Class 2 Biomechanics with Aligners. Episode 151. July 6th 2022

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Farooq Ahmed


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Join me for a summary of Dr Bing Fang’s lecture entitled: Biomechanical Research and clinical application of orthopaedic Treatment on Adolescent mandibular retrognathia. It was part of the first International Orthodontic Foundation online symposium, with Ravi Nanda

Pathogenesis = treatment

  • Retrognathic mandible average maxilla = functional appliance
  • Prognathic maxilla = extractions
    • If extraction and retrognathic maxilla = bimax retrusive appearance at the end

Intrusion with aligners

Clinical risk of anterior intrusion, can cause retroclination / proclination. 

  • Plan with assessing lower incisor inclination relative to skeletal structure from a cephalogram
  • To figure out this problem they designed a finite element study to figure out what happens for different lower incisor inclinations
  • If the IMPA angle  exceeded  100 the intrusive force will be in front of CR resulting in a moment causing lingual root torque and buccal crown torque
  • If the IMPA angle  less than  100 the intrusive force will be behind the CR resulting in a moment causing buccal root torque and lingual crown torque
  • Plan intrusion: 
    • Proclined teeth: intrusion and retraction at the same time with lingual crown torque
    • Retroclined teeth: Intrusion, with labial crown torque

Advanced Mandibular Spring AMS with aligner

  • Telescopic arm with spring.
  • Distalization of posterior and no movement in the anterior along with anterior bit turbos 
  • Class II elastics are used day time, appliance at night
  • Inserts into connectors which are imbedded into the aligner
  • How does it work
    • Finite model analysis, favourable for advancing the mandible – PDL even stress, promote mandibular growth, stress on condylar anterior aspect and posterior glenoid fossa
#alignerorthodontics #class2 #Bingfang #farooqahmed
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