Objective: To view the characteristics and the primary treatment of civilian firearm wound in the maxillofacial region.Methods: 301 cases of the casualties admitted to our hospital were retrospectively investigated,the epidemic, etiology, wound characteristics, and treatments of the patients were viewed respectively. Results: Of all the cases, the ratio of male to female was 5.1∶1.0. 57% of the injuries were caused by gunshot, 66% were with multiple injuries.16% combination wound were craniocerebral injuries. In this group of patients, more than 900 wound tracks were found, 72% of the tracks were nonpenetrating and 67% of those were with foreign bodies lodged in. Burns with blast injuries were the main complex wounds, which mostly occurred in explosion. The treatments mainly included life maintaining, earlier debridement and infection control. Conclusions: The maxillofacial firearm injuries are complex and have their own characteristics depending on the firearms, the wound styles and the regional anatomy. All the factors must be considered when treatment is given.

Objective: To observe effects of treatment of mandibular fractures with compression or non compression internal fixation. Methods: In the in vivo study mandibular fractures were fixed by compression internal fixation on one side and non compression on other side in 15 dogs and observed radiologically and histologically. In clinical practice 42 patients with 58 mandibular fractures were treated with compression internal fixation, and 56 patients with 78 madibular fractures were treated with non compression internal fixation. Their clinical effects were evaluated by masticatory efficiency test, radiological and clinical observation after operation. Results: Primary bone healing was found histologically in group of compression fixation and bone healing through callus in group of non compression in the dogs. In the patients treated with compression internal fixation bone fracture line disappeared 1 week earlier and masticatory efficiency was heigher than in those with non comprission fixation. Conclusion: Both methods are all effective in the treatment of mandibular fractures. The miniplate is convenient in use and the indication is wide ranging. The compression plate can speed healing of mandibular fractures, but the operation is more strict technically.

Objectives: To study the prolonging of mandible by distr ac tion osteogenesis (DO) after severe trauma in rabbits. Methods:O steotomy was conducted in 16 adult rabbits. To simulate severe trauma,periosteum was removed and inferior alveolar vessels were destroyed on left side. The rabb its were randomly divided into 4 groups with 4 in each group and internal distra ctor was applied in each rabbit. In group A1 and A2 the latency time was 1 day,i n group B1 and B2 that was 7 days.In group A1 and B1 the distraction velocity wa s 0.5 mm/d,in group A2 and B2 that was 1.0 mm/d.The distraction length was 10 mm and retention period was 4 weeks. Results:4 weeks after operati on on right side complete new bone formation was found in the distraction area. On left side that was observed in group B1 and B2,but not in A1 and A2.Nonunion was found in 1,4,0 and 0 cases in group A1,A2,B1 and B2 respectively.The bending strength (10 4 N/m 2) of normal bone was 95,that in group A1,B1,B2 was 25,85 and 60 respectively. Conclusion:DO method can be used even after the blood supply of the mandibles has been destroyed, but the latency period sh ould be longer.

The injurious changes of the microvasculature in the maxillofacial region due to high-velocity bullet injury were observed in different time intervals with scanning and transmission electron microscopy. It was found that there were microthrombus formation in the vascular lumen, and endothelial loss and dege-neration or necrosis of the vascular wall in the microvasulature around the wound. Our findings indicate that when early reconstructive surgery for the tissue defect due to gunshot wound especially for those in the maxillofacial region is to be performed with microsurgical technique, it is essential for the surgeon to realize and consider the wounding condition on the microvasculature of the recipient site.

To investigate the temporal variation of cell mediated immunity in injured tissue of maxillofacial firearm trauma. Cells expressing messenger RNA(mRNA) for IL 2 were demonstrated by dot blotting and in situ hybrization in injured tissue of maxillofacial trauma inflicted by bullet, in conjunction with immunohistochemistry for IL 2 in normal and postinjury conditions. It was found that, apart from a transient eleratim in level within 24h post injury, both IL 2 production and IL 2 mRNA expression were consistently suppressed in cells at the site of the wound compared with the normal. The changes in the tissues of indirect injury by the projectile were significant. These results indicate that the cell-mediated immunity was suppressed in maxillofacial firearm trauma and the principal cellular abnormalities that resulted in altered T cell activation and IL 2 production postinjury was downregulation of mRNA before IL 2 gene transcription. It also suggested that the indirect injury by projectile contribute mainly to the depression of cell mediated immunity.

