Introduction
Generally, rare diseases are defined as conditions with a low prevalence; however, their specific definition varies by country. The World Health Organization defines a disease as rare when it affects less than 5 individuals per 10,000 individuals. In the United States, a rare disease is defined as one that affects fewer than 200,000 individuals. The European Union defines a rare disease as one that affects less than 50 individuals per 100,000 individuals [1]. In Korea, a rare disease is defined as one with either an unknown prevalence due to diagnostic difficulty or one that affects fewer than 20,000 individuals, according to the criteria stipulated by the Ministry of Health and Welfare under the “Rare Disease Control Act” (Article 2). The Korea Disease Control and Prevention Agency (KDCA) officially designates such diseases. The KDCA conducts national statistical programs to monitor the status of patients with rare diseases and publishes the nationally approved annual statistical report on rare diseases, which has been issued annually since December 2020.
Oral and craniofacial issues are common in patients with rare diseases, with approximately 15% exhibiting anomalies such as malocclusion, tooth agenesis, or enamel hypoplasia [2-4]. Poor oral hygiene due to systemic vulnerabilities increases the risk of caries and periodontal disease, affecting both health and quality of life [3,5]. As oral conditions also influence self-esteem and social interaction, early dental visits should be encouraged during childhood [6]. Moreover, children with rare diseases face behavioral and medical challenges that elevate their risk of caries and periodontal disease. Cognitive or neuromuscular impairments and medication side effects—such as xerostomia and gingival overgrowth—limit oral hygiene performance [7]. Irregular home care due to limited cooperation or medical priorities, along with prolonged bottle use, sugary supplements, and long-term drug use, further increase caries risk. These factors should be addressed in individualized oral health planning.
Rare diseases are chronic conditions that require longterm management, with little prospect for complete remission. There is a paucity of affected individuals for whom the burden of treatment is often substantial, socially and economically. While the methods of dental treatment are not inherently different for patients with rare diseases, pediatric patients may experience greater anxiety and fear in the dental setting or may have difficulty cooperating due to their systemic condition, making dental care and oral health management harder [4]. Thus, patient-centered understanding and customized behavior management strategies are required during treatment; ideally, care should be provided in facilities capable of multidisciplinary collaboration, sedation, and general anesthesia.
The recent increase in oral health awareness and dental care for children with rare pathologies in Korea has led to several relevant studies. Yang (2025) analyzed the dental care status and related costs for patients with rare diseases from 2023 to 2025, highlighting the need for a policy foundation [8]. Park (2025) discussed the oral health conditions and treatment strategies for these patients, and Joo et al. (2024) analyzed pediatric patients at Yonsei University Dental Hospital, reporting that treatment approaches varied by disease type [3,4]. These studies emphasize the need for personalized care and strategic approaches based on disease characteristics [3]. However, there is insufficient research analyzing the patterns of dental treatment in pediatric dental departments affiliated with tertiary hospitals that are capable of providing interdisciplinary care for rare diseases. Therefore, this study aims to analyze three years of treatment data from pediatric dental patients with rare diseases who visited the Asan Medical Center (a tertiary care institution) to examine the characteristics of care provided in such a setting and establish reference data capable of contributing to future meta-analyses. In addition, this study was guided by the hypothesis that dental treatment patterns for children with rare diseases may differ across institutions— even within the same disease group—due to differences in hospital infrastructure, provider preferences, and patient population characteristics. By identifying how systemic, clinical, and behavioral variables may influence treatment decisions in a high-capacity tertiary care setting, we aim to provide a broader interpretive framework for understanding inter-institutional variability and future policy planning.
Materials and Methods
This retrospective study was approved by the Institutional Review Board of Asan Medical Center (IRB No. 2025-0218).
1. Study subjects
The participants of this study were patients who visited the Asan Medical Center’s Department of Pediatric Dentistry between January 1, 2022, and December 31, 2024. Patients were retrospectively selected if they had been diagnosed with at least one of the 1,314 rare diseases officially recognized by the KDCA. In total, 922 patients were ultimately included in the study. Data were collected through electronic medical record analyses performed using the electronic medical record system at Asan BiomedicaL research Environment (ABLE), which included outpatient, inpatient, and emergency visit records. For patients diagnosed with multiple rare diseases, only the primary diagnosis that necessitated hospital-based care was used for classification [9].
2. Diagnosis and classification
This study used diagnostic codes from the Korean Standard Classification of Diseases (KCD) to identify rare diseases. The KCD system categorizes diseases based on similarities in etiology and is widely used in medical records, mortality statistics, and disease incidence data. The 8th edition of the KCD, in effect since January 1, 2016, is adapted from the World Health Organization’s International Classification of Diseases, 10th Revision (ICD-10), to align with the Korean healthcare system [9]. Diseases were grouped according to the initial letters of the KCD codes, which correspond to major diagnostic categories.
