A rare disease is a disease with a prevalence of < 20,000 people or unknown prevalence because of difficulty in diagnosis, as determined by procedures and standards set by the Ministry of Health and Welfare. In addition to rare diseases, ultra-rare diseases are distinct diseases with diagnostic methods and a prevalence of < 200 people in Korea or diseases without separate disease codes[1]. In addition, chromosomal abnormality diseases present as new chromosomal abnormalities (such as chromosomal deletions and duplications) without specific disease names, and unspecified rare diseases remain undiagnosed despite significant diagnostic efforts and cannot be classified within the Korean Standard Classification of Diseases[1]. According to statistics from the Korea Disease Control and Prevention Agency, as of January 1, 2021, 1,086 rare diseases have been officially announced, with 55,874 rare disease cases reported in Korea in 2021. Among these cases, 3,071 occurred in individuals aged < 20 years. Representative pediatric rare diseases include Crohn’s disease, moyamoya disease, systemic lupus erythematosus, tetralogy of Fallot, and epilepsy[2].

Pediatric patients with rare diseases are at a higher risk of developing oral complications or functional impairments. Because of the abnormal growth of the maxillofacial region or underdeveloped jaws, the prevalence of malocclusion is high, including anterior open bite, crossbite, and high palates[3-5]. In addition, the frequencies of dental developmental anomalies, such as congenital tooth agenesis, enamel hypoplasia, and xerostomia, are higher[6-9]. Patients with intellectual disabilities, executive function disorders, and learning disabilities find it challenging to maintain oral hygiene[10,11], making them more susceptible to dental caries and resulting in a higher prevalence of multiple carious lesions[12-14]. The high incidence of caries leads to increased dental treatment costs, reduced masticatory function caused by the early loss of primary teeth, the development of malocclusion, and decreased patient quality of life[15,16].

The development of oral function and dental health is closely related to a child’s growth and development and is important in improving overall health and quality of life. Despite the critical importance of oral health, pediatric patients with rare diseases often lack information on oral care, and caregivers find it difficult to manage their oral hygiene[17-19]. Therefore, professional oral care and preventive approaches are crucial for these patients. Oral care comprises a medical history review, intraoral examination, and professional dental care, including procedures such as scaling, professional plaque control, fluoride application, tongue coating removal, denture care, and the management of intraoral wounds and stomatitis[20,21]. Early diagnosis of oral diseases through regular management can prevent disease progression, making early intervention essential. However, given the lack of medical and dental information on rare diseases, establishing treatment plans and predicting prognoses remain challenging[8,22].

Before dental treatment, the medical history and relationship between rare diseases and dental issues must be elucidated. Professional consultations are required to assess potential problems, precautions, and medication adjustments during dental treatment. Given the uniqueness of rare diseases, dentists often find it difficult to intervene dentally because they do not understand systemic diseases and face challenges in behavior management[23,24].

Oral diseases tend to be treated later than other physical illnesses[18,25,26]. Given cognitive and motor developmental limitations that accompany these diseases, visits to medical institutions are challenging, placing pediatric patients with rare diseases in a blind spot for dental services.

Despite studies on dental complications and oral hygiene in patients with rare diseases[6,7,17,27], no studies have focused on the specific dental treatment practices for this population in Korea. Thus, this study aimed to investigate the dental treatment experiences of all pediatric patients with rare diseases who visited Yonsei University Dental Hospital over 3 years by analyzing comprehensive data on chief complaints, treatment methods, and modalities. This study also endeavored to analyze the overall treatment patterns and differences across rare disease categories.

This study explored the dental treatment patterns in pediatric patients with rare diseases who visited Yonsei University Dental Hospital in 3 years. The findings show notable differences in dental care needs and treatment approaches among the rare disease classifications, highlighting the importance of understanding and addressing the specific needs of these patients.

The demographic analysis highlighted a predominance of congenital malformations among the study population, reflecting the higher prevalence of these conditions in pediatric patients. This finding aligns with previous reports that congenital malformations are a major contributor to the overall burden of rare diseases in children[17,27,37]. These patients face numerous dental challenges, including a high prevalence of malocclusion caused by abnormal maxillofacial growth or underdeveloped jaws[8,27]. Furthermore, the incidence of dental developmental anomalies such as congenital tooth agenesis and enamel hypoplasia increased, coupled with an increased occurrence of xerostomia, which further complicates oral health[9,38,39].

