| Objective To explore the effect of vertical distance increase on the temporomandibular joint disc of osteoporotic rats by putting the occlusal pad on the posterior tooth area of osteoporotic rats,so as to provide some experimental support of open occlusal for orthodontic patientsMethod 1 90 SD rats,female,6 months old,body weight 210g?230g,randomly selected 40 rats as normal group,selected 45 rats among the remaining rats for intragastric administration of retinoic acid,5 rats for intragastric administration of distilled water with equal volume.After 15 days,5 rats were selected from the rats in the each gavage group for testing.The body weight,serum alkaline phosphatase(ALP)content,reproductive system organ coefficient,and femoral bone density(BMD)of the two groups were measured to establish an animal model of osteoporosis.2 The 40 rats that have been successfully modeled are divided into two groups,A and B,with 20 rats in each group.Group A is osteoporosis+pad group,and group B is osteoporosis group.A further 40 normal rats were selected and divided into two groups,C and D,with 20 rats in each group.Group C was the normal+pad group,and group D was the normal group.The vertical distance increase model was established on the bilateral maxillary molar region pads of rats in groups A and C,and no measures were taken in group B and D.Each group was sacrificed at various time points(1 week,2 weeks,3 weeks and 4 weeks).After tissue fixation,CBCT was used to observe the morphology and position of the condyle of the rat's temporomandibular joint and its position in the joint fossa;HE staining was used to observe the tissue structure and inflammation of the rat joint disc;immunohistochemical staining was used to detect the expression level of TNF-?,Image-Pro Plus 6.0 software was used to measure the positive expression optical density value(MOD value)of TNF-?.All data are statistically analyzed by SPSS 26.0 statistical software.Results 1 After 15 days of modelling,there was a statistically significant difference in body mass between the osteoporosis model group and the blank control group(P<0.05);the serum alkaline phosphatase(ALP)content was significantly different between the two groups(P<0.05);the difference in the organ coefficients of the reproductive system between the model group and the control group was statistically significant(P<0.05);for the results of the BMD of the femur in the rats,there was a significant difference between the two groups(P<0.05).2 CBCT observation results showed that in the first 3 weeks,the condyle of group A showed irregular shape,the joint space became smaller,and with time,the degree of irregularity of the condyle increased or even a slight bone defect,the joint space almost disappeared;The morphological structure of condyle in group C was normal,and the joint cavity decreased slightly.Over time,the morphological structure of condyle was slightly abnormal,and the space of joint cavity decreased slightly;at week 4,the condyle of group A was still irregular.No obvious bone defect was found,and the joint space increased slightly;the morphological structure of condyle in group C was normal,and the size of joint space was normal.HE staining showed that the inflammation of the articular disc of group A showed an upward trend at 1 week,2 weeks and 3 weeks,and the fiber damage gradually deepened.At 4 weeks,the inflammation was relieved but did not subside,and the fiber structure Partially restored.In group C,at 4 weeks,the inflammation of the temporomandibular joint disc almost disappeared,and the fiber structure was normal;immunohistochemical staining showed that at 1 week,2 weeks,3 weeks and 4 weeks,There is a statistical difference between the group A and the other three groups(P<0.05);and there is a statistical difference between the group B and D at each time point(P<0.05);Group C and D comparisons were statistically significant in the first 3 weeks(P<0.05),but there was no statistically significant difference at 4weeks(P>0.05).Conclusion 1 The increase of the vertical distance will cause certain pathological changes in the rat's temporomandibular joint disc.2 The pathological changes of the temporomandibular joint disc can be recovered easily after the vertical distance of normal rats increases.3 The pathological changes time of the temporomandibular joint after the vertical distance of osteoporotic rats was increased,and the pathological damage was not easy to recover.Figure 23;Table 8;Reference 89... |
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