The following six groups were classified according to the KCD codes:
● The CON group (Q00 - Q99): Congenital malformations, deformations, and chromosomal abnormalities
▪ Q00 - Q07 Congenital malformations of the nervous system
▪ Q10 - Q18 Congenital malformations of eye, ear, face, and neck
▪ Q20 - Q28 Congenital malformations of the circulatory system
▪ Q30 - Q34 Congenital malformations of the respiratory system
▪ Q35 - Q37 Cleft lip and cleft palate
▪ Q38 - Q45 Other congenital malformations of the digestive system
▪ Q50 - Q56 Congenital malformations of genital organs
▪ Q60 - Q64 Congenital malformations of the urinary system
▪ Q65 - Q79 Congenital malformations and deformations of the musculoskeletal system
▪ Q80 - Q89 Other congenital malformations
▪ Q90 - Q99 Chromosomal abnormalities, not elsewhere classified
● The NER group (G00 - G99): Diseases of the nervous system
▪ G00 - G09 Inflammatory diseases of the central nervous system
▪ G10 - G14 Systemic atrophies primarily affecting the central nervous system
▪ G20 - G26 Extrapyramidal and movement disorders
▪ G30 - G32 Other degenerative diseases of the nervous system
▪ G35 - G37 Demyelinating diseases of the central nervous system
▪ G40 - G47 Episodic and paroxysmal disorders
▪ G50 - G59 Nerve, nerve root, and plexus disorders
▪ G60 - G64 Polyneuropathies and other disorders of the peripheral nervous system
▪ G70 - G73 Diseases of myoneural junction and muscle
▪ G80 - G83 Cerebral palsy and other paralytic syndromes
▪ G90 - G99 Other disorders of the nervous system
● The BLO group (D50 - D89): Diseases of the blood and blood-forming organs, including certain immune disorders
▪ D50 - D53 Nutritional anemias
▪ D55 - D59 Haemolytic anemias
▪ D60 - D64 Aplastic and other anemias
▪ D65 - D69 Coagulation defects, purpura, and other hemor-rhagic conditions
▪ D70 - D77 Other diseases of blood and blood-forming organs
▪ D80 - D89 Certain disorders involving the immune mechanism
● The CIR group (I00 - I99): Diseases of the circulatory system
▪ I00 - I02 Acute rheumatic fever
▪ I05 - I09 Chronic rheumatic heart diseases
▪ I10 - I15 Hypertensive diseases
▪ I20 - I25 Ischemic heart diseases
▪ I26 - I28 Pulmonary heart disease and diseases of pulmonary circulation
▪ I30 - I52 Other forms of heart disease
▪ I60 - I69 Cerebrovascular diseases
▪ I70 - I79 Diseases of arteries, arterioles, and capillaries
▪ I80 - I89 Diseases of veins, lymphatic vessels, and lymph nodes, not elsewhere classified
▪ I95 - I99 Other and unspecified disorders of the circulatory system
● The END group (E00 - E90): Endocrine, nutritional, and metabolic diseases
▪ E00 - E07 Disorders of thyroid gland
▪ E10 - E14 Diabetes mellitus
▪ E15 - E16 Other disorders of glucose regulation and pancreatic internal secretion
▪ E20 - E35 Disorders of other endocrine glands
▪ E40 - E46 Malnutrition
▪ E50 - E64 Other nutritional deficiencies
▪ E65 - E68 Obesity and other hyper alimentation
▪ E70 - E90 Metabolic disorders
● The Etc. group: Miscellaneous diseases that did not fall into the above groups but were observed in pediatric dental visits, including categories A, C, E, F, H, J, K, and M [9].
3. Variables
Patient demographic and dental treatment data were collected from the ABLE system. The selection of variables was based on the study design proposed by Yoo, which was referenced to enhance the potential utility of this study as reference data for future meta-analyses [1]. The data collected included the patient’s sex, age at the first pediatric dental visit (in months), date of visit, chief complaint, treatment content, and treatment method. The chief complaint refers to the primary reason a patient or guardian sought care or treatment. In this study, chief complaints were classified into the following categories: examination, dental caries, dental trauma, orthodontic treatment, congenitally missing teeth, supernumerary teeth, soft tissue disease, ectopic eruption, cyst, temporomandibular disorders, developmental anomalies, and wisdom teeth [10].
In this study, treatment methods were categorized as follows: non-sedation dental treatment, inhalation sedation using nitrous oxide, sedation treatment using chloral hydrate or midazolam, general anesthesia during hospitalization due to underlying medical conditions, and outpatient general anesthesia.
The treatment content was categorized into five groups: examination and prophylactic treatment, restorative treatment, pulp treatment, surgical treatment, and orthodontic treatment. Subcategories under examination and prophylactic treatment included examination only, primary tooth extraction, topical fluoride application, scaling, and sealant. Restorative treatment included composite resin, glass ionomer, stainless steel crown, and zirconia crown. The number of treated teeth was also recorded. Pulp treatment included pulpotomy and pulpectomy for primary teeth, as well as pulp treatment for permanent teeth, with the number of treated teeth noted.
Surgical treatment was classified as resin wire splint and suture for trauma, permanent tooth extraction, supernumerary tooth extraction, and frenectomy. Orthodontic treatment was subdivided into space maintainers (e.g., band and loop, lingual arch), use of removable appliances, and use of fixed appliances.
