17 - Histology of Tooth Movement, Retention and Stability Flashcards
What is orthodontic tooth movement based on:
Principle that application of a light, continuous force will bring about tooth movement
Histology shows a tooth moves through bone due to changes in the PDL, brought about by the orthodontic force.
PDL
What is the PDL?
3 things PDL composed of:
Identify
Preassure tension hypothesis
What odes ortho force result in:
First bone forms is called woven bone
Later matures to lamella bone
Cell level - leads to acute inflammation hence pt feels pain, then follow by chronic inflam process
Ideal orthodontic force
1- heavy or light
2- how long should force be applied - hours and how long long term?
4- rate of tooth movement :
Excessive orthodontic force leads to: (4)
Types of tooth movement
3 main types:
Other types:
How do each of these movements look
Retention
Define retention
Define relapse
When is retention advisable?
What phase of treatment is retention?
(Except in correction of anterior crossbite treated in mixed dentition - Interceptive treatment. If adequate overbite then don’t need retainer)
Retention
4 reasons for retention
Mandibular growth - mandible grows 2-3 years after maxillary growth has stopped - can lead to post treatment relapse esp in skeletal III pts
Soft tissues
What is soft tissue balance?
Which occlusion is this important in?
For correction of patients with increased overjet - class 2 div 1 - for long term stability of the corrected overjet, lower lip should cover the Incisal third of the upper incisors at rest at the end of treatment - achieved lip competency
Remodelling of supporting structures - Reorganisation of the PDL/gingival fibres: (4)
Future growth - important in which cases
Important in skeletal 2 or 3 cases
Retainers
1- what are retainers
2- Types of retainers:
Hawley retainer
1- design
2- disadvantage
3- adv
Not used as much anymore
Adv = allows for post treatment occlusal settling
Vacuum formed retainer (VFR)
1- Made from?
2- coverage of?
3- advantages
Most popular design of retainer
Fixed retainer
Advantages
Disadvantages
Does it have perio effects?
What can it interfere with?
Indications (3)
Retention regimes
How often should retainers be worn?
How long after treatment?
Fixed retainers?
Specific stability problems - where you might consider fixed retention in addition to removable
List 4:
Adjunctive procedures
For rotations what can we do
What is this?
Which dentition is this?
Treatment?
1- anterior crossbite
2- Patient in mixed dentition
3- upper removable appliance in the mixed dentition - Interceptive treatment. Can use Z spring on back of incisors that’s in crossbite to procline the tooth over the bite - (dont need retainer after this)
What’s this?
Hawley retainer with a modification - contains Pontics
Eg for pt with Hypodontia - cant do RBB straight away, so provide retainer with pontics to allow settling of gingiva before prosthesis
What’s this?
Hawley retainer
There’s acrylic on the bow- this is called acrylated labial bow - used when want more hold of the incisors eg when lots of rotations at the front of the mouth
Would probably use VFR now instead of this - more control of the incisors
What’s this?
Hawley retainer
There’s acrylic on the bow- this is called acrylated labial bow - used when want more hold of the incisors eg when lots of rotations at the front of the mouth
Would probably use VFR now instead of this - more control of the incisors
What’s this?
