the lateral pterygoid muscle combining with the dislocated and damaged disc is an important factor in genesis of traumatic TMJ ankylosis. If this hypothesis is verified, it will be helpful for the prevention of traumatic TMJ ankylosis and change the principle of management of sagittal fracture of mandibular condyle (SFMC).