Aligners: do patients wear them and do attachments really work?

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Hosted by
Farooq Ahmed


Aligners: do patients wear them and do attachments really work?

Tommaso Castroflorio

Join me for a summary of Tommaso’s lecture on aligner treatment, exploring questions on the use of aligners. Tommaso described how compliant patients are with the use of aligners, who is more likely to wear aligners well and methods to increase compliance. He critically reviewed the use of attachments, and revealed aligner deformation and staging as key areas of treatment. This podcast is a summary of the WFO online webinar from November patient compliance, biomechanics , rotation, distalisation and intrusion

Patient Compliance

Sample of over 200 patients treated with aligners under remote monitoring, Thirumoorthy 2021:

  • 36% of the sample was fully compliant
  • 25% has poor compliance
  • 1st time Ortho patients are more compliant
  • Conclusion: early detect non compliant patients with remote monitoring 

Patient factors which vary compliance of removable appliances Fleming 2019

The study came with some recommendations:

  1. Effective communication with our patients, with visual aid, pictures or movies.
  2. Using of tracking sensor included in the device
  3. Using some reminding tools – remote monitoring

Biomechanics and material properties.

The mean accuracy of Invisalign for all tooth movements was 50% Haouili 2019 

  • However 74% of the randomly chosen patients passed the ABO score, similar to Nikhilesh Vaid’s unpublished stufy at 78%
  • Reason why he and a lot of colleagues are still using aligners despite the 50% of accuracy.

Factors which influence accuracy.


  • In his experience: Attachments are required to maximize the total aligner interaction.
  • BUT evidence the moment are not usually provided by the attachment 
    • When the moment of couple does exist on the attachment itself multiple interferences exist which will degrade the intended force.
  • Example extractions and aligners:. 
    • Posterior and anterior anchorage in extraction cases using aligners Zhu 2023.
    • Squeezing the teeth, particularly:
    • Premolar extraction space closure cause mesial tipping, lingual tipping and intrusion of mandibular molars.

.Overcorrect via:

  • Vertical: extruding the middle of the dental arch and intruding the ends
  • Attachments to control the vertical, long vertical anterior, horizontal posterior
  • Class II elastic traction resulted in more mesial tipping and less intrusion of mandibular molars
  • For each aligner stage (0.25mm movement), anchorage preparation of 1.7 degree could be designed for bodily molar mesial movement with distal and lingual cutouts. And 2 degrees for maximum anchorage patients
  • “We were focused only on attachments, aligners are elastics and they are going to deform and that can provoke so me undesired movements that you need to control.


Difficult canines as linear force on round object

  • Paper to be published by Tommaso: 
    • Add attachment including adjacent teeth 
    • Reduce to one degree of rotation per aligner (1.2 too much)
    • Rotation alone with no other movements at the same time.
  • Overcorrection Castroflorio 2023
    • Maxillary canines 0.4 degree of overcorrection for every 1 degree of planned movement.
    • Mandibular canine 0.3 degree of overcorrection for every 1 degree planned movement.
    • 14 day changes increases accuracy by 12% for Lower canines and premolars torque control and lower molar rotation

Distalisation class 2

Aligner cases treatment = poor outcomes and did not pass ABO Patterson 2021, however Aligners are just an appliance, its delivery is through planning 

  • When aligners distalise = lose posterior vertical anchorage and anterior anchorage.
  • Correct via use of Class 2 elastics to control anterior anchorage and control vertical anchorage 
  • Aligners effective in distilling maxillary molars in non growing patients without significant vertical and mesio-distal tipping movement. Ravera 2016
  • Attachments canine to molars = 
    • Reduce tipping.
    • Control vertical.
    • More stabilization.
  • Up to 2-3 mm of distalisation possible.

Incisors intrusion

impossible to achieve pure intrusion, part of the deep bite correction is by proclination.

1 stage Vs 2 stage intrusion lower arch

  • If canine intrusion 1st = 0.2mm effective intrusion Yang Liu 2018
  • If all 3-3 intrusion = proclination only

Upper incisor intrusion:

  • Colum angle = difficult to apply true intrusive force
  • Need attachment palatal surface to control the intrusion

The  plastic material is pre-activated not only on the active surfaces of the attachments, but also in other areas in order to better control your total teeth movement.


  • We need to consider the lines of forces and aligner deformation not only on the attachments
  • Any malocclusion that can be corrected by tipping has better predictability 
  • Add less activation Per aligner (to help flattening the steep decline in force over time and create consistent and continuous force system)
  • Attachment driven mechanics are not always effective, aligner Activation is more effective
  • Graphy is the trending technology in aligner activation

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