Association between Clark twin block appliance treatment and social and emotional wellness in children with malocclusion – a cohort study

Abstract

Introduction

Class II malocclusion is common among adolescents and can negatively affect aesthetics, self-esteem, and social interactions. Myofunctional appliances like the Clark twin block aid in correcting jaw discrepancies during growth. Traditional clinical assessments often overlook psychosocial outcomes, which can be captured through patient-reported outcome measures (PROMs) such as the Child Perception Questionnaire (CPQ). This study evaluates the association between Clark twin block appliance therapy and social and emotional wellness in children, addressing a gap in patient-centered orthodontic care in Pakistan.

Methods

This cohort study, approved by the Ethical Review Committee (ERC) and adhering to STROBE guidelines, involved 56 children treated with Clark’s Twin Block appliance at Aga Khan University Hospital. Patients aged 13–17 years at Cervical Vertebral Maturation (CVM) stages 3 or 4, compliant with the appliance, were included; those with anomalies or communication issues were excluded. Pre- and post-treatment social and emotional impacts were assessed using the prevalidated CPQ, administered after the completion of Clark Twin Block appliance treatment. Data analysis via SPSS employed paired t-tests/Wilcoxon tests, with p < 0.05 considered significant.

Results

The study included 56 participants: 27 males (48.2%) and 29 females (51.8%), with median ages of 13 (IQR: 13–14) and 14 years (IQR: 13–15), respectively. A positive association was found between the intervention and improved emotional and social wellness. Emotional wellness scores decreased from a median of 7.5 to 3 (p < 0.001), and social wellness scores from 1.5 to 0 (p < 0.001). Gender-based comparisons showed no significant differences, indicating equal effectiveness for both genders.

Conclusions

Interceptive orthodontic treatment with Clark’s Twin Block is positively associated with social and emotional wellness in children with malocclusion. It reduces distress, frustration, and shyness while boosting confidence in social interactions and school activities. The study emphasizes using PROMs to assess clinical and psychosocial outcomes, promoting patient-centered orthodontic care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40359-025-03953-w.

Introduction

Malocclusion (misalignment of the teeth) is a developmental condition where the teeth in the same arch or the relationship between the upper and lower teeth are not aligned correctly [1]. It is recognized as one of the most prevalent oral health concerns globally, with an estimated prevalence of 56%. [2] In Pakistan, malocclusion is highly prevalent, particularly among adolescents, with an estimated occurrence rate of approximately 57.4%. Among these, Class I malocclusion is the most commonly observed subtype, followed by Class II malocclusion (a condition where the upper teeth and jaw are positioned ahead of the lower teeth), which affects approximately 10.8% of the adolescent population [3]. This high prevalence underscores the significance of malocclusion as a public health concern, influencing both aesthetic and functional aspects of oral health.

The aesthetic dimension of malocclusion connects closely to its psychological and social consequences, particularly among children and adolescents. Facial aesthetics play a pivotal role in shaping the psychological and social experiences of children and adolescents. Untreated malocclusion, particularly Class II, can adversely affect self-perception and social interactions from an early age. Children with dental and facial irregularities often encounter difficulties in peer acceptance [4]. Those perceived as more attractive tend to experience greater social approval and, in some cases, are even viewed as more competent or socially skilled. Conversely, negative remarks about appearance can undermine self-esteem and contribute to psychological distress [5]. The consequences of malocclusion extend beyond aesthetics, encompassing profound psychological, social, and physical implications. These impacts collectively reduce oral health-related quality of life, underscoring the importance of timely intervention and comprehensive management.

Orthodontic treatment plays a pivotal role in correcting jaw discrepancies, particularly in children, for improved facial aesthetics, dental health, and functional effectiveness [6]. Among the various treatment modalities, myofunctional appliances, such as the Clark twin block (a type of orthodontic appliance used to correct jaw misalignment by encouraging the growth of the lower jaw), are crucial in growth modification for adolescents with skeletal malocclusion. These appliances are designed to address jaw discrepancies by guiding facial and dental development during crucial growth periods [7, 8]. Moreover, myofunctional therapy, through exercises and re-education, helps restore proper muscle function and movement patterns of the face and mouth, contributing to both functional and aesthetic improvements [9].

