The Effects Of Oral Contraceptives On Periodontal Tissue Reconstruction During Orthodontic Tooth Movement In Rats

Objective: The biological basis of orthodontic tooth movement is the reconstruction of periodontal tissue which is under the action of orthodontic force.When the orthodontic force applied to teeth,periodontal tissue such as periodontal ligament and alveolar bone will change this mechanical stimulus into a biological signal,and then it will pass the signal transmission and create the corresponding biochemical reactions which were induced in the osteoblast and osteoclast to reconstruct the periodontal tissue.The process of periodontal tissue reconstruction is affected by systemic factors and local factors based on the molecular level.The estrogen and progesterone play an important role in the process of periodontal tissue reconstruction among them.With the people's awareness of the pursuit of beauty strengthened,adult women have become the second largest group of orthodontic patients.Because of the influence of all of life,work,family and other factors,some women chose oral contraceptives to prevent pregnancy.Oral contraceptive is also used in the treatment of women adolescent acne,endometriosis,endometrial hyperplasia and menstrual disorders and other diseases.The main component of oral contraceptives are estrogen and progesterone.And this exogenous intake of sex hormones will slow down the rate of orthodontic tooth movement.So,the aim of this study was to analyses the effects of oral contraceptives Marvelon on periodontal tissue reconstruction during orthodontic tooth movement in rats.Methods: Eighty adult female SD rats(three-month-old)were divided into control group and experimental group randomly and 40 rats in each group.Rats of each group were divided into four subgroups and 10 rats in each subgroup.In experimental group,rats were given 0.12 mg /d Marvelon by gavages;meanwhile rats in control group were given an equivalent volume of Saline.All the rats were equipped with a orthodontic force device exerting 50 g force and maxillary central incisors were bundled to move the first molar.7,14,21 and 28 days after orthodontic force exerting animals were sacrificed.The expression of estrogen receptors(ER)and osteoprotegerin(OPG)in periodontal tissue were measured by immunohistochemical staining.The data were analyzed by independent sample t-test and one-way ANOVA.Results:(1)Compared with control group,the expression of ER in experimental group was decreased(P<0.05).(2)The expression of ER in both control group and experimental group declined from the 7th to 14 th day,and recovered in 21 st and 28 th days(P<0.05).(3)Compared with control group,the expression of OPG in experimental group was increased(P<0.05).(4)The expression of OPG in control group was on the rise from the 7th to 14 th day,and fell back in 21 st and 28 th days(P<0.05).(5)There's no significant differences among the expression of OPG in experimental group at the four time points(P>0.05).Conclusion:(1)The oral contraceptives Marvelon can decrease the expression of ER in periodontal tissue of SD rats.(2)Marvelon won't change the expression rhythm of ER in periodontal tissue.(3)Marvelon can increase the expression of OPG in periodontal tissue.(4)Marvelon can break the expression rhythm of OPG in periodontal tissue.