Effectiveness of Elastodontic Devices for Correcting Sagittal Malocclusions in Mixed Dentition Patients: A Scoping Review

Elastodontics is an interceptive orthodontic therapy that uses light and biological elastic forces through preformed or custom-made removable orthodontic appliances. This study aims to evaluate the effects of elastodontic devices on correcting sagittal discrepancies in growing subjects with mixed dentition. Electronic research was conducted on four databases: PubMed, Scopus, EMBASE, and Web of Science. Data were extracted based on the first author, year of publication, setting and country, study design, sample characteristics, sample size calculation, type of malocclusion, intervention, control group type, compliance, follow-up, and cephalometric measurements. Sixteen studies were included in the final review. Most studies observed a statistically significant reduction (p < 0.05) in SNB and ANB angles. Ten studies reported a reduction in overjet, while eight studies found no change in facial divergence. Comparisons with conventional functional devices revealed no consensus on the skeletal and dentoalveolar effects. Elastodontic appliances significantly improve cephalometric and dentoalveolar parameters, potentially correcting skeletal and dental relationships. However, result variability and unclear advantages over traditional appliances highlight the need for further research.


Introduction
Early intervention for malocclusion during the mixed dentition phase is highly recommended, particularly in cases where alterations in sagittal relationships present a significant risk of dental trauma to the upper incisors [1].Interceptive orthodontic therapy represents a preventive approach to treating malocclusion in pediatric patients.It is based on the understanding that signs of various malocclusions are frequently identifiable during both early and late mixed dentition stages [2,3] and that they do not self-correct with age [4].However, a consensus on the effectiveness of interceptive therapy has not been reached.Some studies suggest that early treatment may lead to stable occlusion, while others indicate that children would not benefit from early treatment aside from an increase in self-esteem [5][6][7].
Interceptive treatment becomes particularly relevant when addressing factors that disrupt the harmonious development of the maxillary and mandibular arches, often leading to skeletal and dento-alveolar compensations to maintain stable function and occlusion.Elastodontics is an interceptive orthodontic therapy that utilizes light and biological elastic forces through preformed or custom-made removable orthodontic appliances crafted from biomedical silicone or other elastic materials.These devices are activated by the patient's muscle function to correct malocclusions in growing patients, aiming to eliminate functional disturbances, correct tooth positions, and potentially influence growth [8,9].
The material of elastodontic devices facilitates orthodontic movement in synergy with the neuromyofascial system, while the vestibular flanges prevent perioral muscles from affecting tooth movement.Previous evidence suggests that elastomers could be effective in promoting significant clinical improvement in early signs of malocclusions such as crowding, overbite, overjet, and sagittal molar relationships.These devices are primarily designed for the treatment of orthopedic-orthodontic issues during the developmental age and, therefore, are used in deciduous or mixed dentition [10].
Nowadays, orthodontists have access to a wide range of easy-to-wear devices that act comprehensively on the stomatognathic system, seamlessly integrating with the neuromuscular system and requiring fewer patient check-ups [11].These devices exert threedimensional effects on all structures of the stomatognathic apparatus, correcting functional issues of soft tissues and promoting the restoration of oral, perioral, and lingual muscle function [12,13].
No previous scoping reviews have evaluated the outcomes of elastodontic devices using cephalometric measurements.Therefore, this study aims to assess the effects of elastodontic devices on correcting sagittal discrepancies in growing subjects with mixed dentition through cephalometric evaluation.A secondary objective is to compare the outcomes of these devices with conventional orthodontic devices and untreated groups.

Materials and Methods
The review was conducted in adherence to the protocol established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for conducting Scoping Reviews (PRISMA-ScR) [14].This scoping review was not registered.
To define the parameters of the research strategy, we formulated a primary research question, "What is the dento-skeletal effect of elastodontic devices on the saggittal plane in mixed dentition patients?" The search was conducted on 13 May 2024, using the Scopus, Web of Science, Embase, and PubMed databases.The search strategy is reflected in Table 1.