4. Statistical analysis
All statistical analyses were performed using the IBM SPSS Statistics version 29.0 (SPSS Inc., Chicago, IL, USA). Continuous data are presented as mean values with their corresponding standard deviation or median values with their corresponding interquartile ranges. Categorical variables are presented as frequencies and percentages. For demographic analyses, Levene’s test was first conducted to assess the homogeneity of variance in the age at the first visit (in months). Subsequently, group-wise comparisons were performed using regression-based analyses with dummy-coded disease groups. For categorical variables such as sex, visits to other dental specialties, treatment methods, and treatment contents, chisquare tests were used. In cases where the expected cell count was less than 5, Fisher’s exact test was employed.
To evaluate the associations between the rare disease groups and treatment methods or contents, multivariable binary logistic regression analysis was conducted. The measure of association employed in this study was the odds ratio with its 95% confidence interval. p < 0.05 was considered statistically significant.
To address potential confounding factors, a multivariate logistic regression analysis was conducted with intramuscular sedation as the dependent variable. Independent variables included gender, age at first dental visit, and diagnostic group. The congenital disease group (CON) was used as the reference category. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each variable. Model fit was assessed using the Hosmer-Lemeshow goodness-of-fit test.
Results
1. Demographic characteristics
A total of 922 patients (492 males and 430 females) were included in the study. There was no statistically significant difference in sex distribution across the groups, except in the CIR group, where the number of female patients was significantly higher than that of male patients.
The mean age (in months) at the first visit to the pediatric dental department was 62.33 ± 51.29 months, and a statistically significant difference in age was observed among the groups. Regarding visits to other dental specialties in addition to pediatric dentistry, 5.10% of patients also visited departments such as oral surgery, conservative dentistry, or orthodontics, whereas 94.90% received care solely in the pediatric dental department. Only in the CIR group was there a statistically significant association with visits to other dental specialties. No such association was found in the remaining groups (Table 1). The age at the first dental visit differed among disease groups. The CON group showed the earliest median age (40.5 months), while the Etc. group had the most delayed visits (78.0 months). Interquartile ranges and full age ranges also varied substantially by group (Table 1).
Among the 922 patients analyzed, a total of 87 had a formally registered disability. The CON group accounted for the majority (n = 58), followed by the NER (n = 12), CIR (n = 6), Etc. (n = 5), BLO (n = 3), and END (n = 3) groups (Table 1). Given that disability status was not a primary outcome of this study and the group distribution was highly imbalanced, results were summarized descriptively (Table 1).
2. Classification and distribution of rare diseases
Patients who visited the pediatric dental department of Asan Medical Center between January 1, 2022, and December 31, 2024, were categorized into six rare disease groups. The largest proportion belonged to the CON group (69.63%), followed by the NER (11.17%), BLO (8.03%), Etc. (4.66%), CIR (4.45%), and END (4.23%) groups (Fig. 1).
3. Chief complaints and dental treatment methods by disease classification
The most common chief complaint among patients was dental examination (53.48%), followed by dental caries (21.22%) and orthodontic treatment (8.46%) (Fig. 2). Multiple chief complaints for a single patient were counted individually. The chief complaints did not differ significantly among the groups; however, in the NER group, the proportion of orthodontic treatment as the chief complaint was only 2.80%, placing it fifth in terms of frequency, in contrast to other groups where it ranked third (6.78% ‒ 11.82%). In the CON group, bruxism was reported as a chief complaint more frequently than in other groups, ranking fourth. The proportion of participants with dental trauma as the chief complaint was higher in the NER (9.09%) and Etc. (9.26%) groups than in the other groups (Fig. 3).
A statistically significant difference was observed in the rate of non-sedation dental treatment, with 80.77% of patients in the CIR group receiving treatment without sedation (p= 0.013). No cases of sedation using chloral hydrate or midazolam were recorded in the CIR group, whereas the BLO group showed a borderline significant result with a 1.96% usage rate (p= 0.073). Inpatient general anesthesia was most frequently performed in the NER group (18.42%), and its rate differed significantly among the groups (p= 0.033, Fig. 4).
When comparing the dental treatment patterns among the groups, the END group had significantly higher rates of scaling (p < 0.0001) and permanent tooth extraction (p= 0.013). The NER group showed a significantly lower probability of receiving stainless steel crown treatment (p= 0.04) and orthodontic treatment with fixed appliances (p= 0.05) compared to the other groups. In the CIR group, the probability of receiving topical fluoride application as a preventive measure was significantly higher than in the other groups (p= 0.042). In contrast, the CON group had a significantly lower likelihood of undergoing scaling (p= 0.001) and permanent tooth extraction (p= 0.04) compared to the other groups (Table 2).
4. Multivariable logistic regression analysis by rare disease classification
Logistic regression analysis revealed significant associations between the rare disease group classification and several variables, including age (in months) at the first pediatric dental visit, visits to other dental specialties, and the sedation method employed (Table 3).
No statistically significant sex differences were observed across the groups (p < 0.05); however, in the CIR group, there was a trend toward a higher proportion of female patients compared to male ones, although the difference did not reach statistical significance (OR = 1.83, p= 0.073). Age at the first visit to the pediatric dental department was significantly associated with classification into the BLO, END, and CON groups. In the BLO (OR = 1.01, p= 0.001) and END (OR = 1.01, p= 0.001) groups, age was positively correlated with group classification. In contrast, in the CON group, the likelihood of classification decreased with increasing age at the first visit (OR = 0.99, p < 0.001). These findings suggest that age may reflect disease-specific characteristics, the timing of symptom onset, or the severity of systemic conditions across the rare disease groups.
