Biomechanics of the Invisalign system 2021 John Morton. Episode 83. June 2nd 2021

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Hosted by
Farooq Ahmed


Join me as I summaries John Morton’s lecture from this year’s Invisalign Aligner Summit


John Morton, director of research and technology for Align describes G8 with invisalign




How to aligners move

  • Force driven system: Shape of the appliances derived from the force desired to be delivered
  • Displacement driven system – Shape of the appliance is the location of the tooth in the desired position, no concept of force being applied



Invisalign system

  • Smartforce features
    • Control the position of the crown relative to the roots
  • SmartTrack material
    • Control movement of the teeth applying the force
  • Smartstage technology
    • Progression of tooth movements
    • Coordination of arches
    • Which tooth moves 1st etc – G8


G8 change in contour of the aligner and the tooth surface


  • Smartforce feature: – Optimised attachment
    • Temporary change to shape of the tooth with composite
    • Aligner to contact tooth surface to produce a force in the direction of desired movement
    • Large flat surface Vs conventional attachment (sloped surface)
      • Reliable that aligner will contact the surface – we can measure it
        • Where to put attachment
        • What is the direction of the force
        • What is the magnitude (measured by being perpendicular)


  • Mismatch of tooth shape and aligner formation
    • Small mismatch = flex of aligner
    • Large mismatch = bowing of aligner labially = large force




  • Improve efficiency
  • Smartforce activation
    • Changes contact of the aligner with tooth surface
      • Control contact points = control force, magnitude and direction
      • Examples
        • Intrusion
        • Expansion



Intrusion for deep bite with G8

  • 2N force on each tooth to predictably deliver intrusion for deep bites


  • Displacement driven system = – each tooth receives the same activation, however different forces are generated
  • G8 delivers different activation / mismatch tooth Vs aligner = same force levels on teeth being intruded


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