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