Traditional evaluations of malocclusion have primarily relied on clinical measures such as occlusal indices and cephalometric analysis, which, although valuable for assessing the technical success of orthodontic treatments, often overlook the emotional and social dimensions of the patient’s experience [10]. Since patients are the direct recipients of care, their perspectives on treatment and outcomes should be prioritized. Patient-reported outcome measures (PROMs) address this gap by providing critical insights into the effectiveness and safety of care from the patient’s viewpoint [11]. These measures evaluate the impact of treatment on health, wellness, and quality of life, enabling a comprehensive assessment of outcomes that matter most to patients. In orthodontics, PROMs are particularly significant for capturing changes in functional and aesthetic aspects, as well as the psychosocial effects of treatment, thereby offering a holistic understanding of patient-centered care [12, 13]. This underscores the importance of integrating PROMs into routine orthodontic practice to ensure a more comprehensive and patient-centered evaluation of treatment outcomes.

Orthodontic treatment is often pursued to improve social wellness, making it essential to assess its psychological and quality-of-life impacts, particularly in growing children whose self-esteem and social interactions are closely tied to their appearance and oral health. Currently, orthodontic-specific PROMs are not routinely used in clinical care. Incorporating patient-reported outcome measures (PROMs) allows for a more comprehensive evaluation of the psychosocial effects of orthodontic treatment. To the best of the authors’ knowledge, no study has been conducted in Pakistan to assess the influence of Clark twin block therapy on the quality of life in young children with malocclusion. This study aimed to assess the association between orthodontic treatment and social and emotional wellness among adolescents using PROMs, providing a deeper understanding of the psychosocial benefits of orthodontic intervention. By doing so, it seeks to provide valuable insights into the psychosocial benefits of orthodontic interventions and inform a more patient-centered approach to care.

Materials and methods

This cohort study was conducted following approval from the institution’s Ethical Review Committee (ERC # 2024–10899-32524) and in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines [14]. The data for this cohort study were collected from January to March 2025. Children who had been treated at the Aga Khan University Hospital Orthodontics clinics using the Clark’s Twin Block appliance were identified through orthodontic record files. Patients who had completed their treatment within the past two years and met the inclusion criteria were selected for the study.

Patients aged 13 to 17 years who required treatment with Clark’s twin block appliance were included in the study. The participants were clinically assessed to have a retrognathic profile, indicating a retruded mandibular position. Cephalometrically, they were diagnosed with skeletal Class II malocclusion. The severity of Class II malocclusion in this study was diagnosed using standard cephalometric criteria. Specifically, an ANB angle greater than 4 degrees was considered indicative of Class II malocclusion. Severity was further classified based on the degree of the ANB angle, with higher values indicating more severe skeletal discrepancies. In addition, participants were required to be at Cervical Vertebral Maturation (CVM) stage 3 or 4. CVM stages are six phases (C1-C6) that assess skeletal age from a lateral head X-ray, based on the shape and concavity of the lower borders of the second (C2), third (C3), and fourth (C4) cervical vertebrae, indicating growth spurts in orthodontics, with C1/C2 prepubertal, C3/C4 circumpubertal (peak growth), and C5/C6 postpubertal. Furthermore, only patients demonstrating adequate compliance with the appliance were included in the study. Patient compliance with wearing the Twin Block appliance was assessed through clinical logs. During follow-up visits at the time of treatment, patients self-reported their daily wear time, which was documented in the clinical logs. These records, created during the course of their treatment, were reviewed as part of the data collection process for the study. Patients with dental anomalies, temporomandibular joint disorders, craniofacial syndromes, and those unable to communicate effectively in English were excluded. We included only participants proficient in English to ensure clear communication and accurate responses. Almost all participants were comfortable with English, and all study materials were designed in English. To ensure consistency and prevent misunderstandings, we chose to exclude participants who primarily spoke the local language. This decision was made to avoid any language barriers that could affect the quality of data.

The survey instrument used in this study was the prevalidated Child Perception Questionnaire (CPQ) [15]. The 10-item version of the CPQ used in this study is a pre-validated tool that has been previously used in a similar study. To assess the social and emotional wellness of adolescents undergoing orthodontic treatment, the CPQ was used as a PROM. The use of PROMs in orthodontic research has been well established, with studies like Mousa et al. [16] demonstrating the feasibility and benefits of applying PROMs to assess patient-centered outcomes. Informed assent was obtained from the children, and informed consent was acquired from their parents at the start of the study, including permission to use the collected responses for publication purposes prior to questionnaire distribution. Confidentiality of the data was strictly maintained.

To assess the social and emotional impact of malocclusion, the selected children (56 participants) were administered pre- and post-operative CPQ questionnaires. The sample size of 56 was chosen based on a previous study [15] in this area and practical considerations, as no formal sample size calculation was performed. However, we believe this sample size is adequate to provide meaningful insights based on the study’s design and objectives. The questionnaire comprised ten closed-ended questions, categorized into emotional and social wellness, with each question offering five response alternatives on a 5-point Likert scale: 0 for “never,” 1 for “once or twice,” 2 for “sometimes,” 3 for “often,” and 4 for “every day or almost every day.”

