增龄性因素对正畸牙齿移动过程中牙髓组织变化的影响

发布时间：2018-05-09 10:49

本文选题：增龄 + 牙髓　；参考：《首都医科大学》2017年硕士论文

【摘要】：目的:观察不同年龄组大鼠正畸牙齿移动过程中牙髓组织HIF-1α、VEGF及细胞凋亡等的表达变化,探讨增龄性因素对这些因子及细胞凋亡的影响,从而进一步探究导致青少年及成人正畸差异的原因,为正畸临床操作提供理论依据。方法:选取SD雄性大鼠5周龄与8-9月龄各25只,建立正畸牙齿移动模型。两组大鼠均在实验加力1天、3天、7天、14天及28天时处死取材,通过HE染色及免疫组化染色、TUNEL染色等方法对上颌第一磨牙近中移动过程中牙髓组织的变化及HIF-1α、VEGF、细胞凋亡等表达情况进行观察。结论如下:1、青少年组与成年组大鼠均发生牙齿移动,但成年组牙齿移动速度较慢,移动距离较少。2、青少年组加力1天时牙髓组织即可观察到明显的血管扩张,新生血管形成等反应,3天时细胞增殖及聚集现象明显,14天时牙髓组织基本恢复正常;成年组加力3天时牙髓组织开始有血管扩张、组织水肿等表现,7天、14天时多细胞区面积明显增加,28天时除牙髓中部血管数量增多,其余结构基本恢复正常。由此可见,青少年组较成年组牙髓组织反应更迅速,代谢周期更短。3、青少年组实验侧牙髓组织HIF-1α表达自加力1天起开始增强,3天时表达至峰值,随后逐渐降低;成年组加力3天起牙髓组织HIF-1α表达逐渐增强,7天时表达至峰值,随后逐渐降低。我们推测增龄性因素可能使牙髓组织对缺氧调控的速率减慢,调控周期延长。4、青少年组加力1天开始牙髓组织VEGF表达逐渐增强,7天时表达量达峰值,随后逐渐降低;成年组加力3天开始牙髓组织VEGF表达逐渐增强、14天时表达量达峰值,随后表达逐渐降低。青少年组牙髓组织VEGF表达在1天、3天、7天、14天时均高于成年组,且差异具有统计学意义。我们推测增龄性因素使成年组大鼠牙髓组织VEGF表达增加缓慢,且表达量降低,从而导致牙髓组织对正畸力的反应较为滞后,反应周期延长。5、青少年组加力3天时牙髓内细胞凋亡率显著增高,随后逐渐降低,14天时细胞凋亡率与对照组无明显差异;成年组加力3天开始细胞凋亡率逐渐增加,7天时达峰值,随后逐渐下降;成年组牙髓组织细胞凋亡率在各个时间点均高于青少年组,差异具有统计学意义。我们推测增龄性因素使牙髓组织细胞凋亡率增高,但细胞凋亡调节周期延长。正畸牙齿移动过程中牙髓组织通过启动细胞凋亡来保持细胞繁殖和细胞死亡之间的平衡,及时清除无用和有害的细胞,从而调节细胞数量,维持牙髓组织内环境稳定。
[Abstract]:Objective: to observe the expression of HIF-1 伪 -VEGF and apoptosis in dental pulp tissue during orthodontic tooth movement in rats of different age groups, and to explore the effect of aging factors on these factors and apoptosis. So as to further explore the causes of orthodontic differences between adolescents and adults, and provide theoretical basis for orthodontic clinical operation. Methods: 25 SD male rats aged 5 weeks and 8 to 9 months old were selected to establish orthodontic tooth movement model. The rats of both groups were killed at 1 day, 3 days, 7 days, 14 days and 28 days, respectively. The changes of pulp tissue and the expression of HIF-1 伪 -VEGF and apoptosis during the proximal movement of maxillary first molar were observed by means of HE staining and immunohistochemical staining with Tunel staining. The results showed that tooth movement occurred in both adolescent and adult groups, but tooth movement in adult group was slower and movement distance was less than that in adult group. Significant vasodilation was observed in dental pulp tissue of adolescent group after one day of exertion. The phenomenon of cell proliferation and aggregation was obvious at the 3rd day of neovascularization, and the pulp tissue returned to normal on the 14th day, and the dental pulp tissue began to dilate at the 3rd day after adding stress in the adult group. Tissue edema showed that the area of multicellular area increased significantly at day 14 after 7 days, except the number of blood vessels in the middle of dental pulp increased, and the other structures returned to normal basically at 28 days. It can be seen that the reaction of pulp tissue in juvenile group is faster than that in adult group, and the metabolic cycle is shorter. The expression of HIF-1 伪 in experimental pulp tissue of juvenile group has been increased to its peak value at 3 days since the first day of adding force, and then decreased gradually. In adult group, the expression of HIF-1 伪 increased gradually at 7 days and then decreased gradually. We speculate that aging factors may slow down the rate of hypoxic regulation in dental pulp tissue, and prolong the control cycle by .4. the expression of VEGF in dental pulp tissue of adolescent group increases gradually at day 7 and then decreases gradually at day 7. In adult group, the expression of VEGF increased gradually at day 14 and then decreased gradually at day 14. The expression of VEGF in dental pulp tissue of adolescent group was higher than that of adult group at day 1, day 3, day 7 and day 14, and the difference was statistically significant. We speculate that aging causes the expression of VEGF to increase slowly and decrease in adult group, which leads to the delayed response of dental pulp to orthodontic force. When the reaction cycle was prolonged, the apoptosis rate of dental pulp cells in the juvenile group increased significantly after 3 days of stress, and then decreased gradually at 14 days. There was no significant difference between the juvenile group and the control group at 14 days. The apoptosis rate of adult group increased gradually at 7 days and then decreased gradually. The apoptosis rate of dental pulp tissue in adult group was higher than that in juvenile group at each time point, and the difference was statistically significant. We speculated that aging factors increased the apoptosis rate of dental pulp cells, but prolonged the apoptosis regulation cycle. In the process of orthodontic tooth movement, pulp tissue keeps the balance between cell proliferation and cell death by initiating apoptosis, and removes useless and harmful cells in time, thus regulating the number of cells and maintaining the stability of dental pulp tissue environment.
【学位授予单位】：首都医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R783.5

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