Page 16 - REMOVABLE ORTHODONTIC APPLIANCES
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Chapter 2
Biomechanics of tooth movement
When a force is applied to the crown of a tooth, An understanding of these processes is of
it will be displaced slightly within the confines clinical relevance in that the rationale of appli-
of the periodontal ligament. Depending on the ance adjustment is based on our knowledge of
type of force applied, the tooth may be tipped, them.
moved bodily, or rotated about its long axis
(Figure 2.1). This small change in tooth posi-
tion will set up areas of tension and compres- Tooth movements
sion within the periodontal ligament. Provided
that the force is applied over a sufficient period When a force is applied to a point on a smooth
of time, remodelling of the socket wall will surface, it can be resolved into two compo-
allow the tooth to move further. nents, one at right angles to the surface and the
Figure 2.1 Three kinds of tooth movement.
(a) Tipping, (b) Bodily movement, (c) Rotation
about the long axis.
