Observational Analytic Study on Craniofacial Growth Changes in Developing Skeletal Class II Malocclusion with a Retrognathic Mandible Patients Using Myobrace

Abstract

Objectives

Myofunctional appliances have been used for correction of developing craniofacial. One of the frequently used is Myobrace. This study aims to assess the effects of the Myobrace appliance on craniofacial growth modifications in developing patients with skeletal class II malocclusion.

Materials and Methods

The research subjects totaled 11 children with predetermined criteria. Subjects were all patients who were being treated with Myobrace (prefabricated myofunctional appliance, Myofunctional Research Co., Australia) at orthodontic clinic of the Hasanuddin University Dental and Oral Hospital. Lateral cephalograms were taken for all patients before and after treatment (4 months later). The effects of the appliances on the craniofacial growth were assessed using five linear measurements (anterior craniofacial height [N-Me], posterior craniofacial height [S-Go], cranial base length [S-N], maxillary length [PNS-A], and mandibular length [Go-Pog]) before and after treatment.

Statistical Analysis

The normality test for data utilized the Shapiro–Wilk test to ascertain the analytical applicability of the standard data distribution. The paired samples t-test was used to assess different parameters between before and after treatment. The threshold for significance was at p-value of < 0.05. Data were analyzed via IBM SPSS for Windows.

Result

It was found that there was a significant change in posterior craniofacial height (S-Go), maxillary length (PNS-A), and mandibular length (Go-Pog), relationship of the mandible relative to the cranial base (SNB) values before and after treatment, and also the ANB values before and after treatment of 2.63 and 1.9 degrees, respectively. There was no significant change in anterior craniofacial height (N-Me) and cranial base length (S-N).

Conclusion

Myofunctional treatment with Myobrace appliance can help overcome class II skeletal malocclusion with retrognathic mandible during the growth period and help craniofacial growth by improving tongue position, breathing, correcting malocclusion, improving orofacial muscle function, and facial development.

Keywords

craniofacial growth - Myobrace - myofunctional - retrognathic mandible - skeletal class II malocclusion

Introduction

Skeletal class II malocclusion is a prevalent dentofacial abnormality characterized by a retrusive mandible and a convex facial profile, affecting a significant portion of the population.[1] This condition is often associated with both dental and skeletal deviations, leading to functional and aesthetic concerns. Skeletal class II malocclusion is regarded as one of the most prevailing dentofacial abnormalities, which has been found to affect approximately one-third of the population.[2] Class II malocclusion affects approximately 19% of the global population, with variations between 15 and 30% depending on the demographic group.[3]

This malocclusion type is particularly common in orthodontic practices due to its noticeable impact on facial aesthetics and function, prompting a variety of treatment approaches tailored to the patient's age and specific dental-skeletal characteristics. The following sections delve into the prevalence, characteristics, and treatment strategies for class II malocclusion.[4]

The importance of recognizing and managing malocclusion is critical during the growth and developmental stages of a child, as malocclusion has a profound impact on important dental-maxillofacial functions, facial aesthetics, and the overall psychosocial well-being of the individual.[5] Oral myofunctional therapy has been described as an early intervention for dysfunction in the facial and oral muscles to improve orofacial processes, such as chewing and swallowing, while facilitating nasal breathing.[6]

Activity of maxillofacial muscles is vital for normal craniofacial growth, influencing both the morphology and functional aspects of the face. Their contractions during early development are crucial for ensuring proper formation and alignment of craniofacial structures.[7] The function of masticatory muscles is closely tied to the stresses they exert on the jawbones. This stress can lead to bone remodeling, which is essential for proper craniofacial development. According to Wolff's law, bone structure is influenced by muscle thickness, indicating that variations in muscle size and activity can significantly impact craniofacial morphology. The thickness of masticatory muscles, such as the masseter, has been shown to correlate with craniofacial morphology.[8] For example, individuals with thicker masseter muscles tend to exhibit different facial structures compared with those with thinner muscles. Specifically, thicker muscles are associated with a greater bizygomatic arch width, indicating a direct influence on facial width and overall shape.[8] [9]

