Sombuntham Nonglak P, Songwattana Siriwan, Atthakorn Phumvuth, Jungudomjaroen Sumon, Panyarachun Busaba
Orthodontic Section, Department of Pedodontics and Preventive Dentistry, Faculty of Dentistry, Srinakharinwirot University, Bangkok, Thailand.
Am J Orthod Dentofacial Orthop. 2009 Jul;136(1):75-82. doi: 10.1016/j.ajodo.2007.08.021.
In this preliminary study, we investigated early histologic changes of paradental tissues in response to a clear plastic appliance in rats.
Fifteen rats were divided into 3 groups. Group I was the untreated controls; group II received a clear plastic appliance made from a model, with the maxillary left first molar repositioned mesially 0.5 mm from the origin; and group III had a closed-coil spring to move the molar mesially. Specimens were prepared in parasagittal sections, and changes in paradental tissues were evaluated on days 1, 4, and 7 by light microscopy.
In group II, the periodontal ligament (PDL) was compressed in the bifurcation and apical areas of the roots of the molar. On day 7, the PDL of the apical and distal aspects of the roots and the bifurcation area showed further compression, with the PDL of the roots stretched along the mesial side. In group III, a disorganized and compressed PDL in the mesial cervical half and interradicular septum was observed, and the stretched fibers were at the distal aspects of the roots after days 4 to 7.
Early histologic changes in response to the clear plastic appliance were intrusion and distal tipping despite the intended mesial movement. In this rat model, the observed histologic changes were subject to the direction and magnitude of forces generated by the clear aligner.
在这项初步研究中，我们调查了大鼠牙周组织对透明塑料矫治器的早期组织学变化。
15只大鼠分为3组。第一组为未处理的对照组；第二组佩戴由模型制作的透明塑料矫治器，将上颌左侧第一磨牙从起始位置向近中重新定位0.5毫米；第三组使用闭合曲弹簧将磨牙向近中移动。制作矢状旁切片标本，在第1天、第4天和第7天通过光学显微镜评估牙周组织的变化。
在第二组中，磨牙牙根分叉和根尖区域的牙周膜（PDL）受到压缩。在第7天，牙根根尖和远中方面以及分叉区域的PDL显示出进一步压缩，牙根的PDL沿近中侧拉伸。在第三组中，在近中颈半和根间间隔观察到PDL紊乱和压缩，在第4至7天后拉伸的纤维位于牙根远中方面。
尽管预期是近中移动，但透明塑料矫治器引起的早期组织学变化是牙齿侵入和远中倾斜。在这个大鼠模型中，观察到的组织学变化取决于透明矫治器产生的力的方向和大小。
