Tooth Movement Flashcards
What are 7 factors for tooth positioning
Tooth size
Size of jaw
Presence of predecessor
Loss of predecessor
Tooth wear
Physiological mesial drift
Periodontal disease
What are the 3 phases of tooth movement
Pre eruptive phase
Eruptive pre functional phase
Post eruptive phase
What is the pre eruptive phase
The movement of the tooth germ - an aggregate of embryonic cells that will eventually form tooth
During eruption what type of tooth movement is it
Axial movement mainly hormone control
What can erupting teeth be affected by
Light intermittent forces such as muscular or soft tissue contact
Digit sucking or tongue thrusting
How do teeth move
Remodelling of bone and periodontal ligament take place
Bone resorbs on pressure side of tooth and is deposited on tension side
Usually as remodelling of PDL and bone occur tooth remains intact but some root resorption occurs
What do osteoblasts do
Deposit bone
What do osteoclasts do
Resorb bone
What do osteoblasts remove
Un mineralised collagen/osteoid that lines bone surface which acts as physical barrier to osteoclasts
What do osteoblasts release
Soluble activating factor which has direct action on osteoclasts
What is the pressure tension theory
Forced applied to tooth - bone laid down on tension side or bone resorbed on pressure side - tooth moves
What happens to tooth movement with light pressure side
Multinucleate cells resorb bone directly
What happens to tooth movement with light tension side
Blood flow is activated where PDL is stretched
Promotes osteoblastic activity and osteoid deposition
Osteoid mineralises to form new bone
What happens to tooth movement with heavy pressure side
Compression of PDL
Disturbance of blood flow in compressed PDL
Cell death in compressed area of PDL (hyalinisation)
Resorption of hyalinised tissue by macrophages
Undermining bone resorption by osteoclasts adjacent to hyalinised tissue
Tooth movement
What happens to tooth movement in heavy tension side
Blood flow is activated where PDL is stretched
Promotes osteoblastic activity and osteoid deposition
Osteoid mineralises to form new bone
What is the piezoelectric theory
When a force is applied to a tooth it will move within PDL but some deflection of bone also occurs producing stress generated electric potentials at bone surface
These forces are short lived and are unlikely to play an active role in bone remodelling
What does cell shape change have to do with tooth movement
Relationship between cell shape and metabolic activity
When a cell is distorted receptors are activated which initiates a cascade of chemical events
What happens as a result of mechanical stimulus in tooth movement
Acute inflammatory response in periodontal tissues
Triggers a cascade of biological events
What 7 biological responses are released and responsible for initiating bone remodelling and tooth movement
Neurotransmitters
Arachidonic acid
Growth factors
Metabolites
Cytokines
Colony stimulating factors
Enzymes
What are the 3 categories for post eruptive tooth movement
Accommodates tooth position within growing jaw, especially height
Compensates for occlusal wear
Accommodates interproximal wear
What does it mean to accommodate tooth position within growing jaws, especially height
Readjustment of position of tooth socket by bone remodelling
What does it mean to compensate for occlusal wear
Continues cementum formation at root apical site
What does it mean to accommodate interproximal wear
Mesial drift by occlusal forces and ligament contraction as well as pressures of cheeks/tongue
Why is tooth growth said to occur earlier in girls than boys
Related to burst of condylar growth that separates jaws and teeth
Apices of teeth move 2-3mm away from IDC
What are 7 affects of tooth wear
Reduction in anatomical/clinical crown height
Over closure
Reduction in vertical facial height
Denture difficulties
Mesial/distal wearing continuously
Increase in contact point
Reduction in length of arch
What is a factor of mesial drift of teeth
Impaction of 3rd molar arch unable to accommodate all teeth
If a tooth is lost
Osteoblastic/osteoclastic
What are 4 hypotheses to mesial drift of teeth
Mesial inclination of teeth produces resultant force during biting that favours mesial drift
Actions of certain jaw muscles, particularly Buccinator ‘propel’ teeth forwards
Bone deposited preferentially on distal surface of sockets pushes teeth mesially
Contraction of gingival connective tissues (especially transseptal collagen fibres in gingiva) brings about mesial drift
What does periodontal disease cause teeth to move
Buccal flaring of anterior teeth
Creation of median diastema
Apical movement of fulcrum point
Loss of PDL
Loss of supporting bone - resorption
What is ankylosis
Direct union of tooth to bone
What is extrusion
When a tooth is missing opposing tooth will move in an axial direction towards edentulous space eruptive force
More common with missing lower teeth
What is a result of mesial inclination of most teeth
Dentoalveolar compensation when teeth erupt vertically they encounter an opposing force equal to eruptive force to move them forward elongating dentoalveolar process
What do transseptal fibres do
Run between adjacent teeth across alveolar process draw neighbouring teeth together and maintain them in contact
What does soft tissue pressure influence
Tooth position as teeth will still drift mesial even without soft tissue pressure
What was the Dahl principle designed to create
Anterior space by separating posterior teeth through an anterior bite plane for 4-6 months
A combination of posterior passive eruption and anterior intrusion created the space leads to re establishment of posterior occlusion and anterior space
What is the anterior intrusion for the Dahl principle
Av = 1.05mm
What is the posterior eruption for the Dahl principle
Av = 1.47mm
What is the space creation in the Dahl principle
2mm
What is now done instead of the Dahl principle
Direct/indirect adhesive materials
For full mouth rehabilitation cases removable splints are often used to assess a patients ability to tolerate the planned change in their occlusion
