Early childhood caries (ECC) is recognized as a significant and prevalent oral health issue among young children, aged under six years (1). The estimated prevalence of ECC was 49% globally and 72% in the Middle East (2). If left untreated, dental caries can have adverse effects on a child's development. It may cause oral health–related quality of life (OHRQoL) issues, such as dental pain, difficulty chewing, poor appetite, weight loss, sleep disturbances, and low academic performance (3–7).

Several indices are used to describe the dental caries status at the national and community level. In oral epidemiological studies, dental caries is commonly evaluated by the DMFT and ICDAS indices (8). The DMFT/dmft index is a World Health Organization criterion that measures the number of decayed, missing, and filled teeth. The International Caries Detection and Assessment System (ICDAS) is used to detect dental caries at different clinical stages, including early non-cavitated enamel lesions (9). However, neither index provides insights into the oral implications of left untreated caries. To address this issue, Monse et al. introduced the pufa/PUFA index in 2010, which specifically assesses four oral consequences of advanced untreated carious lesions, including exposed pulp, oral mucosal ulceration due to remaining roots, fistulas, and abscesses (10).

In populations with a high prevalence of dental caries among preschool children, a comprehensive understanding of oral health status, including disease severity and its impact on overall health and quality of life, is essential. Although few studies across different populations have reported the negative impact of early childhood caries (ECC) on preschool children's oral health–related quality of life (OHRQoL) (11–16), they were limited by small or region-specific samples. In addition, the existing evidence remains heterogeneous in assessing caries severity and in evaluating the clinical consequences of untreated caries (15). Moreover, nationally representative data integrating comprehensive clinical indices with validated OHRQoL measures are scarce. This large-scale national cross-sectional study investigated the clinical consequences of untreated ECC and their influence on the OHRQoL of preschool children and their families using a validated Arabic OHRQoL instrument (A-ECOHIS). It was hypothesized that greater caries experience and severity, including untreated clinical consequences, would be associated with poorer OHRQoL outcomes. The findings provide strong national evidence that contributes to global understanding of the ECC burden and support the development of preventive and clinical strategies to improve oral health outcomes in preschool children.

The report of this study was developed following the STROBE Statement checklist for cross-sectional studies.

A total of 3,000 kindergarten children enrolled in 22 randomly selected schools across Kuwait's six governorates were invited to participate in the study. Written informed consent forms were obtained from the parents or caregivers of 2,090 children (69.7%). On the scheduled examination days, 307 children were absent. Consequently, 1,783 children received the complete oral examination and were included in the final analysis. A total of 955 questionnaires were collected. Of those, 63 questionnaires had incomplete responses and were excluded, resulting in 892 children who completed both the examination and the questionnaire (Figure 1).

Table 1 presents the demographic characteristics and oral health variables of all participating children (n = 1,783). Of the total sample, 764 were in KG1 (48–59 months), and 1,019 were in KG2 (60–71 months). The gender distribution was nearly equal, with 48.6% males and 51.4% females. The overall caries prevalence was 88.6%, with mean dmft = 6.45 ± 4.5 and mean dmfs = 13.0 ± 14.1. Untreated caries constituted the majority of dmft (dt = 5.68 ± 4.1). Extensive lesions (ICDAS 5–6) were the predominant type (63.4%), and 9.3% of children exhibited clinical consequences of untreated caries, with pulp involvement in 4.8% and abscesses in 3.5% (Tables 1, 2).

Table 3 summarizes the characteristics of the 892 children for whom both clinical and caregiver questionnaire data were available. Of these, 382 were in KG1 and 510 in KG2, with an almost equal gender distribution (50.1% male, 49.9% female). Approximately 18.7% were first-born children, and 23.1% second-born. One-fifth of the children (20.2%) were in the fifth or later birth order. Most fathers (48.8%) and mothers (70.0%) held a diploma/college degree, and only a small proportion of parents had postgraduate education (fathers = 6.8%; mothers = 3.1%). The majority of mothers were aged 25–45 years (95.5%). Almost all parents were married (92.9%). Low father's education was significantly associated with high children's dmft scores (p = 0.035). In contrast, low mother's education was not associated with dmft scores but was significantly related to high pufa scores (p = 0.043). Childbirth order (rank) was associated with both dmft (p = 0.005) and pufa (p = 0.034), with later-born children having higher caries experience and severity. No significant differences were observed by gender.

Based on the 892 valid A-ECOHIS responses (Tables 4, 5), dental pain was the most frequently reported child impact (54.9%), followed by eating difficulties (13.8%), irritability (19.9%), and trouble sleeping (11.5%). Avoidance of smiling (8.0%) and reduced social interaction (7.9%) were less common. At the family level, 34.1% of caregivers reported being upset, 33.1% reported feelings of guilt, and 36.3% had to take time off work due to their child's oral condition. Financial burdens were less frequently reported (17.8%). Children with caries (dmft ≥ 1) exhibited significantly higher ECOHIS scores than caries-free peers (child impact mean 7.65 vs. 4.88, p = 0.02; family impact mean 3.89 vs. 1.65, p < 0.001). Although children with PUFA ≥ 1 and extensive ICDAS lesions showed higher mean ECOHIS scores, these differences did not reach statistical significance in the unadjusted analyses (Table 6).

