Research Summary

Orthodontics: What s going on under the gums

Although orthodontic braces apply constant force to teeth, researchers have found that the strain on gum tissue varies with time. To move teeth, orthodontists must apply just enough force to trigger remodelling of bone and gum tissues around tooth roots. However, these forces cannot be directly measured in living tissue. An international team at Texas A&M University in Dallas, US, and Sichuan University, China, led by Xiang-Long Han used molecular markers to reveal stress in the periodontal ligament, which attaches tooth roots to gum tissue. Using cultured cells and cells from rats undergoing orthodontic treatment, the researchers measured expression of the proteins alpha-smooth muscle actin, which enhances tissue contraction, and tenascin-C, which loosens tissue to prevent overstretching. Levels of both markers varied over time, corresponding to patterns of tooth movement.