Physiology of Tooth movement and appliances Flashcards
Describe differential pressure theory in brief terms
In areas of compression, bone is resorbed.
In areas of tension, bone is deposited.
What do osteoblasts do in areas of compression?
Osteoblasts bunch up together and expose osteoid layer, giving osteoclasts access to resorb the bone.
Osteoblasts send signals (e.g. RANKL) to recruit and activate osteoclasts.
What do osteoblasts do in areas of tension?
Osteoblasts are flattened covering the osteoid layer and preventing osteoclasts from gaining access to the bone.
Osteoblasts secrete organic matrix and hydroxyapatite crystals to form bone.
What are the different types of tooth movement?
Tipping
Bodily movement
Intrusion
Extrusion
Rotation
Torque
What degree of force is required for tipping movement?
35-60g
What degree of force is required for bodily movement?
150-200g
What degree of force is required for intrusion?
10-20g
What degree of force is required for extrusion?
35-60g
What degree of force is required for rotation?
35-60g
What degree of force is required for torque?
50-100g
How is it thought that functional appliances work?
(ones that correct class II malocclusions)
The facial musculature is stretched which generates forces that are transmitted to teeth.
How long does a twin block typically take to work?
6-12 months
What is a common unwanted, consequence of a twin block?
They create a lateral open bite
How does the PDL stay the same size in bodily movement of teeth?
Secondary re-modelling - bone is deposited on the opposite side from resorption
Why do teeth often relapse post-ortho treatment?
Gingival fibres do not re-order/ remodel in the same way that periodontal fibres do, remain distorted after being moved through orthodontics.
If retainers aren’t worn, teeth will often relapse to old position.
