How Teeth Move


Orthodontic tooth movement is a complex physical, biochemical, and cellular process.

All healthy teeth are surrounded by a thin blanket of connective tissue called the periodontal ligament (PDL). The ligament is bordered on one side by the tooth and on the other side by alveolar bone (dental bone).

Many of the cells in the PDL are called osteocytes (bone cells). These cells can change themselves, if signaled biochemically to, into bone forming cells called osteoblasts, or bone removing cells called osteoclasts.

When a force is placed against a tooth with braces (see parts of braces) the tooth is forced away from the bone. The side of the tooth in the direction it is moving is called the pressure side. The opposite side is called the tension side.

The pressure side compresses the PDL and a biochemical reaction occurs, and osteoclasts (bone removing cells) are formed from osteocytes (bone cells). Bone on the pressure side is then removed. On the tension side, osteocytes will form osteoblasts (bone forming cells). Hence, bone is removed on one side and replaced on the opposite side.

The forces used to move teeth are very light. Even though the forces are gentle, the teeth will get sore for a few days. After this period of time, the soreness will subside.