Effect of Clear Aligner Attachment Size on Extrusion of Maxillary Lateral Incisors

June 5, 2026 updated by: Virginia Commonwealth University
Orthodontic treatment has been revolutionized by clear aligner therapy, offering patients a more esthetic and comfortable alternative to traditional braces. In 1999, Align Technology introduced Invisalign. As Invisalign has increased in popularity and demand over the past two decades, clinical trials have shed light on the efficacy of Invisalign treatment. there have been changes in the Invisalign protocol such as introduction of SmartForce features in 2008, such as optimized attachments as well as the implementation of SmartTrack aligner material in 2011. Compared to conventional fixed orthodontic appliances, Invisalign cannot be adjusted on a visit-to visit basis. If ideal tooth movement has not been achieved after completion of the first sequence of aligners, additional trays, known as refinement trays, are required.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

There are various expert theories regarding the most effective methods of extrusion and multiple studies performed in vitro to evaluate the efficacy of different attachment types on the extrusion of lateral incisors, however only one in vivo clinical trial exists. There is a need for more randomized clinical trials that evaluate the effectiveness of different attachment designs for achieving optimal extrusion of lateral incisors. By determining the most effective attachment size for maxillary lateral incisor extrusion, this study can help improve treatment outcomes for orthodontic treatment with clear aligners and serve as a guide to assist clinicians in selecting the most effective attachment design.

Study Type

Interventional

Enrollment (Actual)

28

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Virginia
      • Richmond, Virginia, United States, 23298
        • Virginia Commonwealth University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Patients treated with either Comprehensive Invisalign or Invisalign Teen treatment
  • The maxillary arch has less than 6 mm of crowding or spacing
  • Maxillary lateral incisors have a minimum of 0.3 mm of extrusion prescribed in the Tooth Movement Table on the Invisalign ClinCheck for the first set of aligners
  • Maxillary lateral incisors within a normal range of bucco-lingual inclination
  • Patients 12 years of age or older and either the patient or legal guardian are able to give consent
  • Patients confirm good compliance throughout the study period

Exclusion Criteria:

  • Patients do not complete all aligners in the first phase as prescribed
  • Poor compliance recorded for aligner wear
  • Restorations placed or oral surgery completed prior to final scan
  • Midcourse intervention to improve tracking such as a bootstrap
  • Maxillary lateral incisors not tracking and noted by minimum of 1 mm of aligner material incisally displaced when aligner fully seated
  • Treatment plans include surgery or extractions
  • Maxillary lateral incisors with pathology and restorations
  • Missing teeth other than third molars
  • Patients with anterior crossbite

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Control/optimized for extrusion.aligners
The control will be Invisalign's optimized attachment which will be specifically optimized for extrusion.
Device: Corresponding treatment order in the prescription with Align Technology
Treating orthodontist placing the corresponding order in the prescription with Align Technology.
Device: Superimposition of final and initial positions of lateral incisors: Predicted model
Superimposition of final and initial positions of lateral incisors, two superimpositions will be completed. The pretreatment model will be superimposed with the predicted final model to establish the predicted movement of the maxillary lateral incisors
Experimental: Gingivally beveled 1x1x3mm aligners
Each set of aligners would be worn for a week/gingivally beveled 1x1x3mm
Device: Corresponding treatment order in the prescription with Align Technology
Treating orthodontist placing the corresponding order in the prescription with Align Technology.
Device: Superimposition of final and initial positions of lateral incisors: Gingivally beveled 1x1x3mm aligners
Superimposition of final and initial positions of lateral incisors, two superimpositions will be completed. The pretreatment model (Gingivally beveled 1x1x3mm aligners) will be superimposed with the posttreatment model to establish the actual movement of the maxillary lateral incisor.
Experimental: Gingivally beveled 1x1x4mm aligners
Each set of aligners would be worn for a week/gingivally beveled 1x1x4mm
Device: Corresponding treatment order in the prescription with Align Technology
Treating orthodontist placing the corresponding order in the prescription with Align Technology.
Device: Superimposition of final and initial positions of lateral incisors: Gingivally beveled 1x1x4mm aligners
Superimposition of final and initial positions of lateral incisors, two superimpositions will be completed. The pretreatment model (Gingivally beveled 1x1x4mm aligners) will be superimposed with the posttreatment model to establish the actual movement of the maxillary lateral incisor.
Experimental: Gingivally beveled 1x1x5mm aligners
Each set of aligners would be worn for a week/gingivally beveled 1x1x5mm
Device: Corresponding treatment order in the prescription with Align Technology
Treating orthodontist placing the corresponding order in the prescription with Align Technology.
Device: Superimposition of final and initial positions of lateral incisors: Gingivally beveled 1x1x5mm aligners
Superimposition of final and initial positions of lateral incisors, two superimpositions will be completed. The pretreatment model (Gingivally beveled 1x1x5mm aligners) will be superimposed with the posttreatment model to establish the actual movement of the maxillary lateral incisor.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Determine which of three different attachment sizes offers more predictable extrusion of maxillary lateral incisors in subjects treated with clear aligners compared
Time Frame: baseline until the clear aligner treatment is completed at 20 to 25 weeks
The aim of this prospective, randomized controlled trial is to determine which of three different attachment sizes (gingivally beveled 1x1x3 mm, gingivally beveled 1x1x4 mm, or gingivally beveled 1x1x5 mm) offers more predictable extrusion of maxillary lateral incisors in patients treated with clear aligners compared to control.
baseline until the clear aligner treatment is completed at 20 to 25 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Evaluate the accuracy of ClinCheck software
Time Frame: baseline until the clear aligner treatment is completed at 20 to 25 weeks
To evaluate the accuracy of ClinCheck software in predicting the three-dimensional final position of the lateral incisor following extrusion using the attachment designs tested.
baseline until the clear aligner treatment is completed at 20 to 25 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Virginia Commonwealth University

Investigators

  • Principal Investigator: Steven Lindauer, Virginia Commonwealth University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 31, 2025

Primary Completion (Actual)

June 1, 2026

Study Completion (Actual)

June 1, 2026

Study Registration Dates

First Submitted

February 3, 2025

First Submitted That Met QC Criteria

February 3, 2025

First Posted (Actual)

February 7, 2025

Study Record Updates

Last Update Posted (Actual)

June 8, 2026

Last Update Submitted That Met QC Criteria

June 5, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • HM20031880

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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