To minimize selection bias, efforts were made to include patients with diverse characteristics, such as gender and socioeconomic status, to ensure a broad representation of the target population. The retrospective nature of the study means that recall bias was an inherent limitation; however, by using standardized records and validated instruments, we reduced the potential impact of this bias on the findings.

Data was imported and analyzed using SPSS for Windows (version 26.0, SPSS Inc., Chicago). Frequencies and proportions were reported for categorical variables. The Shapiro-Wilk test was performed to evaluate the normality of the data. Medians and interquartile ranges (IQR) were reported. The paired t-test and the Wilcoxon signed rank test were employed to compare the pre- and post-treatment values within each of the two domains. A p-value of less than 0.05 at a 95% confidence interval was considered statistically significant.

Results

The study included 56 participants, with a nearly equal distribution of genders: 27 males (48.2%) and 29 females (51.8%) (Table 1). The median age for males was 13 years (IQR: 13–14), while for females, it was 14 years (IQR: 13–15). A positive association was found between the intervention and improved emotional and social wellness. Before treatment, many frequently felt upset, frustrated, and shy due to their teeth or mouth, with 46.4% reporting feeling upset “sometimes,” 42.9% experiencing frustration “sometimes,” and 28.6% feeling shy “every day or almost every day.” Post-treatment, these issues were markedly reduced, with 35.7% feeling happy about their appearance “every day or almost every day,” 71.4% consistently satisfied with their appearance, and 55.4% reporting no feelings of shyness. Social wellness showed significant improvement, with the total social wellness score decreasing from a median of 1.5 (IQR: 0–4) pre-treatment to 0 (IQR: 0–1) post-treatment (p < 0.001), indicating a substantial positive change. Concerns about others’ opinions significantly decreased, with 85.7% no longer worrying about how they were perceived, and confidence in smiling, laughing, and interacting socially greatly improved; 80.4% felt confident to smile and laugh daily, and 66.1% consistently felt happy to engage with peers. Confidence in participating in school activities, such as sports and clubs, improved significantly post-treatment. Additionally, teasing was notably reduced, with 0% of participants reporting teasing after treatment compared to 28.6% before treatment (p < 0.001), showing a complete resolution of this issue. In the emotional wellness domain, all five items demonstrated statistically significant improvement, with test p-values below 0.001 for most items (Table 1). The total emotional wellness score showed a marked improvement from a median of 7.5 (IQR: 6–10) pre-treatment to 3 (IQR: 1–4) post-treatment (p < 0.001) (Table 1). Similarly, in the social wellness domain, all five items showed significant improvement, with p-values ranging from 0.001 to less than 0.001 (Table 1). The total social wellness score decreased significantly from a median of 1.5 (IQR: 0–4) pre-treatment to 0 (IQR: 0–1) post-treatment (p < 0.001) (Table 1). Gender-based comparisons revealed no statistically significant differences in emotional total pre- and post-treatment scores (p = 0.396 and p = 0.927, respectively) or in social total pre- and post-treatment scores (p = 0.198 and p = 0.205, respectively), indicating that the treatment was equally effective for both males and females in improving emotional and social outcomes (Table 2).

Table 1.

The comparison of pre-treatment and post-treatment scores of emotional and social wellness among a sample of Pakistani adolescents (N=56) after Clark’s Twin Block appliance

Questions	Pre-treatment Median (IQR)	Post-treatment Median (IQR)	p-value
Emotional domain
How often had you been upset because of your teeth or mouth?	2 (2, 3)	1 (0, 2)	< 0.001**
How often had you felt frustrated because of your teeth or mouth?	2 (1, 2)	0 (0, 1)	< 0.001**
How often had you been shy because of your teeth or mouth?	2 (1, 4)	1 (0, 1)	< 0.001**
How often had you been concerned about how other people look at your teeth or mouth?	1 (0, 2.75)	0 (0, 0)	< 0.001**
How often had you worried that you won’t be able to do things as others because of your teeth or mouth?	0 (0, 2)	0 (0, 1)	0.003*
Total	7.5 (6, 10)	3 (1, 4)	< 0.001**
Social domain
How often had you tried not to smile or talk with other children because of your teeth or mouth?	0 (0, 1)	0 (0, 0)	0.005*
How often had you not wanted to talk to other children because of your teeth or mouth?	0.5 (0, 2)	0 (0, 1)	0.002*
How often had you had a hard time speaking with friends in school because of your teeth or mouth?	0 (0, 1)	0 (0, 0)	0.001*
How often had you stayed away from other children in school and clubs because of your teeth or mouth?	0 (0, 0)	0 (0, 0)	0.005*
How often had other children teased or called you bad names because of your teeth or mouth?	0 (0, 1)	0 (0, 0)	< 0.001**
Total	1.5 (0, 4)	0 (0, 1)	< 0.001**

Wilcoxon signed rank test, p ≤ 0.05*, p ≤ 0.001**

N 56, IQR Interquartile range

Table 2.

