Skeletal and Dentoalveolar Effects of Functional Clear Aligner Therapy in Growing Patient With Skeletal Class III Malocclusion

July 10, 2026 updated by: Mansoura University
The purpose of this study is to evaluate the skeletal, dentoalveolar & soft tissue effects of functional clear aligner therapy in growing patient with Skeletal class III malocclusion. Skeletal class III discrepancy has been a therapeutic challenge due to the fact that its therapeutic management seeks not only the correction of the malocclusion but also the aesthetic component of the patient which is affected according to the severity of the discrepancy. Early diagnosis, planning of adequate therapeutic time and choice of devices to correct malocclusion are the essential keys to successful management of class III in all its forms. Functional appliances are commonly used for the treatment of skeletal class III malocclusion. Removable aesthetic appliance therapy as clear aligner becomes an increasingly common addition to the orthodontic armamentarium. It offers certain advantages over traditional appliance orthodontic treatments; these include fewer clinical emergencies and improved aesthetics, comfort, oral hygiene, periodontal health, and lack of soft tissue irritation. The aim of this study is to evaluate the skeletal, dentoalveolar & soft tissue effects of functional clear aligner therapy in growing patient with Skeletal class III malocclusion. A total of four blocks are digitally designed, with two blocks placed in the maxillary aligner in the anterior region and two blocks placed in the mandibular aligner in the posterior region. The blocks are designed as inclined planes to guide mandibular repositioning, simulating the reverse twin block mechanism. The upper and lower bite blocks are designed to interact with each other through coherent, specifically designed 70° inclined planes, allowing controlled mandibular repositioning during occlusal contact. Optimized attachments are digitally placed on selected teeth to enhance aligner retention and control tooth movement. Oral Health Related Quality of Life (OHRQoL) assessments will be incorporated as an outcome measure in addressing and measuring clinically meaningful change.

Study Overview

Status

Enrolling by invitation

Intervention / Treatment

Detailed Description

. Fifteen patients with mild skeletal class III were selected according to specific inclusion criteria and included in the study, these patients were treated with Functional Clear Aligner to evaluate its skeletal, dentoalveolar & soft tissue effects.

Bite registration: The patient intraoral scan will be performed according to the constructor's instructions. The software interface of the intra-oral scanner allows the registration of two different maxillo-mandibular relationships (MMRs).The first MMR scan will be registered in maximum intercuspation occlusion. The second scan will be registered in planned mandibular retrusion for Aesthetic functional appliance design. Bite registration will be done with the mandible in the most retruded position with an inter- incisal clearance of 2 mm and a clearance of 6 mm in the posterior segment.

To obtain an optimal and reproducible MMR scan in mandibular retrusion, curable resin will be used as a bite registration material. Two pieces of resin will be used as bite registration material, placing them (one piece per each side of the dentition) onto the occlusal surface of the posterior dentition. Then mandible will be guided in the most retruded position, this will be performed with a brief preliminary patient training. When the mandible reaches the desired backward position, the occlusal resin will be cured on both sides. Then the two registration pieces of resin will be fully cured outside of the mouth.

Once fully polymerized they will be checked for integrity, and they will be placed in occlusion to check that final mandibular retrusion is adequate and conforms to planned retrusion. Subsequently, patient maxillo-mandibular relationship in mandibular retrusion will be scanned.

During MMR scan acquisition on the right side, only the left piece of resin will be used to maintain mandibular retrusion. Conversely, during MMR scan acquisition on the left side, only the right piece of resin will be used. At the end of the MMR acquisition process, the software will be able to reorient the maxillary and mandibular scan according to the MMR.

Appliance construction: The steps of appliance construction are as follows:

  1. Import of Digital Scans Digital intraoral scans of the maxillary and mandibular arches are imported into the orthodontic planning software.
  2. Software Planning and Treatment Setup All software planning steps are performed, including model alignment, occlusal setup, and registration of the construction bite.
  3. Placement of Attachments Optimized attachments are digitally placed on selected teeth to enhance aligner retention and control tooth movement.
  4. Design of Mandibular Advancement Blocks A second design phase is performed to incorporate the mandibular advancement blocks. A total of four blocks are digitally designed, with two blocks placed in the maxillary aligner in the anterior region and two blocks placed in the mandibular aligner in the posterior region. The blocks are designed as inclined planes to guide mandibular repositioning, simulating the reverse twin block mechanism. The upper and lower bite blocks are designed to interact with each other through coherent, specifically designed 70° inclined planes, allowing controlled mandibular repositioning during occlusal contact.

    After the design process, the generated three-dimensional models are exported as files with STL extension and produced using different procedures according to their specific purposes.

  5. 3D Printing of Aligner Models The finalized digital files are used for three-dimensional printing of the aligner models.
  6. Thermoforming of Clear Aligners Clear aligners are fabricated by thermoforming thermoplastic sheets over the printed models.

The appliance construction workflow, including digital scanning, virtual treatment planning, attachment design, mandibular advancement block construction, STL file export, three-dimensional printing, and thermoforming of clear aligners, was performed according to previously described digital orthodontic and clear aligner protocols.

Clinical application:

  1. Bonding of Attachments

    Composite attachments are bonded on the facial surface of upper and lower central incisors and the upper and lower first permanent molars according to the digitally planned attachment design:

    Intra-oral bonding procedure will be started with the etching of the facial surface of the maxillary and mandibular central incisors and first permanent molars with (Meta Etchant) for 15-20 seconds. Etched dental surfaces will be washed and dried with chair air-flow and light-cured dental bonding agent (ORTHOSOLO from Ormco) will be applied to the conditioned dental surfaces and then polymerized for 5 seconds.

