Physiology of tooth movement Flashcards
what are the types of tooth movement?
Physiological
- tooth eruption
- mesial drift
orthodontic
- from externally generated forces
Briefly outline the physiological basis of orthodontics
if an external force is applied to a tooth, the tooth will move as the bone around it remodel
What structure mediates the remodelling of bone during orthodontic tooth movement?
the periodontal ligament
Give the 3 different theories for orthodontic tooth movement
- differential pressure theory
- mechano-chemical theory
- piezo-electric theory
Briefly describe the differential pressure theory
- in areas of compression, bone is resorbed
- in areas of tension bone is deposited
What are the types of tooth movement?
- tipping
- bodily movement
- extrusion
- intrusion
- rotation
- torque
What effects do moderate forces have when applied to a tooth?
- occlusion of vessels of PDL on pressure side
- hyperaemia of vessels of PDL on tension side
- cell free areas on pressure side
- relatively rapid movement of tooth with bone deposition on tension side
- tooth may become slightly loose
- healing of PDL leading to reorganisation and remodelling
What effects do excessive orthodontic forces have on a tooth?
- pain
- necrosis
- root resorption
- anchorage loss
- possible loss of tooth vitality
What factors affect the response a tooth may have to an orthodontic force?
- magnitude
- duration
- age
- anatomy
briefly outline the piezo-electric theory of orthodontic tooth movement
- piezo-electric currents are generated when crystalline structures, such as bone, are deformed
= currents are relatively short lived so unlikely to play a major role in bone remodelling
briefly outline the pressure-tension theory of orthodontic tooth movement
- alterations in blood flow in the PDL and/or release of chemical messengers from damaged cells leads to remodelling of the alveolar bone and tooth movement
- areas of compression bone is resorbed
- areas of tension bone is deposited
types of orthodontic appliances
- removable (URA)
- functionals
- fixed
What type of active tooth movement is achievable with an upper removable appliance?
tipping
How do functional appliances work?
- mandible is postured away from its normal rest position
- the facial muscles are then stretched which generates forces to the teeth and alveolar bone
What are functional appliances usually used to treat?
Class 2 div 1 maloclussion
