Retention Flashcards
What are the four causes of relapse?
soft tissue
occlusal factors
facial growth
supporting tissues
What soft tissue factors influence stability?
teeth need to be in the neutral zone
Lips cheeks and tongue need to be in balance and during treatment this balance changes and thus need to establish new balance
What soft tissue factors influence stability in class 2/1?
lower lip in front of upper incisors following treatment
Severely incompetent lips at the start of treatment will mean unstable OJ reduction
What occlusal factors influence stabilty in class 2/1?
need an appprotate inter incisal angle of 135 degree and lower incsors must be 2-3mm anterior to the centrol of upper incisors
All cases need good intercuspation
What occlusal factor will influence stability in class 3?
adequate overbite
What feature may worsen with posterior growth oattern?
AOB
What malocclsuion worsens with anterior growth pattern?
class 3 and deep overbites
what percentage of people need re treatment within 10 year spost ortho?
70%
What are the components of the supporting tissues which influence stabilty?
bone
pdl
gingiva
How long does it take bone to remodel?
3 months
What happens to the pdl during treatment?
it is put under tension
What happens to the pdl following treatment?
it has a tendancy to want to spring back
How long does it take sharpey fibres to remodel?
1-2 months
Which fibres within the gingiva are present?
supra-crestal fibres
free gingival fibres
How long does it take supra crestal fibres to re model?
6 months
how long does it take free gingival fibres to remodel?
12 months
Which features of malocclusion are prone to relapse?
derotation
incisor crowding
periodontal disease
median diastemas
What can you do to th gingiva in rotations?
pericision
this is when you the supracrestal fibres
Why are incisor crowding prone to relpase?
narrow contact points
growth
eruption
What are the types of retainers?
fixed
removable
What are the types of removable appliaces are there?
hawley
VFR
Which removable appliances are better at preventing relaps in the lower arch?
VFR
What instuction do you give to people with VFR?
do not drink with them in
When would you not give a VFR?
people with poor OH as VFR engages into the gingival undercut and if pateint has gingitivits then cannot engage
What is relapse ?
The return following correction of features of the original malocclusion
What is stability?
The dentition existing in a state of equilibrium between the forces imparted by the soft tissues lips checks and tongue
What is retention?
Phase following active orthodontic treatment which is aimed at stabilisation of the achieved orthodontic correction
What are graduates of relapse related to?
The factors affecting stability
Which feature worsen with facial growth?
Class 3
AOB
Deep overbutes
Late incisor crowding
What must be some with class 3 to avoid relapse?
Over correct or treat later
What are the advantages and disadvantages of a removable retainer?
+Easier for OH
+Can be worn part time
-responsibility of the pt
What are the advantages and disadvantages of a fixed retainer?
+Patients do not need to remember to wear them
+Useful when results are unstable
- risk of debond and patient won’t know
- technique sensitive
Whh are fixed retainers advises?
Closure of spaced dentition eg median diastema
Rotations
Lower labial segment has had substantial movement
Combined perio and ortho
What are the types of fixed retainers?
Multistrand which are bonded to each tooth in labial segment
Rigid canine and canine retainers bonded only to canines ( tend to result in relapse of unrestrained teeth)
Reinforced fibres (tend for fracture)
What adjunctive techniques are there to preventing relapse?
- Pericison
2. Interproximal stripping
How does precision work?bhow how effective is it?
Cut the interdental and dento gingival fibres above the alveolar bone level
Used of de rotated teeth
Reduces relapse by 30%
How does interproximal stripping work?
Removal, of small amounts of enamel mesiodistal Distally to flatten contact points and increase stability
Not much evidence for this
What material are fixed retainers made from?
Stainless steel
Used to be from eligloy
