Orthodontics - Physiology of Tooth Movement Flashcards
name the types of tooth movements. (2)
physiological:
eruption
mesial drift
orthodontic
name the 2 subgroups of physiological tooth movement.
tooth eruption
mesial drift
list the types of physiological tooth eruption movements. (4)
pre-eruptive
intra-osseous
mucosal
post occlusal
describe when pre-eruptive movement occurs.
Starts when crown is forming, ends when crown is complete and root starts to form
describe how quickly intraosseous movement occurs.
As soon as roots start to develop the tooth moves 1mm every 3 months
describe how quickly mucosal movement occurs.
just reaches the mucosa and it come through really fast 1-2mm per month
describe when post occlusal movement occurs, how fast is this?
Once tooth hits something hard i.e. the opposing tooth, the PDL becomes establish and there are very slow movements
describe the suggested mechanism of tooth eruption. (3)
- Root elongation and pressure around the apex from secretions
- Alveolar bone remodelling and the action of the dental follicle
- Reorganisation of the PDL membrane fibres and the role of fibroblasts
name the important factors in the eruption process. (3)
the dental follicle
apical blood flow
genetic factors i.e parathyroid receptor gene
how do you analyse ectopic canines on a radiograph?
- Height
- Closeness to the midline/how much is it overlapping the adjacent tooth
- Angle : bad prognosis = > 30 degrees or horizontal
what angle of an ectopic canine has poor prognosis?
> 30 degrees
horizontal
what structure allows a tooth to move? (1)
a PDL
name the mechanism responsible for orthodontic tooth movement?
Mechano-chemical pressure
describe the Mechano-chemical pressure mechanism of orthodontic tooth movement. (5)
- Mechanical stress applied to the tooth there are areas compression and tension on the tooth
- Neuropeptides are released from nerve endings
- Neuropeptides stimulate fibroblasts, endothelial cells and alveolar bone.
- Fibroblasts communicate with osteoclasts and osteoblasts
- The activation of the osteoblasts and osteoclasts = alveolar bone and PDL remodelling
where does resorption take place in tooth movement?
in areas of compression - in front of the tooth
where does deposition take place in tooth movement?
in areas of tension - distal aspect of a tooth moving forward
name the types of tooth movements that we can achieve. (6)
- Tipping - URAS = 35-60g
- Bodily movements – root moved with the crown 150-200g
- Intrusion = 10-20g
- Extrusion = 35-60g
- Rotation = 35-60g
- Torque = 50-100g
what movement do URA’s use?
tipping
how much pressure is required for tipping movements?
35 – 60g
how much pressure is required for bodily movements?
150 - 200g
describe bodily movements.
- Coordinated bone modelling and remodelling: allows resorption on one side and deposition on the other
how much pressure is required for intrusion?
10-20g
how much pressure is required for extrusion?
35-60g
how much pressure is required for rotation?
35-60g
how much pressure is required for apical torque?
50 – 100g
name the histological changes occur in the application of light orthodontic forces?
Frontal Resorption
name the histological change that occurs in the application of moderate orthodontic forces? (1)
undermining resorbtion
what happens if excessive orthodontic force is applied? (5)
- Necrosis
- Undermining resorption
- Resorption of root surfaces
- Pain
- Permanent change
what factors affect the response to orthodontic forces?
- Magnitude (the force applied)
- Duration of wear
- Age
- Anatomy
what anatomical features influence the response to orthodontic treatment? (3)
• Volume of bone
- Alveolar neck (from lost teeth) composed of 2 dense cortical plates: takes a long time to move tooth through this bone.
- Effects of the tongue – acts against the appliances
- Digit habits
what are the deleterious effects of orthodontics? (5)
- Pain and mobility
- Pulpal changes
- Root resorption
- Loss of alveolar bone support
- Relapse
