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NCT Number: NCT07485478

Effects of Invisalign Palatal Expander vs Rapid Palatal Expander With Facemask in Growing Class III Patients

The goal of this clinical trial is to compare two types of palatal expanders used with a facemask in children who have skeletal Class III and a narrow upper jaw. The study will compare the Invisalign Palatal Expander (IPE) and the Rapid Palatal Expander (RPE). Researchers want to learn how these devices affect jaw bones and tooth position. They also want to learn about children's and parents' experiences during treatment.

The main questions this study aims to answer are:

Do IPE and RPE widen the upper jaw differently?

Do they cause different changes in tooth position?

How do children and parents describe their treatment experience?

Participants will be children aged 8 to 12 years who have skeletal Class III and a narrow upper jaw. Children with craniofacial conditions, previous upper jaw expansion, or medical conditions that prevent orthodontic treatment will not take part. Parents and children must give consent before joining the study.

Participants will:

Be assigned to receive either IPE or RPE

Expand the upper jaw to 7 mm (0.25 mm per day)

After expansion, wear a facemask for at least 12 hours per day for 6 to 8 months

Have cone-beam computed tomography (CBCT) scans taken before expansion, after expansion, and after facemask treatment

Take part in an interview with a parent after expansion

Researchers will use CBCT images to measure changes in jaw bones and tooth position. The main outcomes are changes in jaw bones and tooth position. Secondary outcomes include children's and parents' experiences during treatment.

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Key information

Conditions

Skeletal Class III Malocclusion Transverse Maxillary Deficiency

Age range

8 year–12 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients aged between 8 and 12 years
  • Patients in the mixed dentition or early permanent stage have at least three stable teeth per quadrant, good oral hygiene, and healthy periodontal tissues
  • Patients with maxilla-mandibular discrepancies; skeletal class III is indicated by an ANB angle < 0 degrees or a Wits appraisal value that is negative, and Maxillary constriction is characterized by posterior crossbite teeth or having a maxillary width below the norm value.

Exclusion criteria

  • Patients with craniofacial anomalies such as cleft lip and palate
  • Patient with a prior history of maxillary expansion.
  • Patients who have systemic conditions that contraindicate orthodontic treatment.

Treatment and study plan

Invisalign Palatal Expander (IPE)

Device

Participants will be treated with an Invisalign palatal expander. Participants will be instructed to wear the appliance full-time, except when brushing and flossing their teeth, and to change the device daily (0.25 mm) until the planned transverse width (7 mm.) is achieved.

Rapid Palatal Expander (RPE)

Device

Participants will be treated with a bonded RPE. Their parents are instructed to activate the screw once per day (0.25 mm) until the expansion screw reaches 7 mm.

Primary outcomes

  1. Maxillary skeletal change

    Time frame: T0: Baseline (Day 0) - before initiation of maxillary expansion T1: Post-expansion - after completion of 7 mm expansion with RPE or IPE T2: Post-protraction - after 6 months of active maxillary protraction

    • Anterior and posterior midpalatal suture width
    • Anterior apical base width inferior
    • Anterior apical base width superior
    • Posterior apical base width
    • Anterior width at mid-alveolar level
    • Posterior width at alveolar crest level

  2. Maxillary dental change

    Time frame: T0: Baseline (Day 0) - before initiation of maxillary expansion T1: Post-expansion - after completion of 7 mm expansion with RPE or IPE T2: Post-protraction - after 6 months of active maxillary protraction

    • Intermolar width at occlusal surface
    • Intermolar width at palatal root apices
    • Right first molar angulation
    • Left first molar angulation

Secondary outcomes

  1. Functional and perceptual experiences and parental involvement associated with the use of Rapid Palatal Expander (RPE) and Invisalign Palatal Expander (IPE).

    Time frame: Single assessment at 28 days (± 5 days) after appliance insertion

    The functional and perceptual experiences of pediatric patients and their parents, as well as parental involvement in appliance management, will be evaluated through semi-structured face-to-face interviews. Interviews will take place at the Orthodontic Clinic, Faculty of Dentistry, Mahidol University, using a topic guide developed from the study conceptual framework. The interviews will explore appliance-related factors, functional impacts on the child (pain, speech, mastication, and oral hygiene), emotional and perceptual responses of both children and parents, parental involvement in appliance management, treatment compliance, and perceived treatment outcomes. Each interview will last approximately 30 minutes, with audio recording and field notes used for qualitative analysis.

Sponsors and collaborators

Lead sponsor

Mahidol University

Other

Registry information

Official study title

Effects of the Invisalign® Palatal Expander (IPE) vs. Rapid Palatal Expander With Facemask in Growing Skeletal Class III Patients: A CBCT Randomized Clinical Trial

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Mar 20, 2026
Registry last updated
Mar 20, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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