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.

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.

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.

?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

Objective: To establish an efficient animal model for the study of explosive injury in maxillofacial region.Methods: The detonator, steel spheres as fragments simulants shot by smooth-bore barrel and a synchronizer were used to define the wound model in the maxillofacial region of 18 dogs. The whole system was triggered when shooting. Wounding parameters and the changes of targets after explosion were observed and recorded. Results: The overpressure of blast wave decreased exponentially according to the distance from explosive. After injury, the local damage of dogs was serious and extensive compounded with the damages in heart, lung and brain. The injury was aggravated with the increasing of over pressure and energy absorption. Conclusion: The new wound model can be used for the study of explosive injury in maxillofacial region that is characterized by serious tissue damage and multi-etiology.

Objective :To study the effects of NO precursor, L-arginine(L-Arg) and constitutive nitric oxide synthase(cNOS) inhibitor, L-nitroarginine(L-NNA)) on the expression of cNOS in facial nerve and surrounding tissues in traumatic facial paralysis rats. Methods:Facial paralysis was surgicaly created by impact in 57 SD rats. The rats were divided into 3 groups with 18 in each group, another 3 rats were used for morphological study. L-Arg at 40 mg/kg or L-NNA at 50 mg/kg were intraperitoneally injected into rats 2 times a day, from 4 days before untill 14 days after surgery(group L-Arg and group L-NNA). In control group(NS) same volume of normal saline was given to the rats after creation of facial paralysis. The facial nerve and surrounding tissue samples were obtained at different time. Immunohistochemical ABC method was used to examine cNOS and inducible NOS (iNOS) expression in facial nerve and surrounding tissues. Results:cNOS immunoreactivity was observed in traumatic facial nerve in L-Arg group 7 days after trauma and in the adjacent muscle in the 3 groups from 6 h to 3 d after trauma. iNOS was found in the paralyzed nerves from 1 d to 7 d after trauma in the 3 groups, and in the adjacent tissues from 6 h to 3 d after trauma in the 3 groups. Conclusions:L-Arg may stimulate constitutive NOS expression in facial nerve and probably promote the nerve regeneration.

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.

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.