ABSTRACT
Objective To investigate whether the abnormal stress could cause the ultrastructural change of the rats′condylar cartilage in vivo .Methods Fifty‐four SD male rats were randomly divided into condylar neck osteotomy operation(OO)group ,con‐dylar neck fracture operation(FO) group ,and control group ,with 12 rats in each group .Then the OO group rats ,FO group rats and control group rats were executed and sampled at 1st week ,3rd week and 5th week separately to observe the structure of condyle with light microscope(LM ) ,scanning electron microscope (SEM ) and transmission electron microscope (TEM ) .Results LM showed that the general condylar thickness of OO group and FO group were thinner than that of control group at 3rd and 5th week . SEM showed that the collagen and fibre were exposed in the OO group and FO group at 3rd week and 5th week ,the fibre was bro‐ken in the OO group at 5th week .TEM showed that the hypertrophic cell in OO group was more mature than those of FO group and control group at 3rd week .The arrange of fibre was disorder in OO group at 1st week ,the fibre was more disorder and there was even leak in OO group at 5th week .Conclusion The abnormal stress in vivo could result in the ultrastructural change of the rats′condyle ,and this change relates with the stess change degree and affects the growth and development of condyle .