Forces moving teeth Flashcards
What are the 2 types of tooth movement?
Physiological tooth movement (eruption)
Orthodontic from externally generated forces
What are the stages in tooth eruption?
- pre-eruptive tooth movement (small, random)
- intra-osseous eruption (after crown forms, slow) aka erupting through the bone
- mucosal penetration (fast)
- pre-occlusal eruption (slow)
- post occlusal eruption (very slow)
Why is the dental follicle important for tooth eruption?
Its important for bone resoprtion
What other factors are important for eruption?
Deciduous tooth resorption
Apical blood flow
How can interceptive ortho treatment help ectopic canines?
Interceptive extraction of the deciduous canines at the correct stage
When is the right time/correct stage to interceptively extract deciduous canines to help treat ectopic canines?
When the permanent has 1/2-2/3rds of roots development
Pateint will be between 10-12
When should GPD’s be looking for ectopic canines? Why is it important to refer then?
Around age 9 and refer
Because if dont extract on time will need surgery to move them
What is the physiological basis of orthodontics? e.g. how does the tooth move
If an external force is applied to a tooth, the tooth will move as the bone around it remodels
The bony remodelling in orthodontic tooth movement is mediated by what?
The PDL
When will a tooth note move?
If it doesnt have a PDL or is ankylosed
What role does cementum play in tooth movement? (how is it affected?)
Cementum is muchmore resisitant to resorption than bone, although some degree of root resorption after orthodontics should be expected
If there was no cementum then teeth would exfoliate post treatment
Appliances transmit forces to the PDL and bone and osteoclasts ‘herd’. What happens if there is an osteoclast that isnt working optiminally?
Macrophage will phagocytose
What are the different theries for how orthodontic tooth movement occurs?
- differential pressure theory
- piezo-electric theory
- mechano-chemical theory
Describe the differential pressure theory.
You get tension on one side where there is bone deposition
Get compression on other side/parts and get resorption from osteoclasts here
Describe the piezoelectric current theory.
-piezoelectric currents are generated when crystalline structure, such as bone, are defomed
These currents have been suggested as the prime mechanism by which tooth movement is modulated
Describe the mechano-chemical pressure theory.
mechanical stress
- release of neuropeptides from nerve endings
- stimulate fibroblasts, endothelial cells and alveolar bone
- fibroblasts also communicate with osteoblasts and osteoclasts
- alveolar bone and PDL remodelling
- tooth movement
What are the diff types of ortho appliances? (3)
- removables
- functional
- fixed
What are the different types of tooth movement?
- tipping
- bodily movement
- intrusion
- extrusion
- rotation
- torque (is like tipping but moving the root instead of the crown)
What is the ideal force tot tip a tooth? (exam Q)
35-60 grams
What are functional orthodontic appliances used to treat?
To correct class II occlusions (bring the mandible forward)
How do functional appliances work?
- The mandible is postured away from its normal rest position
- the facial musculature is stretched which generated forces transmitted to the teeth and alveolus
- there may be an effect on facial growth