Orthodontic Retention Not Letting Go Padhraig Fleming. Episode 43. IOC 2020

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
  1. Post treatment relapse – greater in non-extraction cases
  2. 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

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

1. AP correction stable
2. Vertical: deep bite some relapse but minimal
3. Transverse: relapse does occur, require use of more rigid retention
4. 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.