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Completed

NCT Number: NCT07771660

Comparison of Ertty Gap III and Facemask Therapy for Skeletal Class III Correction

This single-center, parallel-group randomized clinical trial compared 2 orthopedic treatment approaches in growing patients with skeletal Class III malocclusion associated predominantly with maxillary deficiency: the Ertty Gap III appliance and facemask therapy. Forty-two participants were randomly allocated in a 1:1 ratio to Ertty Gap III or facemask therapy. The primary objective was to compare the short-term skeletal effects of the 2 treatment protocols, with the ANB angle designated as the primary outcome. Skeletal, dentoalveolar, and soft-tissue outcomes were assessed using standardized lateral cephalometric radiographs obtained before treatment and at treatment completion.

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Key information

Conditions

Skeletal Class III Malocclusion

Age range

9 year–12 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Ankara University, Faculty of Dentistry, Department of Orthodontics

Ankara, 06560, Turkey (Türkiye)

About this study

Skeletal Class III malocclusion in growing patients may be associated with maxillary deficiency, mandibular prognathism, or a combination of both. Early orthopedic treatment directed toward maxillary advancement is commonly performed using facemask therapy. The Ertty Gap III appliance is an intraoral orthopedic appliance designed to apply Class III corrective forces through a different biomechanical configuration.

This prospective, single-center, parallel-group randomized clinical trial compared the short-term skeletal, dentoalveolar, and soft-tissue effects of the Ertty Gap III appliance with those of facemask therapy in growing patients with skeletal Class III malocclusion associated predominantly with maxillary deficiency. Forty-two eligible participants were randomly allocated in a 1:1 ratio to the Ertty Gap III or facemask group using concealed allocation.

Standardized lateral cephalometric radiographs were obtained before treatment (T0) and at completion of active orthopedic treatment (T1). The ANB angle was designated as the primary outcome. The between-treatment effect for ANB was evaluated by comparing posttreatment values between the groups after adjustment for the corresponding pretreatment value. Secondary and supportive exploratory outcomes included selected skeletal, dentoalveolar, occlusal, and soft-tissue cephalometric measurements.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Age between 9 and 12 years.
  • Late mixed or early permanent dentition.
  • Skeletal Class III malocclusion characterized by an A point-Nasion-B point (ANB) angle ≤ 0° and a Class III molar relationship.
  • Maxillary deficiency confirmed by clinical and cephalometric assessment, including evaluation of the Sella-Nasion-Point A (SNA) angle according to Steiner analysis (82° ± 2° as the reference) and clinical evidence of perinasal or midfacial deficiency.
  • In participants with associated mandibular prognathism, maxillary retrognathia was required to be the predominant skeletal component of the Class III discrepancy.
  • Anterior crossbite or an edge-to-edge incisal relationship.
  • No previous orthodontic or orthopedic treatment.

Exclusion criteria

  • Completed skeletal growth.
  • Skeletal Class III malocclusion attributable solely to mandibular prognathism without clinical or cephalometric evidence of maxillary retrognathia.
  • Presence of systemic disease.
  • Craniofacial syndromes or congenital craniofacial anomalies.
  • Temporomandibular joint disorders.
  • Congenital absence of maxillary lateral incisors.
  • Palatally displaced permanent canines.
  • Missing, extracted, or prematurely lost permanent first molars.

Treatment and study plan

Ertty Gap III Appliance

Device

The Ertty Gap III appliance is an intraoral orthopedic appliance designed for maxillary protraction in growing patients with skeletal Class III malocclusion. The maxillary component consists of a sagittally oriented 90° inverted Hyrax expansion screw with an acrylic pad extending from the palatal rugae toward the premaxillary region and posterior occlusal build-ups. The mandibular component consists of a lip bumper-lingual arch assembly supported by the mandibular first permanent molars. Bilateral 5/16-inch, 8-ounce Class III intermaxillary elastics are applied between the maxillary first-molar region and the mandibular lip-bumper notches. The sagittal Hyrax screw is activated once weekly with two consecutive quarter-turns. Patients are instructed to wear the appliance and intermaxillary elastics full time, except during meals, oral hygiene, and contact sports. Patients are monitored at 4-week intervals.

Facemask Therapy

Device

Conventional maxillary protraction was performed using a Petit-type facemask in combination with a 0.80-mm full-coverage vacuum-formed maxillary splint covering all maxillary teeth. Hooks were incorporated into the splint in the premolar region for attachment of bilateral protraction elastics. Maxillary expansion was not performed in order to isolate the effects of maxillary protraction. Bilateral protraction elastics delivered approximately 350 g of force per side, with the force vector directed approximately 30° downward from the occlusal plane. The applied force was verified using a force gauge at appliance delivery and at each follow-up visit. Participants were instructed to wear the facemask and elastics full time except during meals, oral hygiene, and contact sports. Follow-up visits were scheduled at 4-week intervals to assess appliance integrity, reinforce compliance, verify elastic force levels, and make necessary adjustments.

Primary outcomes

  1. Change in ANB Angle

    Time frame: Baseline to completion of orthopedic treatment (approximately 13 months; treatment continued until achievement of a positive overjet)

    Change in the ANB angle (degrees) from baseline to completion of orthopedic treatment, assessed on standardized lateral cephalometric radiographs. The ANB angle represents the sagittal skeletal relationship between the maxilla and mandible. A positive change indicates improvement in the sagittal maxillomandibular relationship.

Secondary outcomes

  1. Change in Sella-Nasion-Point A Angle (SNA)

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months)

    Change in the angle between the sella-nasion line and the nasion-point A line, measured in degrees on standardized lateral cephalometric radiographs.

  2. Change in Sella-Nasion-Point B Angle (SNB)

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months)

    Change in the angle between the sella-nasion line and the nasion-point B line, measured in degrees on standardized lateral cephalometric radiographs.

  3. Change in Gonion-Gnathion/Sella-Nasion Angle (GoGn/SN)

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the angle between the gonion-gnathion plane and the sella-nasion plane, measured in degrees on standardized lateral cephalometric radiographs.

  4. Change in Maxillary Incisor-to-Palatal Plane Angle (U1-PP)

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the angle between the long axis of the maxillary central incisor and the palatal plane, measured in degrees on standardized lateral cephalometric radiographs.

  5. Change in Incisor Mandibular Plane Angle (IMPA)

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the angle between the long axis of the mandibular central incisor and the mandibular plane, measured in degrees on standardized lateral cephalometric radiographs.

  6. Change in Overjet

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the horizontal distance between the maxillary and mandibular incisal edges, measured in millimeters on standardized lateral cephalometric radiographs.

  7. Change in Overbite

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the vertical overlap of the maxillary and mandibular incisors, measured in millimeters on standardized lateral cephalometric radiographs.

  8. Change in Maxillary First Molar-to-Pterygoid Vertical Distance (U6d-PTV)

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the horizontal distance from the distal surface of the maxillary first molar to the pterygoid vertical plane, measured in millimeters on standardized lateral cephalometric radiographs.

  9. Change in Nasolabial Angle

    Time frame: Baseline to completion of orthopedic treatment or the corresponding observation period (approximately 13 months).

    Change in the angle formed by the columella-subnasale and subnasale-upper lip lines, measured in degrees on standardized lateral cephalometric radiographs.

Interested in participating?

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Sponsors and collaborators

Lead sponsor

Ankara University

Other

Registry information

Official study title

Targeting the Premaxillary-Maxillary Suture for Skeletal Class III Correction in Growing Patients: Ertty Gap III Versus Facemask Therapy in a Randomized Clinical Trial

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
Aug 18, 2026
Registry last updated
Sep 15, 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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