Temporomandibular joint disorders (TMDs) are a group of neuromuscular and musculoskeletal disorders that includes a variety of clinical manifestations involving the temporomandibular joints (TMJs), masticatory muscles, and associated tissues or structures[1]. Associated symptoms include joint pain, opening restriction, and displacement in mandibular movement, often accompanied by toothaches, headaches, and sounds such as clicking[2]. TMD can occur at any age, either congenitally or acquired, and symptoms and signs can worsen with age[3].

Young age is associated with a higher risk of TMD, especially due to anatomical and physiological differences in TMJs[4]. In addition, the adaptive capacity of the mandibular condyle to mechanical stimulation is relatively low in children compared with adults[5]. TMDs can lead to psychological distress as well as chronic fatigue syndrome, difficulties in forming social relationships, and recurring sick days or school absences[6]. In addition, it can affect oral and maxillofacial growth and development, as well as quality of life[7]. Causes of TMD in children and adolescents include trauma, occlusal relationships such as open bite and anterior crossbite, oral habits such as grinding and clenching, and a number of systemic diseases including arthritis[8]. Therefore, TMD in children and adolescents is a multifactorial disease, complicating the establishment of an exact etiology[9].

The diagnostic criteria for TMDs have been evolving, starting with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) published in 1992 and continuing with the new Diagnostic Criteria for TMD (DC/TMD) published in 2014[3]. However, similar to the RDC/TMD, the DC/TMD was established for adults; unlike adults, it has not been validated fully in children and adolescents[10]. In addition, indirect interference from caregivers of young children can bias the clinical assessment, resulting in low reliability[11]. Furthermore, the prevalence of TMDs in children and adolescents is based largely on symptoms and signs, associated risk factors, or self-reported pain rather than an exact diagnosis[12]. Consequently, the reported prevalence of TMDs in children and adolescents, as usually assessed at a specific period, varies widely in studies, ranging from 7% to 77.7%[6,13-15].

Therefore, we aimed to analyze the trends in diagnosis and treatment of TMDs in children and adolescents by age over the past 10 years based on data from two institutions using a different approach from previous studies. Knowledge and experience in diagnosing and treating TMD-related pain in children and adolescents are still lacking, and their importance remains underestimated[16]. Through this study, we try to increase interest in the diagnosis and treatment of TMDs in children and adolescents and provide a basis for future studies.

TMDs are representative musculoskeletal disorders affecting the oral and maxillofacial regions and one of the most common causes of nonodontogenic pain[18]. The association between gender and the prevalence of TMDs varies in several studies[19-21]. However, in the present study, there were 1.2-fold and 1.5-fold more females than males in the HIRA and JBNU data, respectively. The diagnosis rate tended to increase with age, with the largest increase in the 15 - 19 year group. This result is similar to a study by Rongo et al.[12] in which the prevalence of TMDs increased with age from childhood to adolescence, especially in females. Late adolescents may experience higher pressure from friendships and academic responsibilities than younger patients. Transitioning away from the family and to the smaller community of school also can place them in stressful environments. Such psychosocial factors contribute to the onset of TMDs and the persistence of TMD-related pain[22,23]. Furthermore, in general, females have higher sensitivity to stimuli and lower thresholds[24]. In addition, females experience more intense, numerous, and frequent physical symptoms than males, and psychological factors such as depression are more prevalent during puberty[25]. Hormones in pubescent females may play a role in the pathology of TMDs[26]. Based on these results, pediatric dentists should notice that population demographics and socio-environmental factors can influence the occurrence of TMDs.

In the HIRA data, the diagnosis rate of TMDs has increased consistently every year since 2011, both for subjects under and over 20 years of age. Yang and Kim[27] also showed an increasing trend in the diagnosis rate of TMDs when analyzed using data from HIRA between 2003 and 2005. Firstly, advancements in medical technology may have enhanced the ability to detect and diagnose TMDs. In addition, psychological factors are considered one cause of TMDs, and the recent increase in anxiety and depression may have influenced the incidence of TMDs[13,28].

However, over the 10-year period, only 0.8% of the total population under 20 years of age was diagnosed and treated with TMDs yet. This is significantly lower than the prevalence of TMDs found in a systemic review by Velesan et al.[29], who reported a diagnosis rate of 11% in children and adolescents. Kim et al.[30] also reported a prevalence of TMD-related symptoms such as pain, clicking sound, and limited mouth opening as greater than 3%. In addition, Macfarlane et al.[31] reported that approximately 60 - 70% of the population has at least one TMD symptom, although only 5% received treatment. Treatment is based on the clinician’s judgment or patient perception of the need for treatment; however, a lack of public awareness and understanding of TMDs remains[32,33]. According to Bakke et al.[34], less than 1% of younger children are aware of the need for treatment. From this perspective, children are less likely than adults to seek treatment because treatment decisions are typically made by their caregivers rather than themselves because they are not fully cognitively developed. It is important to increase the recognition of symptoms of TMD among children, their families, and caregivers through even more active public education and encourage them to seek dental care for diagnosis.

