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Premolar extraction protocols Part 2 What you may not know…
Premolar extraction protocols Part 1 What you may not know…
IPR accuracy exposed! What this study reveals may surprise you
Does Trimline matter in Aligners?
Open bite + Aligners = Gold standard?
Do you know how to do IPR safely?
How well do aligners perform in closing premolar extraction spaces?
Extrusion movements with Clear Aligners
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Gum recession during Aligner treatment - What should you do?
The importance of attachments during expansion
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Understanding Aligner Limitations in Arch Expansion 📚🔍
Ghost IPR in Clear Aligners
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Difficult Movements with Clear Aligners

Extrusion movements with Clear Aligners

How to predictably extrude with clear aligners?

Incisor Extrusion with Clear Aligners: Finite Element Analysis Insights

Study: Appl. Sci. 2021, 11(3), 1167.
Authors: Rossini G, Modica S, Parrini S, Deregibus A, Castroflorio T (University of Turin, Italy*)

Key Findings

  1. Challenges in Pure Extrusion:
    Lateral incisor extrusion     is particularly difficult with aligners alone.
    Pure extrusion requires auxiliary techniques (e.g., bootstrap, procline-retract protocol).

  2. Optimal Attachment Strategies:
    Best Results:
    ATT3-7     (attachments from second molar to canine) + horizontal attachments on incisors (buccal/palatal).
    Stress Distribution: This combination improved force application and reduced uneven pressure.

  3. Anchorage Preservation:
    Posterior attachments     are critical to prevent anchorage loss during incisor extrusion.

Author Recommendations

  • For Effective Extrusion:
    Always use horizontal attachments on all four incisors.
    Add posterior attachments (molars/canines) to maintain anchorage.

  • Clinical Note:
    Relative extrusion     (e.g., intruding adjacent teeth) is easier than pure extrusion.

Study Methodology (FEA Simulations)

Tested 6 configurations:

  1. No attachments.

  2. Horizontal attachments (incisors only).

  3. ATT3-7 (molar to canine).

  4. ATT3-7 + optimized extrusion attachments (incisors).

  5. ATT3-7 + buccal horizontal attachments (incisors).

  6. ATT3-7 + palatal horizontal attachments (incisors).

Result: Configurations 5/6 (horizontal incisor attachments + posterior anchorage) performed best.

Clear Aligner Academy Tips

Takeaway

  • Attachments are non-negotiable for predictable incisor extrusion.

  • Posterior anchorage is key to avoid unwanted tooth movement.

  • Hybrid approaches (aligners + auxiliaries) may be needed for pure extrusion cases.

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