286
The studies were included if they met the following criteria, reported according to the PICO format: studies involving growing human subjects in the mixed dentition period (intervention); studies evaluating the treatment effects of elastodontic devices (intervention); studies comparing before and after treatment outcomes with elastodontic devices against other functional appliances or untreated patients (comparison); and studies assessing dental and/or skeletal outcomes using teleradiographic data (outcomes).
The inclusion criteria were as follows: Retrospective and prospective studies The exclusion criteria were: • Patients with permanent or full deciduous dentition

• Studies without radiographic records •
Review studies There were no limitations to the publication year or language.Duplicated records were removed using Zotero and then verified manually.Subsequently, two reviewers (AV and CSF) independently evaluated and selected valid studies based on titles and abstracts.
After the full-text assessment, the studies to be included in the review were selected.In case of disagreement, a third reviewer (RU) resolved the issue.
For each study, we collected the following information: first author, year of publication, setting and country, study design, sample characteristics (sex, age), sample size calculation (yes/no), type of malocclusion, intervention (device and wear instructions), control group type, compliance, follow-up, and cephalometric measurements.

Results
The initial search yielded a total of 1662 results: 504 from Scopus, 286 from PubMed, 426 from Embase, and 446 from Web of Science.After removing duplicates, 726 articles remained.Subsequently, after reading the title and abstract, 83 articles underwent full-text evaluation.Finally, after a thorough assessment, 16 articles met the inclusion criteria and were included in the review.The process of literature search and selection is illustrated in a flow diagram presented in Figure 1.

Study Characteristics
The study characteristics, such as author, year, setting, country, study design, and conclusions, are outlined in Table 2.
According to the study design, 12 studies were retrospective [12,[16][17][18][19][21][22][23][24][25]27,28], while 4 were prospective [20,26,29,30].Most of these studies (n = 14) included a control group for comparison [12,16,17,[19][20][21][22][23][24][25][27][28][29][30].Occlus-o-Guide ® , FR-2, TB increase in Mb length FR-2 and TB are more effective in increasing the Mb length The reduction in the ANB angle was similar in the three groups, but the increase in the SNB angle was significant only for FR-2 and TB Occlus-o-Guide ® , FR-2, and TB produce the following: Reduction in OVJ and OVB in relation to the control group The reduction produced by TB was significant compared to that for the other two devices The IMPA angle increased more in the O-o-G ® group The esthetic analysis shows the following: TB group: More reduction in facial convexity More reduction in the thickness of LL O-o-G ® group: More retrusion of UL followed by that in the TB group FR-2 group: Increase in the thickness of the UL compared to the control group

Inchingolo AD et al. (2022) [18] Italy Retrospective Study
The AMCOP ® Integral with a flat mastication plane is sufficient to correct mild hyperdivergency The AMCOP ® Open is more indicated in severe hyperdivergent.This device also contributes to the functional re-education of the tongue The AMCOP ® SC allows the correction of class II dysmorphism favoring a mandibular advancement The long-term stability of the results obtained is still to be evaluated The sample characteristics are detailed in Table 3.The sample size was estimated in six of the studies [19,20,22,26,27,30].Across the 16 studies, there were a total of 345 participants in the elastometric device group, comprising 142 males and 148 females; sex information was not reported for 55 patients.The mean age was provided in 15 studies, with a total mean age of 8.48 years.The control group comprised untreated patients in six publications [12,16,20,21,23,28], patients treated with another type of appliance in six studies [19,22,24,25,27,30], and both untreated and treated patients in two trials [17,29].Ciftci et al. and Ichingolo et al. did not include a control group [18,26].
A statistically significant reduction in maxillary protrusion, indicated by the SNA angle, was observed in only two studies [21,25].

