Children's rapid physical growth in their first three years coincides with primary teeth eruption and weaning, suggesting a link between nutrition, growth, and oral health. Underweight, a key malnutrition indicator, is prevalent in rural Cambodian children, possibly due to socioeconomic status and dietary practices. Cambodia has a high prevalence of underweight children, with malnutrition being a leading cause of death in children under five. Early childhood caries (ECC) is also highly prevalent in Cambodia, with a substantial proportion of children affected even before all primary teeth erupt. Previous studies have highlighted the poor oral health of young Cambodian children and the need for integrated general and oral health approaches. While some Asian studies have linked body weight and oral health, research in Cambodia on this association, particularly in young children, is limited. This study aimed to investigate the association between underweight and oral health factors among children aged one to three years in rural Cambodia.

Existing literature indicates a strong correlation between malnutrition and underweight in children, particularly those from rural areas. Several studies have shown a higher prevalence of underweight children in Cambodia compared to other countries, with malnutrition being a significant contributor to child mortality. The prevalence of early childhood caries (ECC) is also alarmingly high in Cambodia. Studies in Kampong Cham province show a high percentage of children developing ECC by two years old. The lack of dental treatment is widespread, and poor oral health has been linked to various associated factors. Previous research suggests an integrated approach combining general and oral health is crucial to address these issues. Studies in Asian countries have shown a link between body weight and oral health, with underweight children being more likely to have severe dental caries. However, limited research focuses on this association in young Cambodian children.

This cross-sectional study involved 200 Cambodian children (111 males, 89 females; mean age 27.00 ± 9.41 months) aged one to three years from several villages in Steung Trang district, Kampong Cham province. Children with less than eight erupted teeth were excluded. Data were collected from May 2018 to January 2019 at the Khpob Ta Nguon Health Center. Underweight was assessed using weight-for-age Z-scores from the WHO Child Growth Standards, categorizing children as moderately underweight (below -2SD) and severely underweight (below -3SD). Nutritional status was evaluated using mid-upper arm circumference (MUAC), with <12.5 cm indicating malnutrition. ECC was assessed using WHO Oral Health Surveys Basic Methods, with intra-examiner calibration yielding a kappa score of 0.87. Information on socio-demographic factors, child-rearing practices (breastfeeding, bottle-feeding, dietary habits, oral hygiene), birth weight, and current weight were collected through interviews with caregivers. Statistical analysis used Chi-square tests to assess associations between variables and weight status, and logistic regression to determine predictors of underweight, adjusting for sex, age, and number of erupted primary teeth. A p-value < 0.05 indicated statistical significance.

The study found a high prevalence of underweight (33.5% moderately underweight, 7.0% severely underweight) and ECC (61.5%) among the children. The prevalence of moderately underweight children significantly increased with age (P<0.05). Children with low birth weight (<2500g; 15.2%) were significantly more likely to be moderately and severely underweight. Children with malnutrition (MUAC <12.5cm; 5.1%) were also significantly more likely to be underweight. ECC was significantly associated with moderate underweight (P<0.05). Logistic regression analysis revealed that low birth weight (OR=2.57; 95% CI 1.03-6.40) and malnutrition (OR=4.71; 95% CI 1.08-20.62) were significant predictors of moderate underweight. Low birth weight (OR=10.68; 95% CI 2.95-38.65) and ECC (OR=6.67; 95% CI 1.02-43.61) significantly predicted severe underweight. While more frequent sugary beverage intake was associated with moderate underweight (P<0.05), other child-rearing practices showed no significant associations with underweight status.

This study highlights the significant association between underweight and ECC in young children in rural Cambodia. The high prevalence of underweight, increasing with age, mirrors findings from other developing countries. Low birth weight, a strong predictor of underweight, is prevalent in the study population, potentially linked to factors such as low maternal education and socioeconomic disadvantages. Malnutrition, as indicated by low MUAC, further contributes to underweight. The strong association between ECC and underweight, particularly severe underweight, warrants attention. Untreated ECC can lead to pain, reduced dietary intake, and financial burdens on families, potentially exacerbating underweight. The findings underscore the need for integrated interventions addressing both malnutrition and oral health, including promoting optimal breastfeeding practices, healthy weaning, and oral hygiene. The study's limitations include potential selection bias and the cross-sectional design, which prevents establishing causality.

This study reveals high prevalences of underweight and ECC among young children in rural Cambodia, both increasing with age. Low birth weight, malnutrition, and ECC are significant predictors of underweight. Comprehensive health and nutrition programs targeting children during the weaning period are crucial to address these issues. Future longitudinal studies are needed to clarify the causal relationship between ECC and underweight and to evaluate the effectiveness of integrated interventions.

The study's limitations include potential selection bias due to the inclusion of only children attending health check-ups, potentially representing a healthier subset of the population. The cross-sectional design limits the ability to establish causal relationships between ECC and underweight. The small sample size and focus on a single rural area restrict the generalizability of findings to the broader Cambodian population. Future research should address these limitations using larger, longitudinal studies in diverse settings.