Patients who received care from other dental specialties in addition to pediatric dentistry were significantly more likely to belong to the Etc. group (OR = 3.650, p= 0.007), indicating a greater need for multidisciplinary care in this group. Additionally, patients who received dental treatment in a non-sedation setting were significantly more likely to belong to the CIR group (OR = 3.550, p= 0.013). Sedation using nitrous oxide (N2O) and outpatient general anesthesia did not show statistically significant associations with any group. Although midazolam-based sedation was not significantly associated with group classification, there was a trend toward lower usage in the BLO group (OR = 0.13, p= 0.073). In contrast, inpatient general anesthesia was significantly associated with the NER group (OR = 4.160, p= 0.033), indicating a higher level of medical complexity or procedural difficulty in this group.
Among the specific dental treatment variables, sealant treatment was more likely to be administered in the BLO group (OR = 2.510, p= 0.050). No significant group differences were found for composite resin treatment. Stainless steel crowns were significantly more frequent in the BLO group (OR = 2.810, p= 0.043) and significantly less frequent in the NER group (OR = 0.180, p= 0.024). There were no significant differences in pulp treatment, surgical treatment, or use of fixed or removable orthodontic appliances.
5. Frequency of dental treatment by group
When comparing the number of treated teeth for restorative and pulp therapies, the CIR group had the lowest average number of composite resin restorations per patient (0.78 teeth), and the END group had the highest (1.18 teeth). The percentage of patients who received five or more composite resin restorations was lowest in the CIR group (2.44%), followed by BLO (4.05%), Etc. (4.54%), CON (4.98%), END (7.69%), and NER (7.77%). For glass ionomer restorations, the CON group had the lowest average number of treated teeth per patient (0.07 teeth), and the CIR group had the highest (0.22 teeth). For stainless steel crowns, the END group had the lowest average number of treated teeth per patient (0.13 teeth), whereas the CIR group had the highest (0.83 teeth). The percentage of patients who received five or more stainless steel crowns was 0.97% in the NER group, 2.44% in the CIR group, and 4.21% in the CON group.
For pulp treatment, the average number of treated teeth per patient was lowest in the END group (0.03 teeth) and highest in the CIR group (0.37 teeth). The proportion of patients who received at least five pulp treatments was 0.97% in the NER group, 2.44% in the CIR group, and 0.78% in the CON group (Table 4).
6. Multivariate logistic regression analysis
A multivariate logistic regression analysis was conducted to examine differences in the use of intramuscular sedation across diagnostic groups, with gender and age at first dental visit included as covariates (Table 5).
Patients in the CIR group showed significantly lower odds of receiving intramuscular sedation compared to the CON group (OR = 0.157, 95% CI = 0.025 ‒ 0.985, p= 0.048), and a similar trend was observed in the NER group (OR = 0.160, 95% CI = 0.000 ‒ 1.620, p= 0.017).
No statistically significant differences were found in the BLO, END, or ETC groups.
Additionally, increased age at first visit was associated with a reduced likelihood of sedation (OR = 0.991, p= 0.031).
Discussion
This study analyzed the patterns of dental treatment among 922 pediatric patients with rare diseases who visited Asan Medical Center (AMC)’s Department of Pediatric Dentistry over a three-year period from January 1, 2022, to December 31, 2024. Significant differences were observed in age and distribution of the initial dental visit, use of sedation or general anesthesia, and types of treatment according to the classification of rare diseases.
Given the broad diagnostic categories used in this study, clinical characteristics within each rare disease group may explain the observed variations in dental treatment. Below, we describe relevant systemic and behavioral features associated with each group that likely influenced sedation needs, preventive care, and treatment planning. The five major groups—BLO, CIR, END, NER, and CON—were classified based on their high frequency among pediatric patients with rare diseases who visited our department during the study period. These groups were selected not only for their prevalence but also for the presence of shared systemic and oral characteristics, which allowed for consistent intra-group comparisons. Disease categories with low patient counts or heterogeneous oral manifestations were grouped under “Etc.” to ensure analytical clarity and statistical validity.
The CON group includes patients with craniofacial anomalies such as Crouzon syndrome, osteogenesis imperfecta, and Ehlers-Danlos syndrome, often presenting with enamel hypoplasia and skeletal disproportions [11-13]. These conditions are associated with struc-tural fragility of bone and soft tissue, increasing risks such as hemorrhage or trauma during dental care. As a result, long-term monitoring and orthodontic or dentofacial orthopedic treatment are frequently required [14].
The NER group includes patients with central and peripheral nervous system disorders, such as Lennox- Gastaut syndrome and West syndrome. These patients frequently exhibit cognitive impairment, behavioral difficulties, and seizures, which limit cooperation and complicate dental management [15]. As a result, sedation or general anesthesia is often required to ensure safe and effective care [16].
The BLO group includes patients with hematologic and immune disorders, such as DiGeorge syndrome and hemophilia. Due to frequent bleeding tendencies and increased risk for infective endocarditis, thorough coagulation assessment and preventive strategies are essential [17]. Treatment planning often requires infection control measures, including platelet transfusions or antibiotic prophylaxis [18].