The NER group was more likely to present with disabilities (autism, brain lesions, intellectual disabilities, and mental disorders), which is consistent with the complex neurological and cognitive challenges associated with these conditions. This finding indicates that these patients are likely to demonstrate lower cooperation levels during dental procedures, highlighting the need for specialized approaches to effectively manage their dental care[40,41]. Children with intellectual disabilities, executive function disorders, and learning disabilities often struggle to maintain adequate oral hygiene[13,17]. This difficulty, combined with the complexity of their care needs, leads to a heightened susceptibility to dental caries and a higher prevalence of multiple carious lesions[12]. Caregivers also experience significant challenges in managing the oral hygiene of these children, which exacerbates the problem[19,42]. These findings highlight the critical need for integrated care approaches that consider the cognitive and developmental limitations of these patients. Conversely, the END and BLO groups were less likely to have disabilities, indicating that these conditions might not directly impair cognitive and motor functions as severely as NER conditions do.

For the reasons outlined above, patients with rare diseases often require personalized dental care. Oral care provided by dentists includes reviewing the patient’s medical history, conducting an intraoral examination, and offering professional dental treatments such as scaling, plaque control, fluoride application, tongue coating removal, denture care, and managing intraoral wounds and stomatitis[20,21]. In addition to these procedures, an understanding of each rare disease and additional considerations are essential. For example, epilepsy, which represents a large portion of the patient population, requires not only a basic understanding of the classification and clinical presentation of different seizure types but also knowledge of the pharmacotherapy and nonpharmacological treatments (such as vagus nerve stimulation, surgery, and ketogenic diet)[43] that patients may be receiving. In treating epileptic patients, it is essential to carefully manage soft tissue side effects caused by medications and to address potential oral trauma that may occur during seizures. To reduce the likelihood of seizures during treatment, minimizing stress and anxiety during the appointment is crucial, as is providing eye protection to block light that could trigger an epileptic seizure[43,44]. Dentists must always be prepared to handle a seizure should it occur during treatment. In some cases, conscious sedation or general anesthesia may not be contraindicated in patients with epilepsy[45]. As seen in this case, comprehensive insights into each condition and tailored treatment planning are essential in providing dental care for patients with rare diseases.

The NER group was significantly more likely to visit only the pediatric dentistry department, whereas the CON group had a significantly higher frequency of visits to both pediatric dentistry and other departments. This may be attributed to the lower levels of cooperation among patients with NER, making it challenging for them to receive care in multiple departments[46,47]. On the contrary, the CON group often requires additional treatments from other specialties, such as surgery and orthodontics, owing to their structural defects. This highlights the necessity for a multidisciplinary approach in managing the comprehensive dental and medical needs of the CON group[19,48].

The study also demonstrated that the NER and CON groups had significantly different treatment patterns from those with other categories. For instance, intramuscular sedation and outpatient general anesthesia were notably highly used in the CON group, indicating a greater need for intensive sedation and anesthesia management in these patients[3,49-51]. Intramuscular sedation was primarily used to induce a sedated state to reduce patient anxiety or fear during dental treatment[52,53]. It was typically employed in cases where patient cooperation was poor or general anesthesia was not feasible, particularly for short procedures or emergency treatments. The increased use of outpatient general anesthesia can be attributed to the complex dental and medical needs associated with congenital malformations, such as severe seizure disorders, significant behavioral and cognitive impairments leading to poor cooperation, and circulatory abnormalities requiring precise blood pressure management[33,34,37]. Additionally, these patients often face challenges that make routine treatments difficult, necessitating more extensive and invasive procedures[37].

The study findings demonstrated that dental treatment modalities varied significantly among disease categories. For instance, the NER group was less likely to receive preventive or direct restorative treatments such as sealants and composite restoration because of difficulties in patient cooperation and behavioral management. This aligns with the higher prevalence of disabilities in this group, which can pose significant challenges in routine dental care. Additionally, the NER group faces significant challenges with oral hygiene management[13,17] and is prone to dental caries[12]. Therefore, there may be instances where patients are already affected by caries before receiving preventive care[12,13], and high caries prevalence might lead to exclusion from orthodontic treatment indications.

