Innovative Protocol for Early Class III Correction with Aligner and Facemask: A Case Report

Romina Vignolo Lobato1*, and David Gonzalez Zamora2
1*Professor of the Master's Degree in Advanced Orthodontics. European University of Madrid, Professor of the Master's Degree in Orthodontics and Orthopaedics. San Pablo CEU University – Madrid, Exclusive Private Practice in Madrid
2Professor of the Master's Degree in Orthodontics and Orthopaedics. San Pablo CEU University - Madrid. Exclusive Private Practice in Madrid
*Corresponding author: Romina Vignolo Lobato, Avenida Dr. Marañón 17 1º A. Majadahonda . 28220. Madrid, Spain
Citation: Vignolo Lobato R and Gonzalez Zamora D. Innovative Protocol for Early Class III Correction with Aligner and Facemask : A Case Report. J Oral Med and Dent Res. 6(1):1-16.
Received: October 11, 2024 | Published: January 10, 2025
Copyright© 2025 genesis pub by Vignolo Lobato R, et al. CC BY-NC-ND 4.0 DEED. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives 4.0 International License. This allows others distribute, remix, tweak, and build upon the work, even commercially, as long as they credit the authors for the original creation.
DOI: https://doi.org/10.52793/JOMDR.2025.6(1)-81
Abstract
The purpose of this case report is to describe the treatment of a Class III malocclusion in the primary dentition using maxillary expansion with aligners, in combination with a facemask anchored to buttons or hooks integrated into the aligners. The treatment objectives included correcting anterior and posterior crossbites, achieving maxillary protrusion through maxillary traction, improving mandibular dynamics, and balancing the facial profile. Skeletal and dental changes were evaluated, revealing a significant increase in the SNA angle and harmonization of the anteroposterior relationship according to Wits values. Vertical skeletal characteristics remained stable throughout the treatment.
The success of the treatment is attributed to accurate diagnosis, appropriate planning, and strong patient and family compliance. The results underscore the importance of early intervention in Class III malocclusion, particularly when the maxilla is the primary etiological factor, highlighting the crucial role of orthopedic appliances and treatment adherence in achieving favorable craniofacial growth.
Keywords
Class III treatment; Maxillary hypoplasia; Expansion; Palatal expansion technique; Face mask therapy; Interceptive orthodontics; Orthopedics; orthodontic.
Introduction
Class III malocclusion is one of the most notorious malocclusions, and is therefore often identified early, since differences in skeletal size, already exist regarding occlusion Class I as early as 4-5 years of age [1]. It has been documented that Class III malocclusion tends to exacerbate during growth, especially from adolescence onwards. Therefore, in children, this malocclusion may not be fully defined, and unestablished facial and occlusal features may make diagnosis difficult [2]. The earlier the interceptive phase is initiated, the greater the orthopedics effects, often to the detriment of the inevitable orthodontic effects [3]. In Class III malocclusion, the mandibular arch is more advanced relative to the maxillary arch, and this condition tends to worsen with age, which has led to controversy among researchers regarding diagnosis, prognosis and treatment [4].
The etiology of this problem may be of genetic origin [5] which is associated with a poorer prognosis [6] or of environmental origin, influenced by a more anterior and inferior position of the tongue [7] as well as by habits and oral breathing [8]. According to the WHO, this type of alteration ranks third after dental caries and periodontitis [9]. Its incidence varies among different ethnic groups, ranging from 0 to 26% worldwide [10-11]. The prevalence of Class III malocclusions also varies considerably, ranging from 1 to 4 % in Caucasians, 4 to 12 % in Chinese and 9 to 19 % in Koreans [12-13].
In relation to etiology and underlying skeletal dysmorphia, several studies have indicated that both mandibular prognathism and maxillary retrognathism are equally frequent in individuals with Class III anomalies (with a range of 32 to 63 % of patients presenting with a retrusive maxilla) [14,16]. Furthermore, in the majority of patients, a combination of both skeletal aberrations is observed. With an increasing number of studies highlighting the maxillary component in Class III skeletal patterns [17, 18], and with the understanding that the therapeutic influence on the growing mandible is limited (and may involve unwanted side effects for the temporomandibular joint), the standard therapy for mild to moderate Class III discrepancies, especially in growing patients, is maxillary protraction to correct the maxillary deficiency.
Early treatment of Class III malocclusion aims to create an environment conducive to proper dentofacial development in order to prevent progressive hard and soft tissue changes, improve skeletal discrepancies and provide optimal conditions for future craniofacial growth. This early approach offers benefits in aesthetics and facial profile, prevents periodontal recession and tooth wear, improves temporomandibular joint (TMJ) function, reduces negative psychosocial effects in children and reduces the need for orthognathic surgery, thus simplifying later therapeutic phases [19. 21]. In addition, when the face mask is combined with maxillary expansion, an increase in airway volume is achieved, resulting in improved respiratory function [22-24].
The purpose of this case report is to describe the treatment of a Class III malocclusion in the primary dentition using maxillary expansion with clear aligners in combination with a face mask with button or hook traction integrated into the aligner.
Development
Maxillary expansion and anterior traction facial mask
The treatment of the spectrum of Class III malocclusions represents one of the most complex challenges in the field of orthodontics and orthopedic orofacial therapy. Since the late 19th century, a variety of treatment strategies have been proposed, ranging from the use of functional appliances [25-27], chin rest therapy [28-29] and face mask therapy [30-34] to surgical correction by split sagittal osteotomy and LeFort I osteotomy.