The CIR group includes patients with cardiovascular disorders, such as Moyamoya disease and a history of infective endocarditis. Dental treatment requires careful attention to hemodynamic stability, sedation decisions, and the use of antibiotic prophylaxis [19].
The END group includes endocrine and metabolic disorders, such as Addison’s disease, hypophosphatasia, and glycogen storage disease. These patients are susceptible to metabolic imbalance, abnormal bone development, and infection risk due to neutropenia. Dental care requires prior medical evaluation and planning to prevent complications such as bleeding or premature tooth loss [20,21].
The Etc. group consists of patients with heterogeneous diseases categorized under codes A, C, E, F, H, J, K, and M. Due to wide pathophysiological variability, treatment requires flexible, patient-centered strategies rather than standardized protocols.
The mean age at the first visit was 62.33 ± 51.29 months, and it differed significantly among the BLO, END, and CIR groups. This suggests that the timing of dental visits varies depending on the onset of disease symptoms or diagnosis in each group. Notably, all groups except the CON group showed a trend of delayed first visits to the pediatric dental clinic. To further characterize the variation in the timing of the first dental visit, descriptive statistics of age at first presentation were analyzed by rare disease group (Table 1). The CON group exhibited the earliest dental visits, with a median age of 40.5 months. This may reflect earlier diagnosis and more frequent referral to dental care in patients with congenital malformations. The NER group showed a median age of 56.5 months, possibly related to early recognition of behavioral or developmental challenges. The BLO and CIR groups presented at median ages of 63.0 and 78.0 months, respectively. These findings highlight that the timing of first dental visits is influenced not only by disease severity and onset, but also by care coordination and diagnostic timing across different rare disease types [22]. The timing and reason for the first dental visit in pediatric patients are influenced by various factors, including social welfare systems, family socioeconomic status, and educational level [23]. The International Association of Pediatric Dentistry recommends initiating dental visits before the age of 12 months to facilitate early prevention and diagnosis [24]. Although the CON group showed the lowest mean age at the first visit among all groups (53.83 months), this still indicates that dental visits are largely driven by reactive care in response to problems rather than proactive, preventive management. Furthermore, the overall mean age of 62.33 months in this study is significantly later than the recommended age of 12 months, and also exceeds the average first visit age of 4.24 years reported in healthy children from a previous study [25]. This suggests that children with rare diseases tend to initiate dental care later than both clinical guidelines and the general pediatric population without rare diseases.
In this study, the largest proportion of patients belonged to the CON group, comprising 69.63% of the total sample (642 out of 922 patients), followed by the NER, BLO, Etc., CIR, and END groups in descending order. This distribution reflects the clinical reality that congenital anomalies and genetic disorders are among the most common conditions in pediatric patients with rare diseases and are frequently encountered in dental practice [22].
Among children with rare diseases who visited the AMC during the three-year study period, the most frequently reported chief complaints were dental examination (53.48%), dental caries (21.22%), and orthodontic treatment (8.46%). Although the distribution of complaints did not differ significantly across groups, certain trends were observed. In the NER group, orthodontic-related complaints accounted for only 2.80%, ranking fifth among all complaints. This may be due to the nature of neurodevelopmental disorders, such as West syndrome and Lennox-Gastaut syndrome, where malocclusions like a high-arched palate are common, but cognitive impairment and learning disabilities limit patient cooperation, thereby reducing the feasibility and demand for orthodontic care [16,26]. Additionally, dental trauma was more frequently reported as a chief complaint in the NER group than in other groups. This is likely due to increased vulnerability to external injury associated with neurological conditions, such as brain damage, frequent seizures, and gait disturbances [26].
In this study, the highest proportion of patients who received dental treatment without sedation (nonsedation) was observed in the CIR group, at 80.77% (Fig. 4). Our logistic regression analysis also revealed a significantly increased likelihood of receiving treatment without sedation in the CIR group (OR = 3.550, p= 0.013). This suggests that patients with circulatory system disorders, in the absence of other genetic or systemic comorbidities, are more likely to demonstrate sufficient cooperation to receive dental care in an outpatient setting. However, it is important to note that excessive stress, crying, or hyperventilation can lead to cerebrovascular constriction and ischemia, potentially resulting in neurological complications. Therefore, even in cooperative patients, minimizing pain and anxiety during treatment is critical. In cases where fear or anxiety is excessive, general anesthesia may be required; in such instances, careful monitoring is necessary to prevent complications such as hypotension, hypocapnia, or hypercapnia [16].
Despite the known behavioral challenges in syndromic cases, a notable proportion of patients in this study were treated without sedation (Fig. 4). Several clinical factors may account for this outcome. General anesthesia, while often considered for extensive dental caries, may not be justified for every newly developing lesion, particularly given the medical risks and logistical burdens associated with repeated exposure. In such instances, dentists may prioritize non-invasive preventive strategies such as fluoride varnish or silver diamine fluoride. Moreover, in many syndromic and neurodevelopmental conditions, pharmacologic sedation—especially N2O—is often ineffective in alleviating dental fear or enhancing cooperation. For example, patients with Lennox-Gastaut syndrome, West’s syndrome, or Prader-Willi syndrome frequently exhibited poor responsiveness to minimal sedation due to cognitive and neurologic impairments, thereby necessitating the use of physical restraint or individualized behavioral approaches [27]. In case of cardiovascular anomalies such as Tetralogy of Fallot or single ventricle, pharmacologic sedation was often deliberately avoided due to concerns about hemodynamic instability [28]. Furthermore, early diagnosis and continuous follow-up in conditions like Beckwith-Wiedemann syndrome and Noonan syndrome allowed dental care to begin at less complex stages, enabling preventive treatments without sedation. These trends are also consistent with our institution’s conservative approach to sedation, in which pharmacologic methods are reserved for cases where behavioral management is clearly insufficient and medical risks are thoroughly evaluated.
