Comparison of Single-Layer and Triple-Layer TPU MaxFlex Aligners After Intraoral Use (TPU-ALIGN)

April 27, 2026 updated by: Abdul Qadir, Ayub Medical College, Abbottabad

Effects of Intraoral Aging on Mechanical Properties and Surface Morphology of Single-Layer Versus Triple-Layer Thermoplastic Polyurethane (TPU) MaxFlex Aligner Sheets: A Randomized Controlled Trial

This study aims to compare two types of clear orthodontic aligner materials used in dental treatment: single-layer and triple-layer thermoplastic polyurethane (TPU) aligners (MaxFlex). Clear aligners are commonly used to straighten teeth and are preferred for their comfort and aesthetic appearance.

Participants will be provided with aligners and instructed to wear them for approximately 22 hours per day for 10 days. The aligners will be collected before use and after the 10-day period. The study will evaluate how the oral environment affects the properties of these materials over time.

Laboratory tests will be conducted to measure mechanical properties such as strength, flexibility, and deformation, as well as to examine surface changes under a microscope. The results of this study may help improve the performance and durability of aligners and contribute to better orthodontic treatment outcomes.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Clear aligner therapy (CAT) has become an increasingly popular alternative to fixed orthodontic appliances due to its aesthetic advantages, improved patient comfort, and ease of oral hygiene maintenance. Thermoplastic materials, particularly thermoplastic polyurethane (TPU), are widely used in the fabrication of aligners due to their favorable mechanical and elastic properties.

Recent advancements in aligner materials have led to the development of multilayer TPU systems designed to enhance flexibility, force delivery, and clinical performance. Triple-layer TPU aligners typically consist of a soft inner layer for patient comfort, a rigid intermediate layer for structural strength, and a flexible outer layer to improve adaptability and fit. In contrast, single-layer TPU aligners are composed of a homogeneous material and are generally more cost-effective.

Despite these developments, limited evidence exists regarding the comparative behavior of single-layer and multilayer TPU materials following intraoral exposure. The oral environment, characterized by temperature fluctuations, moisture, masticatory forces, and enzymatic activity, may contribute to material degradation, potentially affecting aligner performance.

This randomized controlled trial is designed to evaluate the effects of intraoral aging on the mechanical properties and surface morphology of single-layer and triple-layer TPU aligners (MaxFlex). Participants will be randomly assigned to receive one type of aligner material and will be instructed to wear the aligners for a standardized duration of 10 days (minimum 22 hours per day).

Aligners will be collected at baseline (prior to intraoral use) and after the 10-day wear period. Following retrieval, samples will undergo standardized cleaning procedures before laboratory analysis.

Mechanical testing will be performed using dynamic mechanical analysis to assess tensile properties, stress relaxation behavior, and creep characteristics. Surface morphology will be evaluated using scanning electron microscopy to identify features such as roughness, cracks, and voids. Additionally, Fourier transform infrared spectroscopy will be used to detect potential chemical changes in the material composition.

The primary objective of this study is to compare the mechanical performance of single-layer and triple-layer TPU aligners before and after intraoral use. Secondary outcomes include evaluation of surface morphology and chemical structure changes associated with intraoral aging.

The findings of this study are expected to provide insight into the durability and clinical performance of different aligner materials, which may help guide material selection and improve orthodontic treatment outcomes.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
66

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

  • Pakistan
    • Punjab Province
      • Lahore, Punjab Province, Pakistan
        • Akhtar Saeed Medical & Dental College

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

Patients aged 18-30 years Fully erupted permanent dentition Good periodontal health Patients undergoing orthodontic treatment with clear aligners Mild crowding or spacing requiring labiolingual tooth movement Willingness to wear aligners for at least 22 hours per day Provision of informed consent

Exclusion Criteria:

Use of aligners from manufacturers other than study-specific TPU aligners Damaged or fractured aligners Poor compliance (wear time less than 22 hours/day) Presence of parafunctional habits (e.g., bruxism) Hypodontia or partially erupted dentition Cases involving bonded attachments on maxillary incisors Cases requiring rotational movement of maxillary incisors Patients with systemic or oral conditions affecting saliva composition or the oral environment

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: Other
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Single-Layer TPU Aligner Group
Participants in this group will receive single-layer thermoplastic polyurethane (TPU) MaxFlex aligners. The aligners will be worn intraorally for 10 days for a minimum of 22 hours per day under standardized conditions. Aligners will be collected at baseline and after the wear period for evaluation of mechanical properties and surface morphology.
Device: Single-Layer Thermoplastic Polyurethane Aligner
Single-layer thermoplastic polyurethane (TPU) clear aligners fabricated from a homogeneous TPU sheet using thermoforming techniques. These aligners are designed to deliver orthodontic forces for tooth movement. Participants will be instructed to wear the aligners intraorally for 10 days for a minimum of 22 hours per day. The aligners will be evaluated before use and after intraoral exposure to assess changes in mechanical properties and surface morphology.
Experimental: Triple-Layer TPU Aligner Group
Participants in this group will receive triple-layer thermoplastic polyurethane (TPU) MaxFlex aligners consisting of a soft inner layer, a rigid intermediate layer, and a flexible outer layer. The aligners will be worn intraorally for 10 days for a minimum of 22 hours per day. Aligners will be collected at baseline and after use for mechanical and surface analysis.
Device: Triple-Layer Thermoplastic Polyurethane Aligner
Triple-layer thermoplastic polyurethane (TPU) clear aligners composed of a multilayer structure including a soft inner layer, a rigid intermediate layer, and a flexible outer layer. These aligners are fabricated using thermoforming techniques and are designed to provide improved force delivery and adaptability. Participants will wear the aligners intraorally for 10 days for at least 22 hours per day. Pre- and post-use evaluations will be conducted to assess mechanical properties and surface morphology changes.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Effect of Oral Environment on Elastic Modulus of TPU Aligners
Time Frame: Baseline (0 week) and after 2 weeks of intraoral use (minimum 22 hours/day)
This outcome measures the change in elastic modulus (MPa) of thermoplastic polyurethane (TPU) orthodontic aligners following intraoral exposure. Measurements are obtained using a dynamic mechanical analyzer and compared between single-layer and multilayer TPU aligners at baseline and after two weeks of clinical use to assess changes in stiffness and material integrity.
Baseline (0 week) and after 2 weeks of intraoral use (minimum 22 hours/day)
Effect of Oral Environment on Stress Relaxation of TPU Aligners
Time Frame: Time Frame: Baseline (0 week) and after 2 weeks of intraoral use (minimum 22 hours/day)
This outcome measures the percentage stress relaxation (%) of TPU aligners following intraoral exposure. Stress decay over time is recorded using a dynamic mechanical analyzer and compared between single-layer and multilayer TPU aligners at baseline and after two weeks to evaluate force retention capacity.
Time Frame: Baseline (0 week) and after 2 weeks of intraoral use (minimum 22 hours/day)
Effect of Oral Environment on Creep Behavior of TPU Aligners
Time Frame: Time Frame: Baseline (0 week) and after 2 weeks of intraoral use (minimum 22 hours/day)
This outcome measures creep (% strain) in TPU aligners under constant stress conditions using a dynamic mechanical analyzer. Comparisons are made between single-layer and multilayer TPU aligners at baseline and after two weeks to assess susceptibility to permanent deformation.
Time Frame: Baseline (0 week) and after 2 weeks of intraoral use (minimum 22 hours/day)

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ayub Medical College, Abbottabad

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 13, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 5, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 16, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 19, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 27, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 5, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 5, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 27, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • TPU-ALIGNER-01
  • no identifier (Other Identifier: Akhtar Saeed Medical & Dental College)

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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