First, without getting too stuck in the “science mud”, one must have a basic understanding of the biology behind tooth movement. Surprisingly, teeth, even though they appear to be static in the mouth, are in a constant state of flux. This occurs not only on a daily basis with chewing (teeth flexing in the sockets) but also throughout one’s lifetime: from early childhood with tooth eruption to late adulthood with dental arch changes. An important principle to remember is that teeth are programmed to respond to pressure and they will move if that pressure is maintained over a long enough period of time.

Let’s dive in a little deeper into the science of tooth movement. When a tooth receives an orthodontic force, it shifts in position and the periodontal ligament in the tooth socket is compressed in some areas and stretched in others. The compression / tension of the periodontal ligament immediately changes blood flow, oxygen levels and triggers the release of chemical mediators. As a result, special cells (osteoclasts) jump into action to remove bone in front of the compression side and others cells (osteoblasts) lay down new bone on the tension side. And voila, the tooth begins to move! If the orthodontic forces are too great, some cell death occurs in the compression side and tooth movement is impeded (up to 7-14 days) due the need to recruit adjacent cells. Ideally, light force application triggers the biological response needed to move teeth without creating excessive inflammation and cell death.