The Management of Occlusal Plane with Extra-Alveolar Miniscrews. Marcio Almeida
Extra-alveolar TADs
· Introduced by Chris Chang 2008
· Marcio Almeida Textbook on extra-alveolar miniscrews 2018
Total arch distalisation – Biomechanics using TADs Almeida 2019
· 2 key factors for total arch distalisation
o Height of hook (attachment to the archwire such as power arm)
o Height of the TAD
§ Can change incisal torque and occlusal plane rotation
What difference does the height make Kawamura 2021
· Changes to angle of force
o All angles clockwise rotation of occlusal plane
§ Intrusion of posterior teeth
§ Extrusion of anterior teeth
§ Loss of anterior torque
§ Clockwise rotation of maxilla of up to 11 degrees
Biomechanics of extra-oral Miniscrews
· Can distalise entire arch as segment
· Buccal shelf TADs distalisation (class 3)
§ Rotation counterclockwise Roberts 2015
· Can alter the rotation depending on the line of action direction in the mandible
o Above CR = counter clockwise rotation
o Below CR = clockwise rotationChae 2019
Example of biomechanics and line of action Class 3 with AOB
· IZC TAD: level with the arch = below CR = clockwise rotation of maxilla – aid AOB closure
· BS TAD 2 options
o Counterclockwise rotation desired = coil from TAD to archwire in 2-3 region
o Clockwise rotation desired = coil from TAD to long hook to archwire in 2-3 region
TADs Vs elastics in class 3 case
· No significant difference AP
· However biomechanically better vertical control due to counterclockwise control Nakamura 2017
Reference
Temporary Anchorage Devices in clinical orthodontics Jae Park