To observe the injury process and pathological changes of the facial nerve,a primer was detonated at a distance of 10 cm from the face of each of 36 anesthelized dogs to simulate blast injury of the maxillofacial region. At the same time, a tangential wound of masseter was produced by a steel pellet fired with a musket to simulate a shrapnel injury. At different time points after injury, the action potential of the facial nerves was checke d and the pathological changes in axons and neurons of facial nerves were observed after HE and Nissle′s staining,respectively.One day after the injury,the facial nerve axons were found to be disrupted extensively,although the epineurium was still in continuity. There were degeneration and necrosis of neurons with infiltration of inflammatory cells in the facial nerve.One week later, the inflammation began to become milder, and the necrotic neurons were gradually absorbed. Four weeks later, the survived neurons appeared normal, and axons began to regenerate. Meanwhile, electromyography (EMG) showed that the action potential of facial nerve recovered. All the observations suggested that severe indirect injury to the facial nerve trunks in an explosive injury was the main pathological changes which involved an extensive area with severe damage in neurons.

To investigate the temporal variation of cell-mediated immunity in injured tissue of maxillofacial firearm trauma. Cells expressing messenger RNA(mRNA) for IL-2 were demonstrated by dot blotting and in situ hybrization in injured tissue of maxillofacial trauma inflicted by bullet, in conjunction with immunohistochemistry for IL-2 in normal and postinjury conditions. It was found that, apart from a transient eleratim in level within 24h post injury, both IL-2 production and IL-2 mRNA expression were consistently suppressed in cells at the site of the wound compared with the normal. The changes in the tissues of indirect injury by the projectile were significant. These results indicate that the cell-mediated immunity was suppressed in maxillofacial firearm trauma and the principal cellular abnormalities that resulted in altered T cell activation and IL-2 production postinjury was downregulation of mRNA before IL-2 gene transcription. It also suggested that the indirect injury by projectile contribute mainly to the depression of cell-mediated immunity.

Objective:To study the biomechanical characters of human mandible under compression load and to deduce the constitutive equation.Methods: Specimens taken from five mandible of fresh human cadavers were examined on INSTRON by a group of tensile tests at different strain rates (0.000　5,0.005,0.05 and 0.5 s-1).Bone mineral density of every individual mandible was measured.The effects of strain rate(**),bone mineral density (ρ) on Young'Modulus (E),strength(σu)and ultimate strain(εu) were studied and the constitutive equations were deduced using the following model:Y=aρb**c.Results:(1)σu=216.27ρ1.23**0.055（P<0.01），(2)E(Pa)=5　604.024**0.083（P<0.01）,(3)εu =0.045**-0.045（P<0.01）,(4)σu=1　798.87ρ-1.17**0.083ε0.82（P<0.01).Conclusions:Strain rate and bone mineral density are important factors for the biomechanical characters of human mandible under compression load.Based on the constitutive equations,the stress level,the possibility and degree of mandible injury may be estimated.

?Objective: To study the effect of glial cell line derived neurotrophic factor (GDNF) on facial nerve regeneration after injury.Methods:Defect of 5 mm was made in each facial nerve on both sides in 32 rabbits.Silicon tubes were used to bridge the defects.Pure GDNF (15 ?g in 30 ?l silane) was injected into silicon tube on one side and saline (30 ?l) on the other side as the control.Nerve regeneration was studied by morphological observation with HE and Bielschowsky stainning,counting of nerve neurons and axon and measuring of motor nerve conduction velocity.The rest 3 rabbits was as blank contol. Results:7 d and 17 d after operation ,the neuron number in GDNF treated and control groups were 39.2?2.3 and 28.4?1.9,and 33.6?2.1 and 27.1?1.4,respectively ( P

objective: To investigate the effect of recombinant human basic fibroblast growth factor (rhbFGF) on cell proliferation during mandible fracture healing. Methods 8 ?g of rhbFGF in 0.3 ml of H 2O was mixed with 1.6 ml of bovine type 1 collagen and then the mixture was vacuumed to be a membrane. The membrane was implanted around the mandibular fracture following the fracture was made in 25 rabbits. 5 animals were sacrificed 1,2,4,8 and 12 weeks respectively after operation. Proliferating cell nuclear antigen (PCNA) in callus was examined with immunohistochemical staining. Type 1 collagen membrane was used as the control in another 25 rabbits. Results:1 week after operation, PCNA positive cell(%) in callus in rhbFGF treated and control group were 65.2?6.1 and 32.0?5.5 respectively ( P