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.