    The Attachments Template is loaded with the bonding material (SimpliShade TM Bulk Fill Flow composite from KERR TM) and positioned over the planned teeth to ensure precise placement of the attachments.

    Then the bonding material will be polymerized for 60 seconds for each attachment, and the template will be carefully removed and then the excess composite will be removed with Tungsten carbide orthodontic bur.

    Proper positioning and adaptation of the attachments are clinically verified to ensure optimal aligner retention and effective force delivery.

  2. Appliance Delivery The maxillary and mandibular clear aligners incorporating the reverse twin block design are inserted intraorally. The fit and proper seating of both aligners are carefully checked.
  3. Occlusal Verification The interaction between the upper and lower bite blocks is evaluated to confirm correct engagement of the inclined planes during mandibular closure. The mandible is guided into the predetermined therapeutic position upon occlusal contact.
  4. Patient Instructions Patients are instructed to wear the clear aligners for 20-22 hours per day, removing them only during meals and oral hygiene procedures. Detailed instructions regarding insertion, removal, cleaning, and storage of the aligners are provided.

The clinical procedures, including bonding of attachments using a template, appliance delivery, occlusal verification, and patient instructions, were performed according to established protocols for clear aligner therapy.

Study Type

Interventional

Enrollment (Estimated)

15

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

    • Dakahlia Governorate
      • Al Mansurah, Dakahlia Governorate, Egypt
        • Faculty of Dentistry, Mansoura 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

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Patients' age (8-11) years (CVM stages 2-3)
  • Mild class III skeletal pattern (Wits appraisal = 0 to -8)
  • Mild to moderate reverse overjet (-1 to -4)
  • Overbite (1-5)
  • Growing patients
  • Average or below average maxillary-mandibular plane angle and lower facial height
  • Mild incisors compensations

Exclusion Criteria:

  • Severe class III skeletal pattern
  • Long facial height
  • Bad oral hygiene
  • Systemic condition that may interfere with treatment

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: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Growing patients with mild skeletal class III
Functional Clear Aligner
A customized functional clear aligner appliance designed as a reverse twin block for growing patients with skeletal Class III malocclusion. The appliance incorporates digitally designed anterior maxillary and posterior mandibular bite blocks with 70° inclined planes to guide controlled mandibular repositioning while maintaining the esthetic and functional advantages of clear aligner therapy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in skeletal cephalometric measurements
Time Frame: Baseline and at the end of active treatment.
Anteroposterior and vertical skeletal changes will be assessed using standardized lateral cephalometric radiographs obtained at baseline and at the end of treatment. The evaluated parameters include SNA (°), SNB (°), ANB (°), Wits appraisal (mm), lower anterior facial height (LAFH, mm), upper anterior facial height (UAFH, mm), total anterior facial height (TAFH, mm), posterior facial height (PFH, mm), Frankfort mandibular plane angle (FMA, °), and Y-axis angle (°).
Baseline and at the end of active treatment.
Change in dentoalveolar cephalometric measurements
Time Frame: Baseline and at the end of active treatment.
Dentoalveolar changes will be assessed using standardized lateral cephalometric radiographs obtained at baseline and at the end of treatment. The evaluated parameters include upper incisor inclination to the SN plane (U1-SN, °), lower incisor inclination to the mandibular plane (IMPA, °), interincisal angle (°), U1-NA (mm and °), and L1-NB (mm and °)
Baseline and at the end of active treatment.
Change in soft tissue cephalometric measurements
Time Frame: Baseline and at the end of active treatment.
soft tissue changes will be assessed using standardized lateral cephalometric radiographs obtained at baseline and at the end of treatment. The evaluated parameters include upper lip to E-line (UL-E, mm), lower lip to E-line (LL-E, mm), and nasolabial angle (°).
Baseline and at the end of active treatment.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
OHRQoL (Oral Health-related Quality of Life) assessments are being incorporated into clinical studies and trials to measure efficaciousness of treatment with the goal of improving care.
Time Frame: 12 months

Studies involving OHRQoL seek to measure changes in scores from baseline to post-treatment.

The greater the malocclusion (skeletal class III), the lower the QoL. Researchers studying oral health problems have used OHRQoL as an outcome measure to determine the effect of treatment on QoL.

The use of OHRQoL as an evaluative outcome measure is congruent with patientcentered care. Along with other clinical assessments, it allows oral healthcare professionals to evaluate the efficacy of treatment protocols from patients' perspectives.

OHRAoL accurately weigh the risks and benefits associated with treatment. In addition, it provides evidence that costs associated with treatment protocols are worth the expense if they generally improve patients' OHRQoL we should consider sociocultural and psychological factors when assessing needs, outcomes, and clinical practice.

A final consideration in the use of OHRQoL as an outcome measure is addressing and measuring clinically meaningful change.

12 months

Collaborators and Investigators

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

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)

February 12, 2026

Primary Completion (Estimated)

February 13, 2027

Study Completion (Estimated)

July 13, 2027

Study Registration Dates

First Submitted

July 4, 2026

First Submitted That Met QC Criteria

July 10, 2026

First Posted (Actual)

July 14, 2026

Study Record Updates

Last Update Posted (Actual)

July 14, 2026

Last Update Submitted That Met QC Criteria

July 10, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

  • Eman Elsayed Ali Hashish

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

There is no plan to make de-identified individual participant data (IPD) available to other researchers.

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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