Retention and stability Flashcards
Define retention
Maintenance of intra-arch relationship (alignments) and inter-arch relationships (static and dynamic occlusion)
Define relapse
Tendency for a treated malocclusion to return to the original features of occlusion (BSI)
What else can be considered relapse?
Any change to the teeth that occurs after treatment e.g. late lower incisor crowding
What is the importance of retention?
Without retention, the teeth will return back to normal
What are the aetiological factors for relapse?
Gingival and periodontal factors Post tx growth and maturation Ageing Soft tissue factors Occlusal factors
What are the gingival/periodontal factors associated with relapse?
If the fibres have not remodelled, there is tendency for them to pull the tooth back to the original position
How long does it take for gingival/perio fibres to reorganise post op?
4-6 months
Some may take 8 months
What type of post treatment growth can cause relapse?
- Late mandibular growth can cause late lower incisor crowding
- Any unfavourable growth with class II or III cases
What changes occur as you age and how can this cause relapse?
Reduction in intercanine width and arch length - thus causing tertiary crowding
What soft tissue factors can increase risk of relapse
- Tongue pushing forward
- Incompetent lips post op
Examples of occlusal factors that can reduce the risk of relapse
- Good interdigitation
- Centroid position and an occlusal stop (in overbite correction)
- For anterior XB correction adequate overbite is required
Importance of soft tissues in correction of class II div 1
The upper incisors ideally should be in control of the lips post op and there should be competence to allow stable overjet reduction
Why are changes to the inclination of the LLS prone to relapse?
The further the teeth lie from the zone of balance, the more unstable the position is
Why are space closures and corrected rotations prone to relapse
Transseptal fibres take long to reorganise and they may pull the teeth back into the original position
List areas prone to relapse post ortho treatment
- close spaces/diastemas
- correction of severe rotations
- Excessive lower incisor proclination or retroclination
- Reduced OJ with incompetent lips
- combined perio and ortho