Interestingly, the CON group was more likely to receive extensive dental treatments such as stainless-steel crowns and surgical procedures. This reflects the complex dental needs of these patients, who often present with structural anomalies in the oral and maxillofacial regions, necessitating more durable and invasive treatment options[6,27,37]. Moreover, the frequent use of outpatient general anesthesia in the CON group highlights the need for intensive sedation and anesthesia management, owing to the increased complexity and invasiveness of their required dental procedures.

Although there is a growing demand for orthodontic treatment among patients with rare diseases, applying standard practices remains challenging due to the complexity of their conditions. While the CON group received the most orthodontic treatments, statistical significance was not observed, with specific conditions like atresia of bile ducts and congenital aortic stenosis being more likely to receive fixed orthodontic treatment. In contrast, the NER and CIR groups were significantly less likely to undergo orthodontic treatments, particularly those involving removable appliances. Literature highlights the unique challenges in treating these patients, who exhibit higher rates of dental-skeletal abnormalities, such as dental agenesis, microdontia, maxillary hypoplasia, and oromotor dysfunctions[17,54]. These issues often necessitate longer treatment periods and the use of both fixed and removable appliances, which complicates planning[55]. Additionally, complications like gingivitis, mucosal ulcers, and appliance failure are common and require careful management. High rates of oromotor dysfunctions, such as atypical swallowing and mouth breathing, further complicate treatment, increasing the need for desensitization sessions and more frequent adjustments[55]. To address these challenges, dentists may consider durable appliances, behavioral management techniques, and more frequent follow-ups. Non-invasive interventions like interceptive treatments or clear aligners may also reduce the risks associated with traditional orthodontic appliances.

Although this study provides important insights into the dental care needs of pediatric patients with rare diseases, several limitations should be acknowledged. First, the retrospective design and reliance on EMRs may have introduced biases, particularly in patients with multiple rare diseases, making it challenging to accurately assess the primary factors that influence dental treatment difficulties. Additionally, precise information regarding the specific treatments for each tooth, as well as the number and qualifications of the dentists providing care, was not available. While a total of 14 pediatric dentistry specialists (7 professors and 7 fellows) and 70 general dentists (residents) treated the patients, the exact allocation of dental treatments to these professionals could not be determined. Furthermore, this study lacked a control group of patients without rare diseases, limiting the ability to generalize the findings to the broader pediatric population. The single-institution setting also limits the generalizability of the findings to other settings, and there may be a potential bias related to patient residence, as many patients reside near the institution, potentially affecting the results. This study did not analyze the annual visit frequency or the number of treated teeth per patient, which could provide a more detailed understanding of dental treatment patterns. In future research, we plan to investigate these factors, along with associated treatment costs, to conduct a socioeconomic analysis of dental treatments for patients with rare diseases. Despite these limitations, the study’s strength lies in its substantial data collection from over 700 patients, providing a considerable level of reliability. The single-institution setting also offered the advantage of easy access to and verification of medical records, ensuring accurate and comprehensive data. Additionally, this study is one of the first to focus on dental treatments for pediatric patients with rare diseases in Korea, underscoring its originality and significance.

The study findings offer valuable insights into the dental care needs and challenges faced by this vulnerable population, contributing to the development of more effective and tailored treatment strategies. Future studies, including larger, multicenter studies, are warranted to confirm these findings and explore the effectiveness of different dental treatment strategies for pediatric patients with rare diseases. In addition, tailored dental care protocols that address the specific challenges posed by each rare disease category are needed, with a focus on improving patient cooperation, optimizing anesthesia management, and enhancing the overall quality of life for this patient population.

This study underscores the critical importance of individualized dental care approaches for pediatric patients with rare diseases. The significant variations in treatment needs across rare disease categories highlight the need for tailored dental care protocols and interdisciplinary collaboration. Addressing the unique challenges these patients face can lead to the enhancement of their oral health outcomes and contribute to their overall health and quality of life. Future studies should focus on developing targeted interventions and care models that address the specific challenges associated with managing rare diseases in pediatric dental settings.