Myofunctional appliances in orthodontics are specialized appliances designed to correct malocclusion and improve orofacial muscle function. These appliances, such as Myobrace by Myofunctional Research Co., are used to address issues such as improper jaw alignment, poor oral habits, correct oral dysfunction, and muscle dysfunction by encouraging proper muscle activity and alignment, thus promoting normal jaw growth, aligning teeth, and improving facial development.[10] [11]

The Myobrace appliance is particularly effective in cases where there is a need for dental arch expansion and correction of class II division I malocclusion. However, its effectiveness may be limited in cases with high-angle maxillary protrusion or severe mandibular retrusion, emphasizing the importance of patient-specific assessments.[12]

Myobrace stretches the muscles of the oral complex (the superficial masseter, medial pterygoid, and inferior head of the lateral pterygoid) that protrude the mandible.[13] [14]

In a case study, the Myobrace demonstrated favorable results in enhancing the facial profile of a patient with class II division 1 malocclusion, suggesting its potential as a simple and effective treatment option when patient compliance is high.[10]

While the Myobrace is effective, other functional appliances like the Twin Block and Bionator are also widely used for treating class II malocclusions. The Twin Block, for instance, is noted for its ability to redirect mandibular growth and improve facial aesthetics, often resulting in more pronounced skeletal changes compared with Myobrace.[15] [16]

While the Myobrace is a valuable tool in the orthodontic treatment of class II malocclusion, it is essential to consider the individual characteristics of each patient to ensure optimal outcomes. The appliance's effectiveness can vary based on the severity of the malocclusion and the specific skeletal discrepancies present. Therefore, the effectiveness of Myobrace and other functional appliances is heavily dependent on patient compliance and the specific clinical situation, emphasizing the need for personalized treatment approaches.[17]

Clinical modification of bone growth that includes the craniofacial complex is very interesting in the field of orthodontics. In some literature, there are five measurements (anterior craniofacial height [Na-Me], posterior craniofacial height [S-Go], cranial base length [S-Na], maxillary length [PNS-A], mandibular length [Go-Pog]) that can be assessed to provide an overall picture of craniofacial measurements ([Fig 1]).[18]

Fig. 1 Landmark points used in cephalometric analysis for assessing anterior craniofacial height (N-Me), posterior craniofacial height (S-Go), craniofacial base length (S-N), maxillary length (PNS-A), and mandibular length (Go-Pog).

From the previous explanation, after knowing the function and working mechanism of Myobrace and its influence on children's growth patterns, the author tried to find out the influence of using the Myobrace device on changes in craniofacial size in children with a class II skeletal diagnosis. This is the basis for researchers to conduct research on craniofacial growth changes in developing skeletal class II patients using Myobrace.

Materials and Methods

Study Design and Population

The research methodology used is observational analytic using a cross-sectional study design. Research was conducted at the Orthodontic Polyclinic of Hasanuddin University Dental and Oral Hospital. This prospective research has received approval from the Health Research Ethics Committee of the Dental and Oral Hospital, FKG UNHAS (011/KEPK FKG-RSGMP UH/EE/X/2024). Participants provided permission by completing a consent form. This research started in August 2024 and concluded in December 2024.

Inclusion Criteria

The sample technique used in this research is purposive sampling with inclusion criteria are patients who have used the Myobrace (prefabricated functional appliance, Myofunctional Research Co., Australia) stage I for a minimum of 4 months. Patients adhered to the manufacturer's recommendations by using their appliances at least 2 hours every day and a maximum of overnight and consistently do myofunctional exercises three times daily. Patients aged 7 to 12 years, without anomalies in hard and soft tissues (tumors or cancer), and with no prior orthodontic treatment

Exclusion Criteria

The criteria for exclusion are patients with an overjet of < 7 mm who do not consistently use the Myobrace. Craniofacial growth assessed in five dimension (N-Me, S-Go, S-NA, PNS-A, Go-Pog) were summed to give an overall representation of craniofacial size.

