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
Reference- Carranza’s Clinical periodontology
Reference- carranza’s clinical periodontology 3rd south asian edition
Reference- Carranza’s clinical periodontology 3rd south asian edition
Reference- Neelima Malik oral surgery
Handbook of local anaesthesia by Stanley F. Malamed