Week 2 Abdalla: Relapse and retention Flashcards
What is retention and relapse?
- Retention: holding teeth following ortho tx in treated position for period of of time necessary to hold result
- Relapse: tendency to return to pre-treatment positions
Why is attached gingiva problematic for ortho?
Gingiva is firmly attached to underlying bone and cementum by connective tissue and is immobile. Significant tooth movements stretch collagen and they have tendency to recoil.
How long does it take for gingival and periodontal tissues to re-organise?
- Periodontal fibres: 3-4 months
- Gingival fibres: 4-6 months
- Trans-septal fibres: 12 months
What is circumferential supracrestal fiberotomy?
Cut fibres around gingival margin with scalpel around each tooth. Effective tx to prevent teeth rotating back to their original position after successful orthodontic care
What factors can interfere with retention following ortho?
- Periodontal and gingival anatomy
- Soft tissues
- Occlusal balance
- Growth and development
Why is soft tissue and occlusal balance important to prevent relapse?
Want teeth in neutral area- equal force exerted by tongue on one side and cheek on other side
Why is it important to eliminate lip trap?
If you don’t eliminate lip trap after treatment, tooth position will relapse
When can you not extrude incisors to correct open bite?
If they are already extruded (see lat ceph). Orthognathic surgery may be required.
What ortho movements are least stable?
- Vertical changes (anterior open bite)
- Transverse change
Why do people get crowding of incisors in lower arch as they age?
Intercanine width decreases 1.2mm between 13-45 years
When does mx growth terminate in girls vs boys?
Girls: 15
Boys 17
When does md growth terminate in girls vs boys?
Girls: 17
Boys: 19
In what cases is md growth a concern for relapse?
If pt has open bite (teeth will continue to move apart as md grows)
What are the pros/cons of removable retainers?
- Worn on part time basis
- Removable for cleaning
- Rely on compliance
- More intrusive
What are pros and cons of fixed retainers?
- Don’t rely on compliance
- More difficult to clean
What are acrylic retainers with labial bow?
- Robust- won’t get damaged during eating
- Allow posterior occlusal settling
- Anterior bite plane can be incorporated to help retain corrected deep bites
- Not very well tolerated (can be seen easily)
- E.g. Hawley, Begg retainer
What are characteristics of bonded/fixed retainers?
- Discreet
- Don’t rely on compliance
- Long term failure rate high
- Can become active and cause tooth movements
- Care with bonded upper retainers to minimise occlusal contacts
- Impede OH