Data Collection

The participants in this research were patients receiving myofunctional treatment at the Orthodontic Polyclinic of the Dental and Oral Hospital of Hasanuddin University. Throughout the research period, 11 children patient records, including lateral cephalometric film, age, gender, ethnic, diagnosis, treatment plan, and treatment duration, were collected.

The first step that the researcher did was to explain the research objectives and ask for the informed consent. After that, the researcher performed cephalometric tracing manually to obtain the desired variable values using a previously calibrated cephalogram tool (anterior craniofacial height [N-Me], posterior craniofacial height [S-Go], cranial base length [S-N], maxillary length [PNS-A], and mandibular length [Go-Pog]), and SNA, SNB, and ANB angles.

Statistical Analysis

Data analysis was performed using the SPSS program, employing the paired t-test and Shapiro–Wilk test for normality assessment. The sample technique used in this research is total sampling.

Result

Respondent characteristics offer a comprehensive description of the respondents who are the focus of the study. There were 5 males and 6 females. All of the study population were not older than 12 years of age. The sample is divided into two ethnicities, nine respondents from the Bugis-Makassar and two from the Toraja ([Tables 1]).

Table 1 Sample distribution of gender, age, and ethnicity

No.	Gender	Total
1.	Male	5 Person
2.	Female	6 Person
	Age
1.	7 years old	2 Person
2.	8 years old	6 Person
3.	9 years old	1 Person
4.	10 years old	1 Person
5.	11 years old	1 Person
Ethnicity
1.	Bugis-Makassar	9 Person
2.	Toraja	2 Person

This study involved measuring craniofacial changes across five dimensions: anterior craniofacial height (N-Me), posterior craniofacial height (S-Go), cranial base length (S-N), maxillary length (PNS-A), and mandibular length (Go-Pog) from the cephalograms of patients using the prefabricated myofunctional appliance Myobrace to assess craniofacial development before and after treatment. The Shapiro–Wilk normality test was conducted, confirming that the data are normally distributed.

[Tables 2] presents the results of statistical analyses on the measurement of posterior craniofacial height (S-Go), which yielded a p-value = 0.027, indicating a significant change in craniofacial growth during orthodontic treatment of children in the growth and development phase using Myobrace, as the p-value was < 0.05. The anterior craniofacial height (N-Me), revealing a p-value of > 0.05, indicated no significant change in craniofacial development. The posterior craniofacial height (S-Go) yielded a p-value = 0.027.

Table 2 Measurement of craniofacial changes

Variable	n	Before treatment (T1) ( ± SD)	After treatment (T2) ( ± SD)	Significance
N-Me	11	110.45 ± 5.47	112.00 ± 6.10	0.115
S-Go	11	69.73 ± 3.53	71.59 ± 3.68	0.020[a]
S-N	11	67.55 ± 3.39	68.00 ± 3.73	0.127
PNS-A	11	44.09 ± 3.76	45.05 ± 4.42	0.008[a]
Go-Pog	11	69.68 ± 3.93	71.45 ± 4.78	0.027[a]

Abbreviation: SD, standard deviation.

Note: Paired t-test. n: Quantity of samples; N-Me, S-Go, S-N, PNS-A, Go-Pog; Mean ( mm).

^a Statistically significant (p-value < 0.05).

The statistical analysis of maxillary length (PNS-A) and mandibular length (Go-Pog), with a p-value < 0.05, indicated significant growth alterations. In contrast, the measurements of craniofacial base length (S-N) yielded a p-value = 0.127, indicating a nonsignificant change in growth, as this p-value was > 0.05.

