Tooth movement and appliances Flashcards
what is described in the aim of an ortho URA prescription sheet
description of what the APPLIANCE is aiming to achieve
Not the aim of the whole treatment
what process does tooth movement via orthodontics rely on
bone remodelling by osteoclasts and osteoblasts which is controlled by PDL fibres
if a prolonged force is applied, tooth movement will occur
differential pressure theory of orthodontic tooth movement
applying force to the crown creates stresses in the periodontal ligaments
Compression areas see bone resorption and tension areas see bone deposition
mechano-chemical theory of orthodontic tooth movement
cells (osteoblasts) undergo shape changes in response to tension and pressure
Compression areas see osteoblasts bunched up exposing osteoid layer to osteoclasts resulting in resorption
Tension areas see osteoblasts stretched and flattened preventing osteoclasts reaching the osteoid layer and allowing for bone deposition to occur
what movement can removable appliances create
tipping of teeth
example of a functional appliance
twin block
what patients might be given a functional appliance
patients with skeletal discrepancies who are still growing
(must be still growing for them to work)
what force is required to tip teeth
dependent on size of tooth , 35-60g
what is bodily movement of a tooth and how much force is required for this to be done
bodily movement is moving the whole tooth, crown and root, as one. Requires a fixed appliance
force required in 150-200g
what force is required to intrude teeth and why is it so low
10-20g
high forces would risk root resorption
what force is required to rotate teeth
35-60g
what force is required to extrude teeth
35-60g
what is torque movement of a tooth and how much force is required to do this
torque refers to moving the root of the tooth with minimal movement of the crown
requires force of 50-100g
what change to blood flow is caused by orthodontics using light pressure
hyperaemia in pressure and tension areas
(increased blood flow)
what happens to PDL and gingival fibres when a tooth is moved orthodontically using light pressure
the PDLs have enough time to reorganise
Gingival fibres remain distorted and dont reorganise - a main reason for relapse post treatment if a retainer isnt worn