Department of Restorative Destistry, Faculty of Dentistry, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Department of Pediatric Dentistry, Faculty of Dentistry, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Arch Oral Biol. 2020 Sep;117:104820. doi: 10.1016/j.archoralbio.2020.104820. Epub 2020 Jun 18.
Root resorption is a side effect of orthodontic tooth movement (OTM). Despite the recognized role of estrogen on bone, there is little information about their effects on orthodontic-induced inflammatory root resorption (OIIRR). We aimed to investigate if estrogen deficiency affects OIIRR in two mice strains.
Female Balb/C (Balb) and C57BL6/J (C57) mice were ovariectomized (OVX) and replaced with estradiol (E2). Tooth samples subjected or not to OTM were collected and analyzed by microCT, histomorphometry and qPCR.
OVX resulted in decreased root volume (RV/TV) and root mineral density (RMD) in Balb mice without OTM. In contrast, OVX did not modify physiological root structure of C57 mice. OTM and OIIRR were increased after OVX in both mice strains after 30 days. E2 replacement reversed this phenotype in Balb, but not in C57 mice. Due to the significant increase of OIIRR in OVX Balb mice, the expression of key molecules was investigated in periodontium. Accordingly, these mice showed increased expression of receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor alpha, matrix metalloproteinases-2 and -13 and decreased osteoprotegerin (OPG) and interleukin-10 expression after OTM. E2 replacement reversed the changes of these markers.
The lack of estrogen in Balb mice without OTM triggered loss of root structure which was positively correlated to RANKL/OPG ratio. Regardless of mouse strain, the absence of estrogen following OTM induced OIIRR. Mechanisms involve the imbalance of RANKL/OPG system, inflammatory and osteoclastic makers.
牙根吸收是正畸牙齿移动（OTM）的副作用。尽管雌激素对骨骼的作用已得到公认，但关于其对正畸诱导的炎症性牙根吸收（OIIRR）的影响的信息却很少。我们旨在研究雌激素缺乏是否会影响两种小鼠品系的 OIIRR。
雌性 Balb/C（Balb）和 C57BL6/J（C57）小鼠接受卵巢切除术（OVX）并用雌二醇（E2）替代。收集并通过 microCT、组织形态计量学和 qPCR 分析未进行 OTM 或进行 OTM 的牙齿样本。
OVX 导致 Balb 小鼠未进行 OTM 时根体积（RV/TV）和根矿物质密度（RMD）降低。相比之下，OVX 未改变 C57 小鼠的生理性牙根结构。在两种小鼠品系中，OVX 后 30 天进行 OTM 和 OIIRR 增加。E2 替代仅在 Balb 小鼠中逆转了这种表型，但在 C57 小鼠中没有。由于 OVX Balb 小鼠 OIIRR 显著增加，因此在牙周组织中研究了关键分子的表达。相应地，这些小鼠在 OTM 后表现出核因子κB 受体激活剂配体（RANKL）、肿瘤坏死因子-α、基质金属蛋白酶-2 和 -13 的表达增加，而骨保护素（OPG）和白细胞介素-10 的表达减少。E2 替代逆转了这些标志物的变化。
在未进行 OTM 的 Balb 小鼠中缺乏雌激素会触发牙根结构丧失，这与 RANKL/OPG 比值呈正相关。无论小鼠品系如何，OTM 后缺乏雌激素都会引起 OIIRR。机制涉及 RANKL/OPG 系统、炎症和破骨标志物的失衡。