Elastodontic Appliances vs. Other Functional Appliances
Neither Coban et al. [27] nor Madian et al. [30] found significant differences between the use of myobrace and twin-block appliances.In contrast, Johnson et al. reported statistically significant improvements with twin-block appliances in parameters such as Ar-Gn, OVB, and SN-Go-Gn compared to myobrace appliances [29].
Additionally, Galuccio et al. [17] observed a greater reduction in OVJ and OVB in patients treated with twin-block appliances compared to those using PMA Occlus-o-Guides.Furthermore, Yang et al. noted a greater increase in SNB in patients treated with myofunctional preformed appliances compared to conventional early orthodontic appliances [24].Similarly, Zhang et al. found that T4K showed better results than the Hyrax appliance, particularly in SNA, SNB, and Go-Me [25].Elastodontic Appliances vs. Untreated Patients (Control) In the study by Ciavarella et al. [16], a significant increase in mandibular size (Co-Gn) was observed in the PMA AMCOP group compared to the control group (p = 0.0173).However, the study by Patano et al. [21] found no significant changes in Co-Me (p = 0.102) using the same device.Galuccio et al. [17] observed a significant increase in the Ar-Pg distance when comparing the use of PMA Occlus-o-Guide to the control group (p = 0.004).Additionally, Johnson et al. reported significant changes in both Go-Me (p = 0.005) and Ar-Gn (p < 0.001) with myobrace use [29].
Only Galuccio's study [17] revealed a significant difference in the SNA angle when comparing the use of PMA Occlus-o-Guide with controls (p = 0.017), indicating a reduction in this angle in treated patients.Similarly, Johnson's study [29] found significant differences in SNB when comparing the myobrace with controls (p = 0.017).A smaller ANB was observed in the treatment groups of Patano [21] and Galuccio [17], suggesting mandibular advancement.
Regarding dental values, the reduction in OVJ was significantly greater in several studies [17,21,28,29], as was the reduction in overbite [17,21], when using elastomeric devices compared to the control.

