Animal experimental study on the role of the lateral pterygoid muscles in healing process of the sagittal fracture of mandibular condyles

Objective To examine whether they may further cause joint ankylosis lateral pterygoid muscles influence condyle morphology in healing process of sagittal fracture of mandibular condyles(SFMC).Methods Twelve healthy adult sheep were included in our study,and all animals were treated with surgery to make condyles fracture on right side of temporomandibular joint.The animals were randomly divided into two groups:the pterygoids of sheep in one group were cut and not able to function.The others in other group were not cut.They were still on internal poles of fractured condyles and their functions remained.We immediately examined whether pterygoid muscles were cut(or not) by MRI after operation.3D computed tomograms(CT) were taken 1,4,12 and 24 weeks after operation.Measure displacement of internal poles of fractured condyles,and changes in internal and external diameters of mandibular condyles.The sheep were put to death 4,12,and 24 weeks after operation.3D CT were taken then.After multiplanar reconstruction,measure related parameters about condyles so as to observe change of condyles.Results The CT scanning showed that changes in internal and external diameters of mandibular condyles were obviously different in two groups(P0.05),that internal poles of fractured condyles were distracted by pterygoid muscles and that influence on condyle morphology after sagittal fracture was more obvious in group where functions of lateral pterygoid were kept.Conclusions The building of this animal model proves that lateral pterygoid muscle does influence condyle morphology after sagittal fracture.This study provide research platform for study of the role of distraction osteogenesis of lateral pterygoid muscle in traumatic ankylosis of temporomandibular joint.