Padhraig takes us through the evidence of retention, his hierarchy of stability and his technique of placing a bonded retainer
Classic paper of Little 1999
- After treatment
- Post treatment relapse – greater in non-extraction cases
- Maturation changes
- Little recommended indefinite retention
Overbite stability
- Schutz-Fransson 2006 – less than 1mm of change long term
- Padhraig argued vertical changes are due to loss of alignment of the lower anterior teeth, slipped contact points, lingually displaced incisor, free to overerupt.
Interdigitation
- Pancherz 1982 – theorised stability with interdigitation
- Oliver 2020 – only 10% of patients had relapse
Retention wear
- Part time wear as effective as full time – possibly advantageous as less wear
Type of appliance
- Littlewood Cochrane RV supports VFR over Hawley, but only assessed over 6 months
Retention regime long term
- Al Moghrabi 4 year follow up study
- Fixed Vs VFR
- Irregularity fixed 0.8mm, VFR 2.4mm statistically significant
- Wear – usually 5 hours less then prescribed
- Long term wear: At 2 years less than 33% complaint
Periodontal outcomes
- No difference in fixed Vs VFRs
Compliance app
- No difference using App Vs no App – increase in 1 hour of wear.
- When recommended full time wear: average patient 6-7 hours
Compliance has not been tested for the average patient – 60-70 years.
Complications
- VFRs – reduce fracture by increasing to 0.9-1.5mm thick retainer
- Fixed retainer – 30% breakage in 3 years
- Tip to reduce fractures of bonded retainers change to flex tech
- Twist flex: rigid wire – unlikely to fracture but force can propagates and creates tooth movement / fracture.
- Flex tech: Less rigid, wont generate force, but can fracture. Padhraig places a large composite pad to reduce wire exposure.
- Composite broad and shallow
- Tip to reduce fractures of bonded retainers change to flex tech
Placement of retainer
- Etch bond
- Flowable on central
- Use bond brush to adapt flex tech – place more composite
- Continue from central outwards
- Transbond flowable composite
Flemings hierarchy of stability
- AP correction stable
- Vertical: deep bite some relapse but minimal
- Transverse: relapse does occur, require use of more rigid retention
- Vertical: AOB biggest risk fo relapse: require active retention
Conclusion
Padhraig Fleming has increased the number of bonded retainers, and reduced the reliance of VFRs, focusing on interdigitation.