Gender-based comparison of pre-treatment and post-treatment scores of emotional and social wellnesses among a sample of Pakistani adolescents (N=56) after Clark’s Twin Block appliance

Variable	Male Median (IQR)	Female Median (IQR)	p-value
Emotional wellness total pre-treatment	7 (6, 9)	8 (5, 12)	0.396
Emotional wellness total post-treatment	3 (1, 4)	3 (1, 4)	0.927
Social wellness total pre-treatment	1 (0, 4)	2 (0, 6)	0.198
Social wellness total post-treatment	0 (0, 1)	1 (0, 2)	0.205

Mann-Whitney U test, p < 0.05*

N 56, IQR Interquartile range

Discussion

The study assessed the association of social and emotional wellness before and after treatment, using PROMs to capture pre- and post-treatment states concurrently. The results demonstrated significant improvements in social and emotional wellness following treatment with the Clark Twin Block appliance. Notable improvements included reductions in distress, frustration, and shyness, along with increased confidence in social interactions. In the present study, children initially expressed significant concerns regarding their appearance, with many reporting distress (46.4%), frustration (42.9%), or shyness (28.6%) related to their teeth or oral condition. Additionally, they were apprehensive about how they were perceived by others and worried about remarks directed at them, reflecting a diminished quality of life in the emotional domain. Following the intervention, our findings suggest a positive association between Clark twin block treatment and improved quality of life. Nearly all children expressed satisfaction with their appearance post-treatment, with 71.4% indicating a high level of contentment and 55.4% reporting no feelings of shyness. These findings underscore the positive impact of the intervention on all aspects of emotional wellness. Previous studies on the acceptability of functional appliances have highlighted both the benefits and challenges associated with these treatments. Idris et al. [17] found that while patients reported significant discomfort during treatment with functional appliances, they also acknowledged improvements in their overall wellness once the treatment was complete.

Physical appearance is a critical factor in shaping personal identity when social interactions and acceptance become significant concerns. Scheffel et al. [18] highlighted that an unaesthetic appearance can provoke unfavorable social responses, thereby impairing social interactions and psychological wellness, especially in children. These findings align with the present study, which revealed that children with malocclusion often experienced unease while talking, laughing, or engaging with friends due to the unpleasant appearance of their teeth and mouth. Additionally, these children lacked confidence in participating in sports and extracurricular activities. This underscores the broader impact of malocclusion on oral health-related quality of life (OHRQoL), as it significantly influences psychosocial wellness, particularly within the social domain, as concluded by Foster et al. and O’Brien et al. [19, 20]

Our findings on the improvement in social and emotional wellness align with previous systematic reviews, such as Shaadouh et al. [21] which showed that orthodontic treatments significantly boost self-esteem and improve quality of life, particularly in adolescents undergoing functional appliance therapy. In line with Almrayati et al. [22] who evaluated soft tissue changes following Class II correction, our study found significant psychosocial improvements following treatment with the Clark Twin Block, reflecting positive social outcomes related to the treatment’s effectiveness.

Orthodontic treatment has the potential to significantly enhance self-confidence [15]. In the present study, notable progress was observed in social wellness following the intervention. Children reported marked improvements in confidence, with 80.4% expressing daily confidence in smiling and laughing and 66.1% consistently feeling happy to engage with their peers. Additionally, children who had previously exhibited distractibility and difficulty concentrating in school reported becoming more engaged, communicative, and interactive, with self-reported improvements in their academic performance. It is important to note that these improvements were based on self-reported changes, as no objective school performance data were available for analysis. Al Omari et al. [23] revealed a significant association between poor oral OHRQoL and bullying driven by dentofacial traits, advocating for the integration of anti-bullying programs in educational settings. Similarly, Seehra et al. [24] highlighted that the social impairments, often stemming from bullying or teasing related to dental appearance, can adversely affect a child’s wellness. However, their findings also demonstrated that orthodontic treatment can lead to substantial improvements in both social and emotional wellness, aligning with the results of our study.

