Retention And Stability Flashcards
What malocclusions are more likely to relapse?
- spacing/
- rotations
- deep overbite
- arch form changes e.g expansion
- altered LLS position
- periodontal involved teeth
What are the 3 divisions of relapse?
- physiological recovery - return to original malocclusion
- unfavourable growth
- ‘true relapse’ - due to treatment choices e.g. expanding lower inter canine width
How long does it take for periodontal fibres to remodel?
1-2 months
How long does it take for supra-crestal gingival fibres to remodel?
6 months
How long does it take for free gingival fibres to remodel?
12 months
How long does it take for osteoid bone to remodel?
3 months
What are the advantages of vacuum formed retainers?
Good aesthetics Cheap and easy to construct Superior retention of lower incisors Preferred by patients Less affect on speech
What are the disadvantages of vacuum formed retainers?
Less effective at maintaining expansion
Less occlusal/posterior settling
Risk of decalcification/caries of worn when eating and drinking
What are the advantages of hawley retainers?
Simple to construct Robust Easy to add a Pontic tooth Can be worn when eating Allows posterior settling Rigid to maintain transverse corrections Labial bow - simple incisor movements
What are the disadvantages of hawley retainers?
Difficult to tolerate - in particular the lower
Expensive compared to VFR
Takes time to make
Effects speech more than VFR
What are the advantages of fixed retainers?
Less demand for patient compliance
Discreet
What are disadvantages of fixed retainers?
High failure rate
OH - difficult
Long term maintained
Patient may not know it is broken - risk of caries and tooth movement
What specific problems are fixed retainers used for?
Rotations Diastema Spacing Displaced teeth Periodontal issues
What are vacuum formed retainers Made out of?
Polyvinyl chloride sheets
What are relapse causes/factors?
- pro-facial soft tissues
- post treatment facial growth
- occlusion
- age related changes
What is retention?
Holding of teeth following orthodontic treatment, in treated position for a period of time necessary for maintaining result
What is relapse?
- the return, following correction, of the original features of malocclusion
- unfavourable changes, from the final tooth positions achieved at the end of orthodontic treatment
How can relapse be minimised?
- consider extraction of rotated or displaced teeth
- maintain arch form and inter canine width
- minimal alteration of lower labial segment
- consider IPR
What is dual retention?
Fixed retainers used with removable retainers
What are the potential causes of late lower incisors crowding in an untreated patient?
- inter canine width reduces
- eruption of 3rd molars
- growth in lower jaw
What is the stability of treating a patient with Bimaxillary proclination?
Variable
• retroclining the labial segment causes infringement on the tongue space
• space will want to re open if they were present pre treatment