From the results of the cephalometric examination using Steiner analysis, it was found that there were significant changes between the SNB values before and after treatment and also the ANB values before and after treatment of 2.63 and 1.9 degrees, respectively ([Table 3]).

Table 3 Skeletal measurements: SNA (relationship of the maxilla relative to the cranial base), SNB (relationship of the mandible relative to the cranial base), ANB (skeletal relationship between the maxilla and mandible)

Variable	n	Before treatment (T1) ( ± SD)	After treatment (T2) ( ± SD)	Significance
SNA	11	81.90 ± 4.08	82.36 ± 3.52	0.096
SNB	11	76.72 ± 3.25	79.09 ± 2.42	0.000[a]
ANB	11	5.18 ± 1.94	3.27 ± 2.00	0.000[a]

Abbreviation: SD, standard deviation.

Note: Paired t-test. n: Quantity of samples; SNA, SNB, ANB; Mean ( mm).

^a Statistically significant (p-value < 0.05).

Discussion

Craniofacial development refers to the formation and development of the cranium and facial tissues from early embryonic life to maturity. The formation of hard tissues (bones and teeth) and soft tissues (such as muscles, skin, and ligaments) is influenced by multiple genetic, biological, and environmental factors, which is why this process is complex. This development is crucial for the stomatognathic system, which is responsible for the function of the teeth and their supporting structures and is essential for speech, swallowing, and inhaling. In addition to determining the contour of the face, it also affects those functions. A thorough knowledge of dentocraniofacial development is required for orthodontic therapy and the management of malocclusion issues (irregular tooth and jaw position). The appropriate approach may involve using orthodontic myofunctional appliances that can solve functional issues, such as respiratory disorders, measure tooth position, or promote improved development of the lower mandible.[19]

Myobrace works on the craniofacial system of muscles to a physiological load of bones and stimulates growth and development of their structures including alignment of teeth. Consequently, the facial and masticatory muscles operate well, and the forces between the cheek and tongue achieve balance owing to the correct tongue position during both function and rest. The appliances induce significant alterations that were measured in linear metrics, which indicated simultaneous changes in size.[20]

Some previous research by Usumez et al, Johnson et al, Habumugisha et al, and Madian and Elfouly have observed that patients treated with Myobrace appliance showed significant changes in anterior and posterior craniofacial height, maxillary length, and mandibular growth.[6] [20] [21] [22]

These studies are in line with this study, the results of statistical tests show that there are significant changes in the dimensions of posterior craniofacial height (S-Go), maxillary length (PNS-A), and mandibular length (Go-Pog) after treatment using Myobrace. These results indicate that the use of myofunctional appliances contributes to modulating craniofacial growth. Similar to the study by Chuang et al that reported significant craniofacial changes including craniofacial height, craniofacial base length, and the lengths of the maxilla and mandible, in patients who received myofunctional treatment.[23]

However, in contrast to anterior craniofacial height (N-Me) and cranial base length (S-N), this study showed no significance. In comparison to previous studies, this may be ascribed to several factors, including variations in the duration of the research and subjects with different sagittal and vertical skeletal discrepancies.

This study also showed significant changes between SNB and ANB values before and after treatment; this shows that myofunctional treatment with Myobrace can help overcome class II skeletal malocclusion during the growth period. This is in accordance with a systematic review study by Rusli et al in 2024, which compared myofunctional treatment between Twin Block and Myobrace. The study concluded that both of these devices can be used as an alternative treatment for class II skeletal malocclusion during the growth period.[15]

Limitation

The main limitation of this study is that the variable of oral bad habits was not included and the limited number of samples used is still small, so the generalization of this research is still less reliable.

Conclusion

Myofunctional treatment with Myobrace appliance can help overcome class II skeletal malocclusion with retrognathic mandible during the growth period and help craniofacial growth by improving tongue position, breathing, correcting malocclusion, improving orofacial muscle function, and facial development.

Conflict of Interest

None declared.

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Publication History

Article published online:
17 October 2025