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Growth Modulation by class 2 and class 3 orthopedics Hugo De Clerck AAO June. Episode 99

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Farooq Ahmed

Growth Modulation by class 2 and class 3 orthopedics Hugo De Clerck

 

Bone anchored Maxillary Protraction BAMP

Main reason for failure- surgical insertion Website www.lesschin.com, information for patients, orthodontists and surgeons

·      Effects

·      Protraction of the maxilla 5.2mm, when compared to PFM 2.3mm Cevidanes 2010, 5.8mm BAMP Vs 4.9mm Einagar 2016

·      Maxillary protraction: Zygomatico-frontal and zygomatico-termporal most effected, not the larger zygomatico-maxillary suture

 

Maxillary  / Mandibular rotation

·      Herbst: Posterior rotation of the maxilla (clockwise rotation) as molars intrude Pancherz 2002

·      BAMP / PFM anterior rotation, Upper molar moves downwards

o   PFM  posterior rotation mandible = increase in LAFH

·      BAMP

o   Line of action above condyle = anterior rotation of mandible lnagar 2016

 

Condyle changes

·      Class 2 condyle grows forwards, class 3 grows backwards

·      BAMP: condyle moves forwards

·      Herbst: condyle moves backwards

o   BAMP -= Posterior displacement of the condyle

§  Tension anterior, compression posterior

§  =Resorption posterior condyle, deposition anterior = displacement of condyle forwards

·      Herbst condyle is pulled forward

o   Resorption anterior, apposition nposterior

o   Condyle develops backwards

 

 

Gonial angle Enlow

·      Gonial angle remodelling linked to AP and vertical growth

·      Opening of the gonial angle in class 3

·      Closing of gonial angle in class 2 Jacob 2013

·      Gonial angle is the determinant of AP growth

·      BAMP = closure of Gonial Angle

 

 

Time line for class 3 orthopedics

 

Gonial angle changes during 11-13 years of age

Modelling changes can go on much longer

 

Strain growth of the mandible

BAMP closing of the gonial angle 4 degrees

 

Elastic force of class 3 elastics

·      Extrude upper molar

·      Extrusion of anterior teeth

·      Reduce gonial angle 4 degrees

·      Direction of condylar growth due to changes of the closing of the condyle

 

Class 2

Can the gonial angle be opened

·      Systematic review, inconclusive regarding mandibular growth

·      Non-systematic review De Clerck

o   Skeletal Go +0.05

o   Dental Li 10, Ui -4

·      Mandibular changes in Herbst Vs control  Souki 2017

o   Proclination of lower icnisors

o   Herbst condyle growth similar to class 3 growth = backwards

 

How does growth occur at the condyle

·      No change at the condyle head, but at the condylar neck through tension of the nec

 

 

 

 

 

 

 

 

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