Multivariable Poisson regression analysis was conducted to examine factors independently associated with child- and family-level OHRQoL after adjustment for potential confounders (Table 7). Caries experience was significantly associated with higher child and family A-ECOHIS scores, indicating poorer oral health–related quality of life (p < 0.001). However, pufa scores were only significantly associated with higher child A-ECOHIS scores, In the adjusted regression model, lower father's educational level, higher birth order, younger child age, and male gender were associated with increased child and family A-ECOHIS scores (p < 0.01).

The present national study provides new evidence on the burden, severity, and clinical consequences of early childhood caries (ECC), as well as its impact on the oral health–related quality of life (OHRQoL) of preschool children and their families. With nearly 9 out of 10 children affected, the prevalence of ECC in this study is among the highest reported globally. The findings reaffirm that ECC remains a major global public health concern, continuing to affect children's overall health and development (10–16).

The high prevalence of ECC, reflected in the high decayed component of the dmft index, indicates insufficient preventive care and early intervention. This finding is consistent with reports from other high-prevalence populations and reflects the continuing global differences in access to preventive and restorative dental care (15, 26–32). The high proportion of extensive lesions (ICDAS 5–6) and the presence of clinical consequences measured by the pufa index demonstrate that untreated caries remains a neglected condition that can lead to infection, pain, and impaired nutrition. Our findings were consistent with previous international reports linking severe dental caries to poor growth and lower body mass index in children (2, 10, 29).

The results of this study confirmed the profound psychosocial problem of ECC. Children with greater caries experience exhibited significantly poorer child and family OHRQoL. However, the contribution of advanced clinical consequences was more evident at the child level than at the family level. Caregivers of the affected children reported higher emotional distress and work disruption. These findings align with numerous studies demonstrating that dental caries negatively affects children's daily performance, eating and sleeping patterns, and social confidence (15, 26–32). The impact on caregivers highlights the broader family aspect of oral diseases, which has increasingly been recognized as an integral component of comprehensive child health (5, 15). The findings support the FDI's global framework that defines oral health as an integral part of overall health and quality of life (33).

From a public health perspective, the associations found between demographic factors and caries experience in this study reflect broader determinants of oral health disparities seen globally. The significant relationship between lower paternal education, higher birth order, and greater caries severity is consistent with findings reported from different populations (34–36). These consistent results suggest that socioeconomic inequalities, family structure, and health literacy remain universal challenges to ECC prevention. Although maternal education was not associated with caries experience, its association with pufa scores may indicate delayed care-seeking behaviors as disease severity progresses (6, 13).

This national dataset thus contributes valuable insight into the global discourse on ECC by providing evidence from a high-income country with universal access to healthcare but persisting high dental caries levels. The coexistence of accessible dental services with widespread untreated caries highlights that the availability of care alone is insufficient without effective early prevention, caregiver education, and community-based behavioral interventions (28). The findings therefore have direct implications for child oral health programs internationally, supporting the WHO and FDI calls for integrated, prevention-focused approaches to reduce the global burden of untreated caries (28, 33).

The study has some limitations. The cross-sectional design restricts causal interpretation of the relationships between ECC severity, OHRQoL, and demographic factors. Despite its nationally representative sample, the exclusion of absent or non-consenting participants may have introduced selection bias. Dental caries was assessed visually without radiographs, in accordance with WHO field protocols (17), which may have underestimated early lesions. Additionally, caregiver-reported OHRQoL data may have been affected by recall or response bias. Minor inter-examiner variability is also inevitable in large-scale epidemiologic surveys despite high calibration levels.

Nonetheless, this study provides nationally representative data from a large sample of preschool children across all six governorates of Kuwait, thereby enhancing the generalizability of the findings to Kuwaiti children attending public kindergartens. These data contribute to the global understanding of early childhood caries as a chronic, behaviorally influenced condition with wide-ranging effects on oral health and quality of life. However, caution is warranted when extrapolating the results to non-Kuwaiti populations or children enrolled in private schools, where socioeconomic and healthcare access factors may differ. The study findings highlight the urgent global need for early, preventive, and family-centered approaches to oral health promotion in preschool children.

In conclusion, early childhood caries had a considerable negative impact on the oral health-related quality of life of preschool children and their families. Caries severity was associated with poorer child oral health-related quality of life but showed no additional impact at the family level. Dental pain and eating difficulties were the most frequent child impacts, while parental guilt and work disruption were commonly reported by caregivers. These findings underscore the importance of early preventive strategies and family-centered oral health programs to reduce the burden of ECC and improve child and family well-being.