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

Ankara University42 enrolled

Overview

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.

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

Interventions

Ertty Gap III ApplianceDEVICE

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 TherapyDEVICE

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.

Eligibility

Sex: ALLMin age: 9 YearsMax age: 12 Years

Medical Language ↔ Plain English

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.

Outcomes

Primary Outcomes

Change in ANB Angle

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.

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

Secondary Outcomes

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

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

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

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

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

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

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

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