State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, #14, 3rd Section, South Renmin Road, Chengdu, 610041, People's Republic of China.
The Affiliated Stomatology Hospital, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, People's Republic of China.
Prog Orthod. 2022 Jan 3;23(1):1. doi: 10.1186/s40510-021-00394-0.
Constricted maxillary bone is a common skeletal deformity, which may lead to crowding and posterior crossbite. Mid-palatal suture expansion is often used to increase the maxillary width, but its skeletal effects are limited and tend to relapse, even with prolonged retention. We hypothesized that parathyroid hormone (PTH) may reduce the relapse of maxillary expansion.
We established a novel rat maxillary expansion model using palatal tubes with an insertable "W"-shaped spring which can be repeatedly activated. A total of 32 male healthy Wistar rats were randomly divided into six groups: the control group, the PTH group, the expansion group, the expansion + PTH group, the expansion + relapse group and the expansion + PTH + relapse group. All animals in the first 4 groups were killed after 10 days and the 2 relapse groups were killed after 15 days. The maxillary arch widths and histological staining were used to assess the expansion and relapse effects. The immunohistochemical staining, micro-CT, RT-qPCR and Western blot were used to evaluate the bone remodeling during expansion.
The suture width was increased by the expansion device, and the repeated activation maxillary expansion rat model showed better expansion effects than the conventional model. PTH significantly promoted the expansion width and reduced the relapse ratio. Meanwhile, in the expansion + PTH group, histological and immunohistochemical staining showed that osteoblasts, osteoclasts, new cartilage and osteoid were significantly increased, micro-CT showed increased bone mass, and PCR and Western blot results confirmed up-regulation of RANKL, β-catenin, type II collagen and OCN.
The novel repeated activation maxillary expansion rat model has better effects than the conventional model. PTH enhances the maxillary expansion and reduces its relapse by regulating Wnt/β-catenin and RANKL pathways. PTH administration may serve as an adjunctive therapy in addition to mechanical expansion for treatment of maxillary constriction.
上颌骨狭窄是一种常见的骨骼畸形，可能导致拥挤和后牙反合。中缝扩展常用于增加上颌宽度，但它的骨骼效果有限，且有复发倾向，即使延长保持期也是如此。我们假设甲状旁腺激素（PTH）可能减少上颌扩张的复发。
我们使用带有可重复激活的“W”形弹簧插入物的腭管建立了一种新型大鼠上颌扩张模型。总共 32 只雄性健康 Wistar 大鼠被随机分为六组：对照组、PTH 组、扩张组、扩张+PTH 组、扩张+复发组和扩张+PTH+复发组。前 4 组的所有动物在 10 天后处死，2 个复发组在 15 天后处死。使用上颌弓宽度和组织学染色评估扩张和复发效果。免疫组织化学染色、微 CT、RT-qPCR 和 Western blot 用于评估扩张过程中的骨重塑。
扩张器增加了缝宽度，重复激活上颌扩张大鼠模型显示出比传统模型更好的扩张效果。PTH 显著促进了扩张宽度，降低了复发率。同时，在扩张+PTH 组中，组织学和免疫组织化学染色显示成骨细胞、破骨细胞、新软骨和类骨质明显增加，微 CT 显示骨量增加，PCR 和 Western blot 结果证实 RANKL、β-连环蛋白、II 型胶原和 OCN 上调。
新型重复激活上颌扩张大鼠模型比传统模型效果更好。PTH 通过调节 Wnt/β-连环蛋白和 RANKL 通路增强上颌扩张并减少其复发。PTH 给药可能作为机械扩张的辅助治疗，用于治疗上颌狭窄。