The rate of administration of general anesthesia during inpatient hospitalization was significantly higher in the NER group (18.42%). Logistic regression analysis confirmed a statistically significant association (OR = 4.160, p= 0.033, Table 3). This reflects the common need for general anesthesia in patients with neurological disorders, who have difficulty cooperating or are unable to tolerate dental procedures under minimal sedation, necessitating the use of general anesthesia. In addition, inpatient care may be required to observe and manage neurological symptoms such as seizures during treatment.
Distinct patterns were also observed in specific types of dental treatment by group. The NER group showed significantly higher rates of composite resin and stainless steel crown restorations, with the highest proportion of patients receiving five or more composite resin restorations. As previously discussed, this may be attributed to the challenges faced by these patients in maintaining adequate oral hygiene due to cognitive impairment, communication difficulties, and fine motor limitations, as well as the xerostomia and gingival overgrowth associated with antiepileptic medications— factors that contribute to a higher incidence of dental caries and, consequently, a greater need for restorative treatment [16,29,30]. This finding contrasts with previous studies reporting lower rates of restorative treatment in patients with neurological disorders, suggesting the need for further research that considers inter-institutional differences [3].
Logistic regression analysis revealed that patients in the BLO group had a significantly higher likelihood of receiving sealant applications compared to the other groups (OR = 2.510, p= 0.050). This can be interpreted as the result of relatively good patient cooperation in this group, as sealant treatment requires a dry field, minimal movement, and the ability to remain still for several minutes. Unlike restorative or surgical procedures that can be performed under sedation or general anesthesia, sealants are typically applied during routine outpatient visits, making patient cooperation a critical factor in their treatment. Moreover, this trend may also be influenced by the underlying systemic conditions in the BLO group, such as bleeding tendencies and immunocompromised states, which increase the risk of complications during invasive procedures. As a result, clinicians may prioritize preventive strategies to minimize procedural risks and to support oral health maintenance in medically vulnerable patients [31].
In contrast, the rate of orthodontic treatment using fixed appliances was significantly lower in the NER group than in the other groups. This aligns with the earlier observation that orthodontic-related complaints were less common in the NER group (2.80%).
In this study, the CIR group showed the highest rate of pulp treatment, suggesting that dental caries in these patients were often not managed at an early stage. This pattern could be associated with a healthcare environment in which clinical attention is predominantly focused on systemic disease management or with caregivers’ tendency to consider dental care less important. For this population, a strong preventionfocused approach must be emphasized, and systematic support for early intervention and continuous follow-up for caries monitoring is essential. The background factors contributing to inadequate caries control are likely multifactorial, including the prioritization of systemic treatment based on medical history, financial burden, and insufficient awareness regarding oral health. These considerations should be integrated into future oral health promotion strategies for children with rare pathologies.
There was a statistically significant difference in the rate of scaling between the END and CON groups, with the END group showing a significantly higher rate (p= 0.000) and the CON group a significantly lower rate (p= 0.001). The higher rate in the END group may be attributed to systemic factors such as immunosuppression, xerostomia, and periodontal abnormalities, as well as an oral environment worsened by corticosteroid use [21,32]. In contrast, the lower rate in the CON group is unlikely to reflect better periodontal health, but rather anatomical, physiological, and behavioral limitations. For example, congenital heart diseases common in Noonan syndrome may increase the risk of infective endocarditis during scaling, and cognitive or behavioral difficulties in Prader-Willi syndrome may hinder the provision of preventive care [33].
The rate of permanent tooth extraction was significantly higher in the END group than in the CON group (p= 0.013), primarily due to tooth mobility caused by trauma or severe caries. For example, in Lesch-Nyhan syndrome, self-injurious behavior can lead to repeated oral trauma, resulting in the need for anterior tooth extraction [34]. In contrast, the CON group showed a significantly lower extraction rate (p= 0.04), with most extractions performed for orthodontic purposes. This may reflect better cooperation during orthodontic treatment and earlier identification of treatment needs. Many patients in this group present with congenital craniofacial anomalies, leading to earlier initiation of dental monitoring, and early intervention is more feasible in tertiary hospitals where dentofacial orthopedic care is integrated. At AMC, a substantial portion of patients in the CON group were diagnosed with Noonan syndrome, CHARGE syndrome, or Down syndrome. Despite varying degrees of intellectual disability, many of these patients were able to successfully undergo orthodontic treatment involving extractions, particularly with active support from caregivers [35-37].