Specifically, according to the JBNU data, only 0.2% of patients were diagnosed in the department of pediatric dentistry when analyzed based on diagnostic departments within the same population as the present study. This indicates that children and adolescents are rarely seen for diagnosis and treatment despite having symptoms of TMDs, especially in pediatric dentistry. Also, it implies insufficient detection of symptoms associated with TMDs at an early stage by pediatric dentists. Therefore, for early and accurate detection, we should include simple examinations related to TMDs such as palpation of the TMJ and masseter muscles and the range and path of mouth opening during daily check-ups[35]. In addition to examinations, it is also essential to assess parafunction and pain or discomfort around the TMJ and associated muscles thorough routine, brief questionnaires. Then, we should consult TMD-related specialists at an appropriate time if necessary. To naturally carry out this series of processes, the importance of education on TMD in pediatric dentistry specialization courses should be emphasized more than ever before.

The K07.6 subgroups were investigated further using JBNU data. Overall, both K07.60 and K07.66 were most prevalent in all ages. However, K07.66 was more prevalent in subjects under 10 years of age, and K07.60 was more prevalent in individuals over 10 years of age. Secondary mandibular growth spurts occur between 10 and 15 years of age, and cortical bone begins to form around the condyle between 12 and 14 years of age[36,37]. The timing of these events is considered responsible for the increase in pain in subjects over 10 years of age, with more frequent pain being associated with the temporomandibular joint itself rather than the muscles. In addition, differences in awareness based on age and limitations in clinical and radiologic examination may have contributed to differences in diagnosis. Therefore, it is important to establish an age-appropriate diagnostic protocol for TMDs prior to treatment. In patients over 10 years of age, a more proactive approach to panoramic radiography, cone-beam computed tomography, and arthrography of TMJ is recommended for a clear diagnosis of TMDs.

Combination treatments are generally accepted as more effective than single treatments and were 1.6- fold more prevalent in the present study. In addition, the treatment rate of occlusal appliances was gradually increased by age. Although occlusal appliance therapy is a simple, effective, and non-invasive method, it may interfere with the eruption of primary and permanent teeth[38]. The therapy also requires caution when used for growing children because the tooth changes during this period require frequent refabrication of the appliance[14]. Therefore, occlusal appliance therapy is considered one of the most commonly used treatments in the late mixed dentition and early permanent dentition when tooth eruption is almost complete[39]. Also, its long-term efficacy in late adolescents has already been proven[40]. However, unlike occlusal appliance therapy, both physical therapy and medication were actively used over 5 years old, and their effectiveness has been demonstrated in several studies[41,42]. In addition to prescription items, various home care methods are recommended, which are considered crucial for treatment[43]. For patients under 10 years old, treatment such as physical therapy, muscle training, and hot packs is recommended over appliance usage. In conclusion, we should consider the tendency for diagnosis criteria and treatment methods to vary according to age. Then, appropriate treatment should follow accordingly based on the diagnosis by using various radiographic results and clinical examinations.

Diagnostic criteria for TMDs are still evolving, and differences may exist in diagnosis between examiners and time periods. The diagnosis rate using the KCD is limited from previous studies because it involves multiple examiners and may include provisional diagnoses for prescription. Also, irreversible treatments were excluded in this study because reversible treatments are preferred for TMDs in children and adolescents[1]. However, the HIRA data cover a long period of 10 years and the entire country rather than a limited region. In addition, the JBNU data allowed treatment trends to be examined with a diagnosis rate, which may be a new approach to TMD research in pediatric dentistry. Notably, non-insurance items such as orthodontic treatment were examined in the present study using JBNU data, unlike in the study by Yang et al.[27] which used only HIRA data. In future studies, the overall trend of reversible and irreversible treatments as well as the detailed analysis of each treatment should be analyzed. In addition, more research with evidence-based data should be conducted on the prevalence and treatment of children with primary or mixed dentition with TMD-related pain.

In the present study, the trends of TMDs in children and adolescents over the last 10 years were analyzed using data from HIRA and JBNU. The diagnosis rate and treatment of TMDs in children and adolescents have been increasing but remain relatively low compared with the clinical symptoms and signs due to the characteristics associated with young age. Consequently, pediatric dentists should recognize clinical symptoms of TMDs and diagnose and treat them promptly to prevent progression to pain. In addition, additional specific procedures for diagnosing TMDs should be performed during daily routine examinations. Therefore, pediatric dentists should have a clear understanding of the symptoms associated with TMDs for early detection in children and adolescents and an appropriate time for consulting with specialists. Furthermore, continued research and efforts to establish definitions, diagnoses, and treatment standards for TMDs in children and adolescents are necessary.