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Vertical Dimension And Facial Aesthetics Sylvain Chamberland. Episode 34. IOC 2020

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Hosted by
Farooq Ahmed

Long face syndrome Buschang 2011

  • Excessive anterior and posterior face height
  • Open bite
  • Increased lower facial height
  • Steeper mandibular plane
  • Larger gonial angle
  • Lower face height proportions, not 1/3 – 2/3 , closer to ¼ – ¾

 

Treatment options

  • Orthognathic surgery
  • Orthodontics with TAD intrusion

 

TAD mechanics

  • Maxilla: Modified TPA with mid palatal TAD – 1.8mm
  • Mandible: Between 6-7 and lingual arch – 1.2mm
  • Overall effect:
    • 2mm of improvement of overbite
    • Clockwise rotation of mandible
  • Segmental approach can help prevent extrusion of anterior teeth

 

Autorotation

  • Centre of rotation of mandible – below and behind condylion
  • 1mm posterior maxillary intrusion: Kim 2018
    • OB increase of 2.6mm
    • Decrease LAFH 1.8mm

 

Success

  • 60% achieved 2-4mm of intrusion
  • Post treatment relapse of 2-4 in 16% of cases Scheffier 2014

 

TAD positioning

  • Palatal TAD for intrusion
    • 8-9mm from contact point, 9mm+ = thin bone + close to sinus
    • Between first molar and 2nd premolar / bicuspid
    • Likely rolling in of the molars – use TPA / expansion archwire
  • Buccal TAD for intrusion
    • 5-8mm above crestal bone (above mucogingival junction)
    • Between first molar and 2nd premolar / bicuspid
    • Likely buccal flaring of molars – constrict archwire

 

Force for intrusion

  • 200g Vs 400g = no difference Aki 2020

 

 

Intrude anterior teeth

  • Distal to upper centrals
  • 6mm TADs
  • E links
  • 3-4mm of intrusion
  • force 100g
  • Possible external root resorption

 

Protocol

  • Segmental 7-4, 3-3
  • Buccal TAD maxilla between 5-6, and 2 x mid-palatal TADs with TPA
  • Buccal TAD mandible between 6-7
  • Elinks for intrusion force

 

Clear aligner therapy

  • Overall change in overbite 3mm
  • No change in vertical dimension
  • Mainly correct via extrusion of anterior teeth
    • Upper incisor extrusion 1.5mm Vs Upper molar intrusion 0.5mm Harris 2020
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