There are few systematic literature review studies, and even fewer including statistical meta- analyses on the effects and effectiveness of maxillary protraction therapy with the use of an orthopedic face mask [35-37]. The influence and possible improvement of maxillary protraction through maxillary expansion has been the subject of debate [38-42]. In a 1999 review, concluded that expansion slightly improves the effect of maxillary protraction and reduces tooth movement, although they noted that the clinical significance is low [35]. The review of face mask therapy, conducted by Cordasco et al. and published in 2014, also partially addressed the aspect of expansion, indicating that no significant improvement was observed with rapid palatal expansion [37]. In 2005, introduced a novel approach, proposing a protocol of alternating activation and deactivation of the maxillary expansion appliance (altRAMEC) prior to the application of class III mechanics, which improved the therapeutic effect in the hypoplastic maxilla [43].
The treatment of Class III malocclusion in growing patients with the use of a face mask is effective for the correction of sagittal discrepancy. The need for a single transverse expansion is mainly determined by dentoalveolar anomalies in the transverse dimension, such as edge-to-edge occlusion or crossbites. Recent findings underline that there is no significant improvement in maxillary protraction when additional expansion is performed [44].
Similarly, the literature includes studies comparing the effectiveness of clear aligners with rapid maxillary expansion (RME) in terms of maxillary expansion. Although further research is needed to confirm these findings, the available data indicate a significant increase in palatal volume, as well as in other evaluated parameters such as air volume. While cases treated with rapid palatal expanders demonstrate a slight superiority over clear aligners in all evaluated parameters, this difference has not been found to be statistically significant [45-47].
Several clinical studies, systematic reviews and meta-analyses have demonstrated the skeletal effects of face mask treatment, both in combination with and without rapid maxillary expansion (RME) as described.
Thermoplastic materials, trimline on the aligner and integrated attachments for maxillary traction
Thermoplastic materials
Transparent aligners are manufactured from various thermoplastic materials, the properties of which are altered during the thermoforming process. In addition, the intraoral environment significantly influences the performance of these aligners. According to [48], the mechanical characteristics of the polymer used, the daily frequency with which the aligner is removed and the magnitude of tooth activation are determining factors in the forces generated by the aligner [49].
Currently, thermoplastic materials used in the manufacture of aligners include polyethylene terephthalate (PET-G), polypropylene, polycarbonate (PC), thermoplastic polyurethanes (TPU) and vinyl ethyl acetate [50].
In our proposed protocol, a specific combination of aligners is used at each stage of treatment: initially, a PET-G aligner, followed by a TPU aligner. In the proposed protocol, a specific combination of aligners is used at each stage of treatment: initially, a thermoformed multilayer copolyester and polyurethane composite (TPU + PET-G) plastic, followed by a TPU aligner. Previous studies have demonstrated that the forces applied by multilayer TPU + PET-G aligners significantly decrease during the first eight hours of wear, after which they reach a point of stability [51]. This system counteracts the reduction in force by utilizing two aligners per stage; the first, a TPU + PET-G multilayer aligner, is worn during the initial days, followed by a new polyurethane (TPU) aligner, which has shown less force degradation compared to other materials [52].
The combination of these two types of materials improves the predictability of complex tooth movements, ensuring more effective control of mass shifts and torque changes.
Variable trimline
The trimline on orthodontic aligners refers to the edge that delineates how far the aligner extends over the tooth and gum. This trimline can influence several aspects of aligner treatment, including:
- Tooth movement.
- Patient comfort, 3.
- Aligner stability.
- Aesthetics [53-55].
It is critical that the trimline be straight and 2.5 mm above the gingival margin to meet specific protocol requirements and achieve the desired dentoalveolar and skeletal movement (Figure 1).
Figure 1: Variable trim line.
Buttons and Hooks Integrated into the Aligner
Buttons and hooks integrated directly into the aligners provide an additional attachment point for the use of elastics during treatment. This tool can be added to any part of the aligner allowing the elastics for traction to the face mask to engage in any direction. With a solid structure they are designed to facilitate efficient tooth movement, allowing the teeth to move without being directly affected by the forces of the elastics, withstanding a force of up to 500g (Figure 2).
Figure 2: angel Button™ angel Hook™.
Material and Method
The purpose of the clinical case presented here is to demonstrate that early management of Class III malocclusions offers better results, and how the use of the protraction mask followed by maxillary orthopedic therapy is highly beneficial for these patients.
Maxillary expansion will be carried out using clear aligners, designed with a high cut-off line. These aligners will simulate the mass movements of rapid maxillary expansion (RME) without individual movements of the upper arch teeth. For each stage of treatment, a set of two aligners will be used: the first (MASTER CONTROL S™), made of TUP+ PET-G material, will initiate movement due to its more flexible properties, while the second (MASTER CONTROL™), made of TPU, will consolidate movement due to its more rigid characteristics. Each aligner will be used for five days, for a total of ten days per phase. The magnitude of expansion in each stage will be 0.2 mm, and the total will vary according to the severity of the case (Figure 3).
Figure 3: Procedure for palatal expansion using aligners
The aligners will be equipped with a button or hook placed between the lateral incisor and the primary canine, which will serve to connect the maxilla to the face mask stem Figure 2. The face mask has an adjustable anterior arch, which is used to apply traction on the maxilla using elastics. During maxillary expansion, elastics will be used to provide a force of 300-500 grams per side, and it is recommended that the mask be worn for an average of 12 hours per day (Figure 4).