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Early treatment of class III malocclusion with TADs Peter Ngan. Episode 31. IOC 2020

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Farooq Ahmed

Ideal case for interceptive class III correction

  • Case type: low angle functional shift
  • Type of treatment: orthopaedic treatment

 

Success rate

Systematic review of class 3 interceptive treatment with protraction facemask : Woon 2017

  • Overjet improves: 2.5mm
  • AOB improves 3.9o
  • But short term improvement

 

Long term study

  • 5 year follow up systematic review: 75% stability with protraction facemask, chincup and FR3 Toffol 2008
  • 10 year follow up: 81% stability with chincup and expansion Palma 2015

 

Cause of relapse

  • Reduced maxillary growth (2mm) & excessive mandibular growth (4mm)

 

Expansion with protraction facemask – to loosen the Maxilla to facilitate advancement

  • Alt-RAMEC protocol: Repeated expansion and constriction of the maxilla
  • Systematic review favouring Alt-RAMEC Vs conventional RME
    • SNA 1.2 greater with Alt-RAMEC
    •  

Ngan protocol for PFM and Alt-RAMEC

  • Alt-Ramec: 2 week expansion, then alternate constriction and expansion for 7 weeks,
  • PFM at night, with 30 o to the occlusal plane
  • Lower 2 x 4 fixed for alignment and class 3 elastics 018SS
  • Day time class 3 elastics
  • 9-12 months of PFM

 

Skeletal anchorage and class III correction: Bone anchored maxillary protraction (BAMP)

  • Can be used in patients older than PFM patients
  • Systematic review: less chance of skeletal relapse with BAMP Guzman – Barrera 2017

 

Decision making after 11-14

  • Skeletal expansion with TAD supported expansion
    • Device: Maxillary-skeletal expansion device
    • 2mm + 12mm length: aiming for bicortical anchorage
    • PFM 11 months
    • Retention: essix with class 3 elastics in retainers- cut out lower VFR and button upper molars – maintain maxillary stimulation
    • Seminar in Orthodontics: 2020 Ngan

OVERALL SUCCESS OF INTERCEPTIVE ORTHOPAEDIC TREATMENT IN CLASS 3 CASES IS 70%, IF AETIOLOGY IS MAXILLARY DEFICIENCY

 

 

References

Ngan P, Musich D. Stability and relapse of Class III treatment. Stability, Retention and Relapse in Orthodontics. USA: Quintessence Publishing; 2017. p. 93-124.

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