Discussion
The literature resulting from this scoping review indicates that elastodontic devices, when used in growing patients with mixed dentition and mild-to-moderate sagittal issues, can facilitate partial or complete resolution of Class II malocclusions.These devices feature vestibular and lingual flanges with a central area for the teeth, which may have indentations, act as a positioner, or remain free to avoid constriction and orthodontic movement.The vestibular flanges function as lip bumpers and stimulate the bone proprioceptively, activating both arches in the vertical, transverse, sagittal, and torsional planes.The upper and lower planes can be positioned to promote mandibular advancement, while the occlusal plane can be adjusted to manage vertical dimension and tooth eruption.For atypical swallowing, a ramp and button on the lingual flange guide the tongue to the palate, aiding functional rehabilitation [8].Similar to other functional orthodontic therapies, elastodontic devices induce a series of changes by stimulating muscle activity, which subsequently leads to skeletal and occlusal modifications [31].This is supported by the results of the articles included in this scoping review, where a statistically significant increase in the SNB angle was observed in 13 out of 15 studies on Class II patients [12,[17][18][19][20][21][23][24][25][26][27][28][29][30], with the SNB angle varying from +0.61 • [27] to +2.82 • [30].Furthermore, a statistically significant reduction in OVJ was observed in 10 studies [12,[17][18][19][20][21][26][27][28][29], ranging from −2.1 mm [21] to −4.58 mm [26].Additionally, a significant decrease in the ANB angle, indicating mandibular advancement or at least a forward repositioning of the mandible, was found in 11 articles [12,[17][18][19][20][21]23,26,[28][29][30], with values ranging from −0.38 [27] to −2.42 [30].These changes impacted not only the positional appearance of the mandibularjaw and dentoalveolar complex but also the size of the mandible itself, with a noticeable longitudinal increase observed [16,17,21,23,25,26,28,29].
Although limited, an impact on the correction of facial divergence was also noted, yielding discrepant results.Some studies reported a reduction in vertical dimensions [18,19], while others observed an increase [29].In most of the included studies, this parameter remained unaffected or exhibited statistically insignificant changes [16,17,21,23,24,[26][27][28]30].These findings reflect a substantial divergence of opinions in the literature.Some authors suggest that elastodontic appliances maintain unchanged lower facial height and facial proportions [32], whereas others report an increase in these measurements [33].
Only one study that evaluated the effect of elastodontic devices in Class III patients was retrieved [22].Rosinvalle et al. found an increase in SNA, ANB, and OVJ and a decrease in SNB.These changes suggest that these devices can be used to successfully resolve anterior crossbite; however, the existing literature on this topic is insufficient.More studies are needed to clarify their use in these cases [22].
Comparing the results of our study with those of other articles reveals intriguing insights into the effectiveness of elastodontic devices relative to more traditional functional appliances.Multiple systematic reviews corroborate our study's findings, indicating that elastodontic appliances (EAs) are more effective than no treatment in reducing overjet (OVJ), overbite (OVB), and mandibular crowding, as well as in establishing a Class I canine relationship.However, when compared to conventional functional appliances, EAs demonstrate lower efficacy in eliciting dental, skeletal, and soft tissue changes despite their cost-effectiveness [33][34][35].
A plausible explanation for the difference in mandibular skeletal effects between the two families of functional devices may be attributed to the material consistency.The high elasticity of elastodontic appliances (EAs) might make it challenging for young patients to maintain a protrusive mandibular position with the incisors in an edge-to-edge relationship [36].
The dentoalveolar and skeletal outcomes of EAs are contingent upon patient compliance.Adherence to instructions for wearing a removable appliance has been directly correlated with the treatment outcomes achieved [37].Although the majority of studies recommend a protocol of 1 to 4 h of daily wear plus all night [12,16,[18][19][20][21][22][23]25,26,29,30], few studies provide detailed information on whether the patients in their samples adhered to this therapeutic regimen [12,[16][17][18][19][20][21][22][23][24]27,28].Consequently, more rigorous studies are needed to monitor appliance usage accurately to determine patient compliance levels.Ultimately, EAs are designed to provide a combined effect, including guidance of tooth development, training of muscle function, and comprehensive early intervention [23].They have proven effective in treating Class II mixed dentition patients with deleterious oral habits, such as atypical swallowing and altered lip strength [38].The literature suggests that the most suitable period for this type of treatment is during the mixed dentition phase.Therefore, these devices can be effectively used for interceptive orthodontics in growing patients, particularly when the patient's functional patterns are not optimal for harmonious maxillary base growth.
It is important to acknowledge that elastodontic devices cannot replace established orthopedic orthodontic treatments that have been validated by the literature.However, in cases involving growing patients with altered functions, elastodontic devices can serve as a valid alternative and an additional tool for orthodontists.These devices can support and guide growth by refunctionalizing the patient, thus achieving stable results.Therefore, case selection is crucial for the successful application of these devices.
While this scoping review includes a substantial number of studies, it has limitations that necessitate cautious interpretation of the results.Firstly, an analysis of the methodological quality of the included studies was not conducted.Second, the chemical and physical properties of the materials used were not detailed, and no structural differentiation of the various types of elastodontic appliances was made.Thirdly, the current literature is insufficient to deduce the effect of these devices in Class III patients.Fourth, the retrospective nature of the included studies is a limitation stemming from the inherent challenges in designing prospective studies involving the treatment of growing patients.Additionally, the analyzed studies varied in their comparison parameters for the control group, with some articles using other functional therapies and others using untreated patients.More prospective, randomized clinical studies are recommended to explore the efficacy of elastodontic appliances compared to untreated control groups and control groups treated with functional appliances, which are well established and widely supported by scientific evidence.

Conclusions
Treatment with elastodontic appliances shows significant improvements in various cephalometric and dentoalveolar parameters, particularly ANB, SNB, and OVJ, indicating mandibular advancement or at least a forward repositioning of the mandible.Included studies suggest that these devices can be effective in correcting skeletal and dental relationships.However, the variability in the results underscores the need for further research to confirm these findings.
Additionally, the advantages of EAs over traditional functional appliances are not entirely clear and warrant more detailed evaluation.

Table 1 .
Search strategy for Scopus, Web of Science, Embase, and PubMed.

Table 2 .
Characteristics of included studies.

Table 3 .
Sample and treatment characteristics.