Department of Orthodontics and Pediatric Dentistry, School of Dentistry, The University of Michigan, Ann Arbor, MI 48109-1078, USA.
Calcif Tissue Int. 2012 Apr;90(4):330-42. doi: 10.1007/s00223-012-9579-4. Epub 2012 Mar 1.
Relapse after orthodontic tooth movement is a significant problem in orthodontics. The purpose of this study was to examine the efficacy of the osteoclast inhibitor osteoprotegerin-Fc (OPG-Fc) for inhibiting postorthodontic relapse. Rat maxillary molars were moved mesially and allowed to relapse for 24 days. Low-dose (1 mg/kg) or high-dose (5 mg/kg) OPG-Fc or saline was injected adjacent to the molars during relapse. Tooth movement, micro-CT, histologic bone quality, and serum OPG and TRAP-5b were measured. OPG-Fc injections significantly diminished postorthodontic relapse from 63% (0.78/1.20 mm) of total movement in vehicle control rats to 31% (0.31/1.00 mm) in low-dose and 24% (0.28/1.16 mm) in high-dose OPG-Fc groups 24 days after appliance removal. Normalization of bone and periodontal tissues occurred as early as 8 and 16 days in the high- and low-dose OPG-Fc-treated groups, respectively, while the vehicle-treated group showed only partial tissue recovery 24 days following tooth movement. After 24 days of relapse, there was complete recovery to pre-tooth-movement values for bone volume fraction (BVF) and tissue mineral density (TMD) in both the low- and high-dose OPG-Fc groups, while BVF recovered only partially and TMD did not recover in the vehicle control group. Greatly elevated serum OPG levels and reduced serum TRAP-5b levels in OPG-Fc-treated animals indicated systemic exposure to locally injected drug. The profound decrease in postorthodontic relapse by local OPG-Fc administration indicates that osteoclasts are critical to bone maturation following tooth movement and points to the potential pharmacologic use of OPG-Fc or other RANKL inhibitors for orthodontic retention.
正畸牙齿移动后的复发是正畸学中的一个重大问题。本研究旨在研究破骨细胞抑制剂骨保护素-Fc（OPG-Fc）抑制正畸后复发的效果。将大鼠上颌磨牙向近中移动，然后允许其复发 24 天。在复发期间，将低剂量（1mg/kg）或高剂量（5mg/kg）的 OPG-Fc 或生理盐水注射到磨牙附近。测量牙齿移动、微 CT、组织学骨质量以及血清 OPG 和 TRAP-5b。OPG-Fc 注射可显著减少正畸后复发，从载体对照大鼠中 63%（0.78/1.20mm）的总移动量减少到低剂量组的 31%（0.31/1.00mm）和高剂量组的 24%（0.28/1.16mm），在去除矫正器 24 天后。高剂量和低剂量 OPG-Fc 治疗组分别在 8 天和 16 天即可使骨和牙周组织正常化，而载体处理组仅在牙齿移动后 24 天显示部分组织恢复。在复发 24 天后，低剂量和高剂量 OPG-Fc 组的骨体积分数（BVF）和组织矿物质密度（TMD）均完全恢复到牙齿移动前的水平，而载体对照组仅部分恢复 BVF，TMD 未恢复。OPG-Fc 治疗动物的血清 OPG 水平显著升高，血清 TRAP-5b 水平降低，表明局部注射药物的全身暴露。局部 OPG-Fc 给药显著降低正畸后复发率，表明破骨细胞对于牙齿移动后的骨成熟至关重要，并表明 OPG-Fc 或其他 RANKL 抑制剂在正畸保持方面具有潜在的药理学用途。
