References-Ghoms Textbook of oral medicine 2nd edition


Continuous force- active force that decreases little in magnitude betwwen appointments.

  • Light weight appliances
  • Highly flexible appliance components used which are activated at low force level.
  • No interference with biological function and no harm to soft tissues.
  • Direct resorption of bone

Intermittent force- active force that decays to zero before next appointment.

  • High stiffness appliances
  • Twice the force activation for corresponding soft tissue deformation
  • Undermining resorption and corresponding tooth movement.

Interrupted force- inactive for intervals of time between appointments

  • Cyclic, long term magnitude time pattern
  • Heavy forces delivered
  • No force decay

Reference- orthodontics bhalajhi


Can be categorized into 3 categories-

  • Pure translation- intrusion and extrusion, bodily movement
  • Pure rotational- torquing and tipping
  • Generalized rotational

1. Tipping- single force applied results into movement of crown in direction of force and movement of root in opposite direction.

A) Controlled tipping- When tooth tips about centre of rotation at apex. Lingual movement of crown with minimal movement of root in opposite direction.

B) Uncontrolled Tipping- when movement of tooth occurs about centre of rotation close to centre of resistance. Crown moves in lingual direction and root in opposite direction.

2.Torquing – reverse tipping characterized by lingual movement of root.

3. Bodily movement- All points on tooth will move equal distance in the direction of applied force. Line of action of force is through centre of resistance.

3. Intrusion- bodily displacement of tooth in apical direction along longitudinal axis of tooth.

4. Extrusion- bodily displacement of tooth in coronal direction along longitudinal axis of tooth.

5. Rotational- labial or lingual movement of tooth around long axis

6. Uprighting- when crowns are tipped in mesiodistal direction roots tipped in opposite direction. Tipping the roots back to get parallel orientation is called uprighting.

Reference- ortho bhalajhi