| Background and Purpose:Occlusal trauma,which is commonly observed in dental clinics,is due to abnormal bite,chewing functional disorder and the occlusal interference of iatrogenic causes.Occlusal trauma has various biological effects on the temporomandibular joint.In recent years,several studies have suggested that cadherin-11 may play an important role in the occurrence and development of normal temporomandibular joint and may be associated with the progression of temporomandibular joint disorders.The aim of this experiment was to investigate the histological and morphological changes and the expression changes of interleukin-6,tumor necrosis factor-a and cadherin-11 in the temporomandibular joint structure through the establishment of occlusal trauma rat model.And in some way,we attempt to elucidate the influence mechanism of occlusal trauma to the temporomandibular joint and cadherin-11 relevant role in this progress,in order to provide new targets and ideas to the further exploration of the temporomandibular joint disorders related pathophysiology,clinical diagnosis and treatment.Materials and Methods:In order to establish the occlusal trauma rat model,we bonded three-quarter cobalt-chromium metal crown on the first right mandibular molar,which is about 1.0 mm higher than occlusal plane.Forty-five eight-week-old male Wistar rats(weight of about 180-220g)were randomly divided into group ?(Experiment group ?,EG ?),group ?(Experiment group ?,EG ?)and Control group(Control group,CG).Experimental group ?,which was occlusal trauma group,was divided into 1w,2w and 4w group.And each group had 5 rats.Experimental group ?,which was the corresponding removal of occlusal trauma two-week group,was divided into lw+2w,2w+2w and 4w+2w group.And each group had 5 rats.Control group was divided into 1w,2w,3w,4w and 6w group.And each group had three rats.All the rats were put to execution at the observation point and the specimens were fixed,decalcified,embedded and sliced into 5.0 ?m median sagittal serial slices.The tissue slices were prepared for the hematoxylin-eosin staining and immunohistochemical staining,which was to observe the histological and morphological changes and the expression changes of interleukin-6,tumor necrosis factor-? and cadherin-11 in the temporomandibular joint structure.We calculated the average optical density value of interleukin-6,tumor necrosis factor-? and cadherin-11 by the ImagePro-Plus6.2 software.And we used the statistical software,Graphpad Prism.6.x.C,for the corresponding statistical analysis.Results:Part ? The establishment of occlusal trauma models of ratsThis experiment and our previous experiments have already validated that three-quarter cobalt-chromium metal crown was stable and reliable and was able to achieve the goal of establishing the occlusal trauma models of rats,which showed obvious pathological damages in the periodontal tissue.Part ? The histological and morphological observation of TMJ of rats with OTThe hematoxylin-eosin staining showed that:CG:no obvious histological abnormality was found.EG ? 1w group appeared obvious inflammation,which mainly showed phagocytic vesicle increase and articular cartilage cells swelling.The inflammation of EG ? 2w and 4w group relieved but cartilage pathological changes were found,such as cartilage cells cluster proliferation and myxoid matrix change.EG II showed no difference compared with the control groupPart ? The expression changes of IL-6?TNF-?and Cad-11 in TMJ of rats with OTThe immunohistochemical staining showed that:CG:IL-6,TNF-?and Cad-11 showed weakly positive expression and was mainly distributed in the condylar mast cell layer and the cells between the mast cell layer and proliferation cell layer.EG ? 1w group showed that IL-6,TNF-?and Cad-11 were evidently strong positive(P<0.05);EG ? 2w and 4w group showed that the positive expressions of IL-6,TNF-aand Cad-11 were reduced compared with 1 w group(P<0.05);EG ? 1 w+2w group showed that the expression of IL-6,TNF alpha and Cad-11 were higher than the control group(P<0.05),but in 2w+2w and 4w+2w group,IL-6,TNF-aand Cad-11 were weakly positive,which was no statistical significance compared with the corresponding control group(P>0.05).Conclusion:The three-quarter cobalt-chromium metal crown is stable and reliable,which is applicable to the study of occlusal trauma.Occlusal trauma stage can induce the inflammatory response and even pathological damages in the temporomandibular joint of rats.Cadherin-11,which may be in coordination with IL-6 and TNF-a,may contribute to the development and progress of the temporomandibular joint inflammation. |
PDF Full Text Request