Tooth Movement: Mechanics and Types
Tooth Movement in Orthodontics is basically a response to the appliance that has been used for the movement of tooth and this Tooth Movement mainly occurs at three levels i.e. clinical, cellular and within the investing tissues.
The main factor that is responsible for Tooth Movement is the force and it changes the position of tooth depending upon the magnitude of it and the time for which it is being used.
Types of Forces
Based on the duration of application and the magnitude of the force, it is of three types mainly:
1. Continuous Force
This is an active orthodontic force that decreases little in magnitude between the different appointments and thus the force magnitude should be according to the requirement so that there occurs no tissue damage and the example of this force to bring about Tooth Movement is the Light wire appliance.
2. Intermittent Force
This is an active orthodontic force that bring about the Tooth Movement by applying the large amount of force magnitude that decays to zero when the next appointment time comes nearby and the example of it is Removable active plates.
3. Interrupted Force
It is an orthodontic force that is inactive for intervals of time between appointments and these force containing appliances should preferably be worn at night time. The example of interrupted force to bring about the Tooth Movement is the Extra oral appliance.
Types of Tooth Movement
• Tipping
It is a simple type of Tooth Movement where the movement results due to the application of just a single force. In this Tooth Movement there occurs movement depending upon which point of the tooth is acted upon by the force. Like if the centre is tip of root then the root will move in the direction of force applied and the crown will move in the opposite direction of it.
• Bodily Movement
But if the force is applies to its centre of resistance then there will be same Tooth Movement in the whole tooth i.e. the crown and root will both move in one direction.
• Intrusion and Extrusion
Intrusion is the Tooth Movement along the axis of the tooth and the result will be the inward movement of the tooth inside the socket. On the other hand, Extrusion is the outward Tooth Movement from the socket when the force is applied along its axis.
• Rotation
Rotation is the Tooth Movement when the force is applied along its long axis and the result is that the tooth can be moved along the buccal or lingual side.
• Torquing
It is the Tooth Movement that is just reverse to tipping movement of the teeth.
