Analysis On The Effects Of Resorption On Rats' Condylar By Low Level Estrogen

Objective:Idiopathic condylar resorption,also called condyle absorption which is a progressive pathological condylar defect for clinical manifestations of the disease.The symptoms of patients give rise to the opening and closing of the anterior teeth,mandibular clockwise rotation,class II malocclusion deformity and the vertical height decreased.There is still no specific explanation about the reason of ICR.The clinical study found that ICR usually occurred in 15 to 35 years old woman,and a big part of these women had contraceptive history and premature ovarian failure.The condyle is the target organ of 17 beta-estradiol(E2),which is secreted by adolescent females,so the relationship between estrogen and ICR is getting a lot of attention.This experiment explores the method to reduce the adolescent estrogen level of female rats by drugs and estabilished ICR model and to observa morphological and pathological changs in different stages at the same time.Finally,this essay discusses the pathologic mechanism of estradiol hormone in the process of condyle resorption.Method:5 weeks old healthy SPF virgin female SD rats at room.The temperature is 20 to25 degrees Celsius,relative humidity is 50%~60%,flow rate is less than 0.2,the ammonia concentration is less than 14mg/m3,the noise is less than or equal to 60 d B.Feed the rats a week under the environment of changing bedding.Make rats be familiar with the environment during feeding period..To detect estrous cycly during the feeding period and select 45 SD rats with nomal estrus cycle randomly divided into three groups.Group A Gavage pill group: according to the calculation of pill weight of rats(Ma Fulong)dosage: 0.0189mg/kg,Ma Fulong(Desogestrel and Ethinylestradiol Tablets)diluted in Sodium Chloride Injection made of crushed suspension by gavage once a day,1ml once,in order to reduce the serum estrogen level of female rats during puberty.Group B Premature ovarian failure group: according to the weight of rats to calculate the dose of cisplatin: 6.0mg/kg,cisplatin diluted in Sodium Chloride Injection,intraperitoneal injection,once a week,once a 1ml,a total of 2 weeks,prompting premature ovarian failure in rats.Group C Blank control group,fed with normal diet without any treatment.1.Before and after the experiment,the serum estradiol levels were measured by the blood of the eyes of the rats at fourth weeks and at the end of the eighth week and the twelfth week.2.The condyle was made into slices.After routine HE staining,the condylar bone parameters of rats were detected by imgpro Plus6.0.3.Immunohistochemical method was used to observe the expression of bone tissue in the condylar bone,and to compare the changes of the expression in different groups and at different time points in the same group.4.The experimental data were imported into spss17.0 software for statistical analysis and processing.Result:In this study,we successfully established a rat model of low estrogen ICR.1.The concentration of serum estradiol was detected by electrochemil-uminescence method:A: contraceptive group: after four weeks,the serum E2 concentration was no significant change in control group(P>0.05).But the eighth week,Twelfth weeks,the serum E2 concentration was significantly lower than the control group,the difference has statistical difference(P<0.05).B: premature ovarian failure group: The fourth week,eighth week and twelfth week,the serum E2 concentration of the rats was lower than that of the control group,and the result was statistically significant(P<0.05)2.The morphological changes of subchondral bone:The fourth week: compared with the control group,there was no significant difference between the two groups(p>0.05).The number and thickness of the trabecular bone and the width of the trabecular space(p<0.05)were increased in the POF group.The eighth and twelfth week: compared with the control group,oral contraceptive to trabecular number and thickness of group and group of POF bone were reduced,trabecular bone spacing widened(p<0.05)compared with the group at different time points,the trabecular bone data rebound,but the overall absorption >repair.3.The immunohistochemistry result showed that:TNF-a in cartilage mast cell showed positive in the subchondral bone,which also showed in the cartilaginous bone,and is stained with brown and yellow.After 4weeks,8 weeks,the expression rate of TNF-a was stable in the cartilage cells in the control group.Compared to the control group,the orally pill group and POF group showed high expression rate of positive cells(p<0.05),and the expression rate was increased with time.Conclusion:1 Under this experimental condition,oral contraceptive drugs within 4 weeks would not cause the rat serum low estrogen.But more than 4 weeks with Oral contraceptive drugs and injection of cisplatin may be one of the reasons lead to low serum estrogen.2 The lack of serum estrogen for a period of time may lead to the change of the bone morphology of the mandibular condyle and induce the degenerative changes of the condyle.3Estrogen regulates TNF-? and increases the expression of osteoclast activating factor TNF-?.