An important factor to consider is gender, as it may influence the psychosocial outcomes associated with malocclusion and orthodontic treatment. Research has shown that gender differences can significantly affect how individuals perceive their dental appearance, engage in social interactions, and cope with the emotional challenges related to oral health. Foster-Page et al. [19] found that girls had higher mean emotional wellness scores compared to boys. Similarly, Cohen-Carneiro et al. [25] suggested that females may place greater importance on their oral health in relation to their quality of life, making them more sensitive to both positive and negative impacts on their wellness. However, in this study, no statistically significant differences were observed in the total emotional (p = 0.396, p = 0.927) or social scores (p = 0.198, p = 0.205) pre- and post-treatment, indicating that the treatment was equally effective for both males and females in improving emotional and social outcomes.

While this cohort study provides valuable insights into the impact of the Clark Twin Block effect on social and emotional wellness, it is important to recognize the limitations inherent in the study design. Firstly, the purposive sampling method employed restricts the generalizability of the findings to broader populations. Secondly, the retrospective nature of the study precludes establishing a causal relationship between the intervention and observed outcomes. A significant limitation of this study is the retrospective collection of pre-treatment CPQ data, which introduces the potential for recall bias. Participants were asked to recall their condition prior to treatment, which may not accurately reflect their true pre-treatment state. This should be considered when interpreting the findings, as recall bias could influence the validity of the baseline data. Third, the study also lacked objective clinical severity reporting (e.g., overjet measurements or cephalometric analysis), which would have provided more reliable baseline data. Fourth, the lack of a control group limits our ability to attribute the observed psychosocial improvements solely to the orthodontic treatment, as other factors may have influenced the outcomes. Fifth, the lack of baseline data on the severity of malocclusion (such as overjet, ANB, and CVM details), as well as information on the duration of appliance wear and compliance metrics. These factors could potentially confound the psychosocial outcomes and should be considered in future research to provide a more comprehensive understanding of their impact on treatment effects. Additionally, the small sample size (N = 56) may reduce statistical power and limit the generalizability of the findings. Finally, social desirability bias may have influenced participants’ responses on the Patient-Reported Outcome Measures (PROMs), as participants may have provided socially desirable answers regarding their psychosocial wellness. To mitigate this in future research, it may be more effective to collect pre-treatment concerns at the start of treatment. Future studies with larger, more representative samples and a longitudinal design could provide a more robust understanding of the long-term effects of the Clark Twin Block appliance on psychosocial wellness.

OHRQoL measures provide a unique and invaluable perspective on how oral conditions affect an individual’s daily life, offering crucial insights that enable dentists to gain a deeper understanding of their patients’ treatment needs. These measures not only enhance the clinician’s comprehension of treatment outcomes but also allow for a more patient-centered approach by capturing the patient’s perspective. To the best of our knowledge in our region, this may be among the first studies to evaluate the improvements in the social and emotional domains of health following the use of myofunctional appliances, highlighting its significance in both clinical practice and advancing the understanding of psychosocial benefits in orthodontic treatment. The study’s innovative approach and comprehensive evaluation contribute to filling a critical gap in the current literature.

Conclusion

Interceptive orthodontic treatment with myofunctional appliances, such as the Clark Twin Block, is positively associated with the social and emotional wellness of children with malocclusion. The results demonstrated considerable reductions in distress, frustration, and shyness, along with increased confidence in social interactions and school activities. This study highlights the importance of incorporating PROMs to evaluate both clinical outcomes and psychosocial benefits, offering a patient-centered approach to orthodontic care.

Authors’ contributions

R.K: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software; Writing – original draft H.Y: Software; Writing – original draft R.I: Data curation, Methodology; R.H : Supervision, Validation, Statistical analysis and Proof reading of manuscript, Writing - Review & Editing; M.F: Supervision, Validation, Proof reading of manuscript.

Funding

No funding was obtained in the execution of this research.

R.K: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software; Writing – original draft H.Y: Software; Writing – original draft R.I: Data curation, Methodology; R.H: Supervision, Validation, Statistical analysis and Proof reading of manuscript, Writing - Review & Editing; M.F: Supervision, Validation, Proof reading of manuscript.

Data availability

The datasets used and/or analyzed during the present study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This work has been carried out in accordance with the Declaration of Helsinki (2000) of the World Medical Association. This study has been approved by the Ethics Committee of Aga Khan University Hospital (ERC# 2024-10899-32524) with the approval date of 30-Dec-2024. Informed consent was obtained from the parents, and assent was obtained from the children. Both the assent and consent forms were written in English and outlined the purpose of the study, potential risks, and the voluntary nature of participation. The CPQ was self-administered by participants.

Consent for publication

Consent for publication was not required.

Competing interests

The authors declare no competing interests.

Clinical trial number

Not applicable due to the cohort nature of the study.