Biology of Tooth Movement

maturational shortening of collagen fibers which can cause teeth to move

• Shock Absorber
• Heavy for <1 sec: alveolar bone bends. Piezo electric currents stimulate skeletal regen/repair
• Constant pressure: fluid rapidly leaves (after 3-5 sec w/ pain). causes remodeling of bone.

• Pressure-Tension theory: chemical signals act as a stimulus for tooth movement.
• 3 stages
• 1. alteration in blood flow associated with pressure w/i the PDL
• 2. release of chemical messengers
• 3. activation of cells

heavy forces causing necrosis of cellular elements of PDL. minimal tooth movement during a lag phase.

light pressures to move teeth used in ortho where the cells of the PDL survive. osteoclasts remove bone in pressure area and build bone on tension side.

one point of force applied at the crown of the tooth, tooth rotates around center of resistance. pdl is compressed near apex and opposite side of the force. force shouldn't exceed 60g

2 forces applied simultaneously so the PDL is loaded uniformly. twice as much force is required as tipping (120g).

• 1. abnormal tooth morphology
• 2. prolonged ortho forces
• 3. genetic predisposition

resistance to unwanted tooth movement.

reciprocal: forces applied to teeth are equal and so is force distribution in the PDL. larger tooth has larger area for force distribution

differential: tooth movement increases as pressure increases up to a point and may actually decline with extreme heavy pressure. more teeth in the anchor unit = more pressure.

adding more resistance units is effective bc more teeth are in anchorage with distributes the force over a larger PDL area.

at the apex

slightly apical to Cres

Crot infinity

incisal edge

force acting at a distance from the Cres. produced when a force will cause some rotation. potential for rotation is measured as a moment.

two forces equal in magnitude and opposite in direction that are parallel and non-colinear. only a couple can produce pure rotation, no single force can produce a pure rotation

Translation/Bodily Movement. no rotation.