The Biomechanical Study Of RIF In Maxillofacial Fractures

The study is to establish a functional maxillofacial fracture biomechanical model, to provide the base of the study of RIF. To study the biomechanical behavior of RIF after simple mandibular fracture, complex mandibular fractures and Lefort I maxillary fracture. To compare the stability under different fixation method, and analyze the bite force under different fixation method.The polyurenthane synthetic mandibular replicas were used to simulate the mandible and maxilla. Different force of masseter medial pterygoid, temporalis and lateral pterygoid muscles were loaded on the replicas to simulated ICP, INC and MOL biting condition. By analyzing the stress on the plate, the displacement of the fracture gap and the bite force in different condition, we compared the stability of the different fixation methods. The data were gethered by DH5932 and DH3940 instrument. 5 models were measured in each group.We have succeeded in developed a functional RIF model of maxilla and mandibular fracture in ICP, INC and MOL conditions. Two mini-plates for treatment of mandibular angle fracture were stable. In mandibular symthesis, two miniplates were necessary to resist the power of the bend force. In complex mandibular fracture, model 1 is the most stable, model 2 ,model 5 and model 6 were more stable were more stable than model 4. In Lefort I maxillary fracture, three miniplates each side could provide enough bite force as much as non-fractured model, two plates each side were also stable and could restore 90% of bite force.In this study, the accurate functional maxilla-mandible model was developed, which is the fundation of the biomechanical. The stress patterns of the mandible were changed by the position of bite force, and the miniplates in mandibular symthesis were banded. In the complex mandibular fracture, chenching in fractured side would make less stability. In Lefort I maxilla fracture, although 2 plates each side in anterior and middle butter could get stability, 3 mini-plates each side is the best. A new method of biomechanical study on RIF in maxillo-mandible fractures is viable, the result of the study is the foundation of the treatment in clinic.