Physiology of Tooth Movement Flashcards by Roisin Mousa

What are the types of tooth movement

physiological

orthodontic

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What are the physiological tooth movements

tooth eruption

mesial drift

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How is orthodontic movement done

through externally generated forces

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What are the different movements in tooth eruption

pre-eruptive tooth movement
intra-osseous eruption 
mucosal penetration
pre-occlusal eruption 
post-occlusal eruption

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What is the speed of pre-eruptive tooth movement

small and random

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What is the speed of intra-osseous eruption

occurs after crown forms
slow
1mm takes around 3-24 months

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What is the speed of mucosal penetration

fast

1mm takes about 2 weeks

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What is the speed of pre occlusal eruption

slow

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What is the speed of post occlusal eruption

very slow

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What are the different tooth eruption theories

pulpal pressure
pulpal growth
fibroblast traction
blood vessel thrust

main 3:
root elongation
alveolar bone remodel
PDL formation

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What is the process of tooth eruption

the dental follicle is the mediator for bone resorption
the bone and the deciduous root has to be resorbed for the tooth to come through
apical blood flow is important
collagen fibre cross linking is only important after eruption
parathyroid hormone receptor gene (PTHR1 and PPE)

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How can orthodontics utilize tooth eruption

to minimize impact of a developing malocclusion

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How can an ectopic upper permanent canine be treated

by interceptive extraction of the deciduous canine (10-13yrs)

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How can permanent teeth be encouraged to erupt

if deciduous tooth is extracted at correct stage

1/3-2/3 of root development

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What is the physiological basis of orthodontics

if an external force is applied to a tooth, the tooth will move as the bone around it remodels

if a tooth has no PLD or it is ankylosed it will not move

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What is the bony remodeling seen in orthodontics mediated by

periodontal ligament

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Why does bone resorb and cementum not in tooth movement

cementum is more resistant to resorption than bone

although some degree of root resorption after ortho should be expected

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What does an orthodontist do

manages the growth and development of the teeth face and jaws

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What are the 3 theories for orthodontic tooth movement

differential pressure theory
piezo electric theory
mechano-chemical theory

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What is the differential pressure theory

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The side of pressure’s PDL is under tension while the other is compressed
on the tension side there is bone deposition and the compression side there is bone resorption

What is the piezoelectric pressure theory

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Piezoelectric currents are generated when crystalline structures, such as bone, are deformed

these currents have been suggested as the prime mechanism by which tooth movement is modulated

What is the mechano-chemical pressure theory

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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 remodeling –> tooth movement

What are the types of ortho appliances

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URA (removable)
functionals
fixed

What are upper removable appliances

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made of acrylic and wire

can tip teeth

What is a functional appliance

growth modification device twin block good for class 2 division 1

What are the types of tooth movement

``` tipping bodily movement intrusion extrusion rotation torque ```

What is the ideal force for tipping

35-60 grams

What is tipping

the centre of rotation is around the middle of the tooth and as it tips it moves up

How do functional appliances work

mandible is postured away from usual rest position facial musculature is stretched which generates forces transmitted to the teeth and alveolus may be effect on facial growth

What is the mode of action of functionals

skeletal change (30%), growth of mandible, restraint of maxilla dent-alveolar change (70%) retroclination of upper teeth, proclamation of lower teeth mesial migration of the lower teeth distal migration of the upper teeth combination of the above achieves class I

What is the ideal force of bodily movement

150-200 grams

What is bodily movement

there is coordinated bone remodeling response leading and trailing the moving tooth this mechanism allows a tooth to move relative to basilar bone while maintaining a normal functional relationship with its periodontist

What is the ideal force for intrusion

10-20 grams

What is intrusion

pressure on supporting structures is evenly distributed and bone resorption is necessary, particularly at the apical area and at the alveolar crest

What is the ideal force for extrusion

35-60

What is extrusion

tension is induced in the supporting structures and bone deposition is necessary to maintain tooth support

What is the ideal force of rotation

35--60 g

How is rotation achieved

two forces going in opposite directions have stretched elastic module stretched elastic chain on other side

What is apical root torque

root uprighting

What is the ideal force for apical root torque

50-100g

What happens with light force

hyperemia within the PDl appearance of osteoclasts and osteoblasts resorption of lamina dura from the pressure side via osteoclasts apposition of osteoid on tension side via osteoblasts remodeling of socket in frontal resorption periodontal fibres reorganise gingival fibres appear not to become reorganized but remain distorted

What happens with moderate force

occlusion of vessels of PDL on pressure side hyperemia of vessels of PDL on tension side cell free areas on pressure side (called hyalinization) period of stasis increased endosteal vascularity (undermining resorption) relatively rapid movement of tooth with bone deposition on tension side - tooth may become slightly loose healing of PDL - reorganization and remodeling

What happens with excessive force

``` necrsos undermining resorption resorption of root surfaces pain permanent change ```

What is the histological effects of excessive force

extensive lateral root resorption (RR) and undermining resorption (UR), just to the left of an area of PDL necrosis (N) is associated with the lag phase of tooth movement

What are factors affecting the respone to ortho force

magnitude duration age anatomy

What anatomy can effect response to force

no bone - wasting/cleft | soft tissue mid palatal suture

What is the deleterious effects of ortho force

``` pain and mobility pulpal changes root resoprtion loss of alveolar bone support relapse ```

How much tooth movement per month is ideal

1mm

What is the treatment time for fixed appliances

24m

Physiology of Tooth Movement Flashcards

(49 cards)