ABSTRACT
BACKGROUND:Condylar fracture can occur under direct and indirect forces, and however, its risk and correlation with the impact site are rarely reported. OBJECTIVE:To quickly establish normal mandible three-dimensional finite element model and to analyze the strain conditions of the condyle under force at different parts of the mandible. METHODS: An adolescent volunteer was examined by multilayer spiral CT scans, whose mandible was normal and oral cavity was healthy. We used the reverse engineering software Mimics and large finite element software MSC.Patran to establish the three-dimensional finite element model of the mandible and to verify the feasibility of the model in the impact test at the body of the mandible, chin, mandibular angle and condyle. RESULTS AND CONCLUSION:A rapid establishment of mandible dimensional finite element biomechanical model could reproduce the morphology of the mandible, which was able to obtain the overal visual impression of the mandibular condyle. Geometric model included 80 044 nodes and 18 441 units. The mandibular chin, one side of the body, mandibular angle and condyle were given 100 N force respectively. The maximum equivalent stress of the bone cortex appeared in condylar region. So the mandibular condylar fractures were at the greatest risk. Experimental results contribute to mechanicaly analyze the condylar fracture type and to judge the severity of fractures.
ABSTRACT
Objective To introduce the newest type of mouth-gag for cleft palate palatorrhpy.Methods The instrument consisted of forcipal retractor,tongue-spatula,and spatula fixatiou screw post.Results Its structure was simple,light-weight and small.The operation was convenient and the fixation is firm.It gave a clear field of vision for surgery.Conclusion The new-type cleft palate palatorrhphy solves the problems in the old-type one.
ABSTRACT
Objective To explore and estimate a new non-operative treatment of maxillary fracture with elastic traction for the purpose of early treatment and on-spot first aid. Methods 12 patients, who were suffer from maxillary fracture including Lefort Ⅰ, Ⅱ, Ⅲ fracture, zygomatico-maxillary complex fracture and nasomaxillary complex fracture within the past 2 or 3 weeks,were treated by closed tractive reduction with a patent craniomaxillary tractive device, a non-operative manner instead of surgical open reduction and rigid internal fixation. The devices were placed after dental splints had been ligated, and the traction force was adjusted depending on the extent of maxillary displacement and patient’s endurance. In general, the displaced maxilla could be pulled upwards, downwards, forward, leftward and rightward. For fallen maxilla, a special plate was placed on upper teeth and palate in order to push up the whole maxillary fragments. By adjusting the position of maxillary bar, the displacement could be reduction and correction. The elastic rubber loops were placed between dental splint and headframe, then the reduction of maxilla was accomplished. After reduction, external fixation such as intermaxillary fixation and craniomnetal bandage were used for maintenance. Results Tractive times of those 12 patients lasted from 2 days to 7 days, with an average of 4 days. After the non-operative trative reduction, satisfactory functional and cosmetic results were achieved with normal occlusion and facial contour in all patients. No obvious complications were found. Conclusion For fresh maxillary fracture except comminuted and impacted fracture, this new non-operative tractive treatment could be an ideal treatment rather than surgical open reduction.