| Objectives Through establish of experimental animal model of Wistar rats in lactation period, to test 1 bone mineral density(BMD) of proximal tibia and the first molar mobile distance on different lactation stage after orthodontic stress application; 2 the expression situation of vascular endohtelial growth factor(VEGF) in periodontal tissue cells after orthodontic stress application of rats. To discuss the changes of BMD and proximal tibia on first molar mobile distance of lactation rats, and the different expression of VEGF effect on periodontium re-construction, and to provide experimental reference for female patients in lactation period.Methods 60 Female Wistar rats and 30 male rates, 3 months’ old, 220±20g, SPF grade, breeding fodder feeding. 60 female rats were divided with random number table method into(A)control group,(B)lactation group,(C)stress application group,(D) lactation with stress application group, 15 in each group. Each group was divided into three sub-groups based on the periods of 7 days, 14 days and 21 days, with 5 in each sub-group. B and D was established the model of rats in lactation. C and D was installed the orthodontic device between the first molar and incisor tooth at right side of the maxillary of the rats, and the rats were killed on the last day of various periods. The left tibia was got, to test the BMD in the proximity and measure the first molar mobile distance. The first molar and the surrounding periodontium of the right maxillary were got to make the histologic sections on mesiodistal direction after 4% paraformaldehyde fixed and 10% EDTA decalcification, and VEGF immunohistochemical(IHC) staining were conducted. The Image-Pro Plus 5.0 software was utilized to conduct semi-quantitative analysis to the expression situation of VEGF at the tension side of the first molar. The statistical analysis to mean optical density(MOD) of VEGF expression of periodontal cell was conducted on the basis of histological observation and image analysis.Results 1 The bone mineral density of the proximal tibia of lactation group rats were lower than control group rats(P<0.05). The BMD of rats in lactation period reduced with the extension of lactation time(P<0.05). The difference was statistically significant.Orthodontic force had no obvious influence to the change of BMD(P>0.05). 2 Orthodontic tooth movement of rats in lactation were higher than control group rats(P<0.05). Orthodontic tooth movement of rats in lactation period increased with the extension of lactation time(P<0.05). The difference was statistically significant. 3 According to the IHC result, there were VEGF positive expressions in periodontium of rats of different groups, and the main expression parts were the cytoplasm of PDLF, VEC,OB and OC. 4 No matter stress application or not, the expression of VEGF in periodontium of lactation group rats were higher than control group rats(P<0.05). The difference was statistically significant. Stress application can result in the strengthening of VEGF expression of periodontium of the tension side of stress application rats and lactation with stress application rats, which achieved the peak at 14 d, and then gradually lowered down, and the difference was statistically significant(P<0.05).Conclusion 1 BMD of the proximal tibia of lactation group rats are lower than control group rats. Orthodontic tooth movement of rats in lactation with stress application group were higher than stress application rats. 2 The expression of VEGF in periodontium at the tension side of lactation rats are higher than control group rats. Stress application can result in the strengthening of VEGF expression of lactation rats, which prompts that VEGF participates in the process of reconstruction of orthodontic periodontium. |
PDF Full Text Request