While these cases illustrate the potential for early intervention under supportive conditions, the overall oral health status of children with rare diseases remains underexamined and requires broader assessment. In order to more clearly interpret the oral health status of pediatric patients with rare diseases, we conducted a retrospective investigation of the dmft/DMFT indices in patients whose chart records were available. Although radiographic data could not be accessed due to institutional review board restrictions, partial assessment of dental caries was possible based on the available dental chart entries. The average dmft/DMFT index was 5.94, which is substantially higher than the national average of 1.91 reported for 12-year-old children in the 2018 National Oral Health Survey [38]. A recent study using data from the Korea National Health and Nutrition Examination Survey (KNHANES) also reported a significant decline in caries prevalence among children and adolescents aged 10 to 18 years, from 72.1% in 2007 to 55.9% in 2019 [39]. In contrast, the high level of caries observed in children with rare diseases in our study indicates a persistent burden. These findings suggest that such children may experience systemic barriers limiting access to dental treatment and preventive care. Accordingly, more proactive caries prevention strategies, regular oral health checkups, and financial support for dental treatment are needed to address these unmet needs.
This study aligned its analytical framework and disease classification method with those of previous studies, enabling future comparisons and integrated analyses of treatment trends among children with rare conditions domestically and internationally. By employing a consistent set of variables and classification criteria, this study enhances its potential utility as a reference dataset for multicenter studies and future meta-analyses. Such methodological consistency is expected to contribute to the development of more objective and generalizable evidence for dental care in children with rare diseases, extending beyond the findings of a single-institution study.
The findings of this study suggest that not only do the characteristics of patients vary depending on the classification of rare diseases, but also that patient composition and treatment patterns are influenced by the institutional capacity of the medical facility. As of 2024, AMC is the largest tertiary care hospital in Korea, with an average of 11,402 outpatient visits per day and a total of 2,432 beds [40]. In contrast, a previous study analyzing the dental treatment patterns of pediatric patients with rare diseases was conducted at a hospital with an average of 6,850 outpatient visits per day and 2,437 beds [41]. Given that the number of patients with rare diseases may correlate with the overall outpatient volume of a hospital, such institutional capacity indicators could serve as reference criteria when formulating administrative and financial support policies for pediatric dental care in this population.
Building upon these observations, we revisit the hypothesis proposed in the Introduction—that dental treatment patterns for pediatric patients with rare diseases may differ across institutions, even within the same disease group, due to differences in hospital structure, provider preferences, and patient population characteristics. Although this study was limited to a single tertiary institution and did not allow for interinstitutional comparison, several observations suggest that treatment decisions may indeed be influenced by non-disease-related factors. For instance, the notably high rate of non-sedation treatments in the CIR group may reflect clinician judgment to avoid sedation in medically vulnerable patients, rather than better cooperation alone. Similarly, differences in restorative material selection across disease groups may not be solely attributable to caries severity but may also reflect factors such as patient compliance, available appointment time, and operator preferences.
These findings lend partial support to the proposed hypothesis. However, conclusive validation would require multi-center studies or mixed-methods research that incorporates institutional, behavioral, and providerlevel data. Future research should investigate how differences in sedation thresholds, access to general anesthesia, and staffing systems affect clinical decisionmaking across hospitals. Identifying and addressing these structural factors could help reduce variability in treatment approaches and support the development of national-level guidelines for rare disease dental care.
Based on the challenges identified in this study— including delays in first dental visits and inconsistencies in treatment accessibility—we propose several practical strategies to support early dental care for children with rare diseases. At the institutional level, tertiary hospitals could implement an internal registry system for rare disease patients to track oral health needs and guide followup. Additionally, educational brochures that emphasize the appropriate timing and importance of the first dental visit can be distributed to relevant departments—such as pediatrics, genetics, and neonatology—to encourage timely referrals to pediatric dental care. Finally, efforts should be made to proactively integrate existing national oral health screening programs into the care of rare disease patients by establishing verification and referral processes at the point of contact in hospitals. These approaches may enhance coordination, promote early detection, and reduce disparities in dental service delivery for this vulnerable group.
To reduce the number of cases in which dental caries progress without timely and appropriate intervention, efforts should not be limited to individual-level preventive education. Rather, national-level support is required to ensure that patients with systemic diseases or disabilities can maintain adequate oral health. In particular, for patients who require repeated dental visits or professional preventive care, it is essential to alleviate financial burdens through reinforced healthcare coverage and to expand oral health-based care coordination services. These measures are critical to overcoming the structural barriers that deprioritize dental treatment and ensuring oral health equity for children who are inherently more susceptible to caries due to their medical conditions.
At our institution, a structured recall system is implemented for all pediatric patients with rare diseases. Follow-up appointments are routinely scheduled at intervals of 3 to 6 months depending on clinical needs, and more frequently for patients undergoing active treatment such as orthodontic care. Compliance is monitored through the hospital’s electronic medical record system. This recall protocol ensures continuity of care and supports early detection and timely management of dental issues, even in medically complex cases, regardless of disease classification.
One important component of national support is the reduction of financial barriers to dental care. In this context, several countries have implemented programs to ease the dental treatment burden for children with rare diseases. In the United States, the Delta Dental Foundation supported access to dental care with a $30,000 grant for children with Cornelia de Lange syndrome [42]. The EveryLife Foundation for Rare Diseases also connects patients and caregivers to a range of financial assistance programs, including NeedyMeds, which offers information on low-cost dental clinics, and Chive Charities, which supports uncovered treatment expenses [43]. In Canada, the Canadian Dental Care Plan (CDCP) provides income-based government subsidies for essential dental services, such as examinations, restorations, extractions, and endodontic treatments [44]. Although rare diseases are not explicitly listed among the eligibility criteria, children who meet income or disability-related requirements— including some with rare conditions—may qualify for support under this plan. These international examples underscore the urgent need for similar policy and financial strategies in Korea to ensure oral health equity for children with rare diseases.
In addition to international examples, Korea has also implemented policies aimed at reducing the financial burden of dental care for children with rare diseases—for instance, providing insurance coverage for orthodontic and dentofacial orthopedic treatment in patients with congenital craniofacial anomalies [45]. Among the 922 pediatric patients with rare diseases included in this study, 122 (13.2%) were identified as having diagnoses that qualify for such insurance coverage. The majority of these patients (n = 107) belonged to the CON group, while the remaining were distributed across the NER (n = 6), END (n = 3), BLO (n = 2), CIR (n = 2), and Etc. (n = 2) groups. However, only 14 of these 122 patients had received an orthodontic diagnosis or were undergoing orthodontic or orthopedic treatment, 12 of whom were in the CON group, and one each in the END and NER groups. The presence of a national insurance policy may have contributed, at least in part, to the higher orthodontic treatment rate observed in the CON group, and this relationship is modestly reflected in the treatment distribution presented in Table 2. Nevertheless, these findings suggest that, despite the existence of institutional support for orthodontic and orthopedic care, the actual uptake of treatment remains low due to factors such as limited patient cooperation, prioritization of systemic disease management, and delays in referral. To close this gap and ensure that children with complex medical conditions have meaningful access to dental care, stronger coordination between healthcare policy and clinical practice is warranted.
AMC’s Department of Pediatric Dentistry operates an integrated care system involving specialists in medical genetics, pediatric neurology, pediatric cardiology, and other relevant fields. This structure enables early multidisciplinary planning that includes antibiotic prophylaxis assessment, systemic evaluation, and anesthesia risk assessment. In practice, patients often undergo collaborative review with departments such as pediatric neurology, cardiology, or hemato-oncology. For patients requiring sedation or general anesthesia, drug interactions with existing medications are reviewed, and anesthetic risk is assessed in collaboration with anesthesiologists and medical teams. This well-established system supports safe, individualized dental care and helps explain the predominance of patients in the CON group (69.63%) observed in this study. Compared to university-based settings, tertiary hospitals offer distinctive advantages in managing medically complex patients, including the ability to perform high-risk procedures promptly and to coordinate care across specialists. In summary, the structural features of pediatric dental care within a tertiary hospital setting significantly influence the composition of the patient population and treatment patterns, possibly serving as a valuable reference in the design of effective care systems for managing oral health in children with rare diseases.
We identified 87 patients with formally registered neurodevelopmental disabilities, including intellectual disability, autism spectrum disorder, and cerebral palsy. These patients were distributed across all rare disease groups, as summarized in Table 1. However, because disability registration is not required for dental care at our institution, the actual prevalence is likely underreported. The limited and uneven data prevented meaningful statistical analysis. Nonetheless, this preliminary overview provides valuable clinical context for understanding behavioral cooperation and sedation planning. Future studies should incorporate standardized behavioral assessments or structured documentation of disability status to better inform individualized dental care for patients with rare diseases.
Nevertheless, this study has several limitations that are worth mentioning. First, as a single-center retrospective study, its findings may not be generalizable to the overall population of pediatric patients with rare diseases. Therefore, additional multicenter studies conducted using data from various institutions or regional networks are needed. Second, the disease classification employed in this study was based on representative diagnostic codes for each group, which limited the ability to reflect detailed clinical characteristics such as disease subtype, severity, treatment course, and comorbidities. Given the diversity of rare diseases, such factors may significantly influence dental care approaches and levels of complexity; hence, more precise classification and analysis will be necessary. To partially address this limitation, we reviewed and categorized the specific diagnoses within each major disease group and presented them in a detailed description of the subgroups to enhance transparency and clinical context. However, due to the small number of cases for many individual diagnoses, further statistical stratification by disease subtype or severity was not feasible, as it would have resulted in insufficient statistical power and unreliable inferences. Future studies with larger and more diverse samples are warranted to explore stratified analyses based on specific syndromes or functional impairments. Such efforts may lead to a more individualized understanding of dental needs and contribute to the development of evidencebased clinical guidelines for pediatric patients with rare diseases. Third, the study period was limited to three years, which may not be sufficient to evaluate long-term treatment outcomes or changes over time. Fourth, while this study focused on the frequency and type of dental treatments provided, it did not assess qualitative factors such as patient or caregiver satisfaction, quality of life, or perceptions and accessibility of dental care. Future research should incorporate these qualitative indicators to better reflect patients’ true needs and experiences.
Conclusion
This study identified significant differences in dental visit timing, sedation use, and treatment types among pediatric patients with rare diseases, varying by disease group. Our findings, when compared to those of previous studies, suggest that institutional capacity and patient composition may influence treatment decisions. These results highlight the need for disease-specific preventive care, early intervention, and better integration between clinical care systems and public health policy. Multicenter studies are needed to establish standardized guidelines and promote equitable access to dental care in this vulnerable population.
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