Early childhood caries is a significant public health problem due to its high prevalence in economically disadvantaged groups.1 Factors such as consumption of sugary foods, dental plaque accumulation, and number of people in the household have been found to be associated with caries.2,3

Few studies have evaluated oral health and socioeconomic disparities in preschool children in Latin American countries.4,5 In Chile, efforts have been made to diminish health disparities (e.g., water fluoridation programs). Nevertheless, the caries distribution associated with socioeconomic, dietary and oral hygiene factors has not been described for preschool children.

We aimed to identify factors associated with caries extent and estimate the prevalence of caries among preschool children in southern Chile.

The final sample size was 1,387 two-year-old children and 1,600 four-year-old children. The response rate was 75.4% and 76.2% respectively. A total of 65.7% of the 2-year-olds and 59.1% of the 4-year-olds were from families with low socioeconomic position. The socioeconomic position distribution was similar between regions (data not showed). The highest educational level reported by 65.4% of the 2-year-olds’ caretakers and 63.8% of those of 4-year-olds was secondary school or less.

Caries prevalence in 2-years-olds was 20.3% and 52.7% in 4-year-olds. In both groups, the prevalence of caries was lower as the household's socioeconomic position category was higher (Table 1).

The mean dmft was 0.6 in 2-year-olds (95% confidence interval [95%CI]: 0.5-0.8). In this group, the mean number of decayed teeth was 0.6 (95%CI: 0.5-0.7) and mean number of filled teeth was 0.0 (95%CI: 0.0-0.1). No extractions were found. The mean dmft was higher in children from low socioeconomic position households than in those from high socioeconomic position households (Table 1). No statistically significant differences between boys and girls were found for the dmft index (p-value for U Mann-Whitney test was 0.097).

In 4-year-olds, the mean dmft was 2.5. This group had a mean number of decayed teeth of 2.0 (95%CI: 1.7-2.4), mean number of filled teeth of 0.4 (95%CI: 0.3-0.6), and mean number of extracted teeth of 0.0 (95%CI: 0.0-0.1). The mean dmft was 3.2 in 4-year-olds from low socioeconomic position households, compared with 0.6 in those from high socioeconomic position households.

The SiC index was 1.8 for 2-years-old children and 6.0 for 4-years-olds. In both age groups, children from low socioeconomic position households had higher SiC indexes than children from other socioeconomic position households.

Table 2 shows the results obtained from the multivariable model for dmft. For 2-year-old children living in the Bio-Bío region, the dmft was 1.65 times larger than it was for those living in the region of Aysén-Magallanes, whereas for 4-years-old it was 1.44 times as large. Children in low and middle socioeconomic position households had a significantly larger dmft index than those in higher socioeconomic position households.

Four-year-old children who drank sugary beverages before bedtime with high frequency had a dmft 1.30 times as large as those who drank before bedtime less than 3 times per week. Four-year-olds who did not brush their teeth daily had a dmft 1.37 times larger than those who brushed their teeth daily. In this age group gingivitis was associated with the dmft index (PR=1.64).

Our findings reveal a high prevalence of dental caries in the preschool children in Chile. Countries such as the United States9 and Brazil4 have reported lower caries prevalences among comparable populations. Despite these differences, caries showed a similar distribution pattern among socioeconomic levels as described in other studies.4,9 It is important to note that the dental caries index used for this study followed the guidelines of the WHO,6 which does not differentiate between stages of development of dental cavities. This situation might underestimate the caries prevalence in this population.

The mean dmft in 4-year-olds was lower than that reported in similar studies in Chile,10 but higher than that reported in similar populations in other Latin American countries11 and indicates considerable oral damage due to caries. Health disparities can be further understood with the SiC index which showed that children in low socioeconomic position households had extensive caries experience.

The multivariable and descriptive analyses confirmed large-scale inequalities in socioeconomic position in both age groups, which is consistent with the literature describing older children.1,12 These inequalities are reflected in the descriptive results, which showed that 2 year old children of low socioeconomic groups had 10 times more caries than those of higher socioeconomic groups. Also the multivariable model showed a prevalence ratio of caries in children of low socioeconomic groups of at least twice that of higher socioeconomic groups. On the other hand, nutritional factors contributed independently to caries prevalence. We hypothesize that these behaviors replaced previous behaviors also associated with nighttime feeding at earlier ages. Oral hygiene habits were found to be protective factors at age 4 which might be due in part to increased motor control,13 and their increased ability to understand instructions.14 Other factors such as parents educational level and dental education in daycare centers might also affect oral hygiene among individuals, but they could not explain the difference between ages. The higher risk of developing caries in the region of Bio-Bío could be explained by the extremely low levels of fluoridated water in this area (0.003 to 0.055ppm).15

Our results showed that there were no statistically significant differences between boys and girls in the number of carious lesions. The literature regarding this topic for this age group is scarce and not conclusive.16

The study limitations are that all sampled children attended daycare facilities, affecting the results’ external validity; also the cross-sectional study design emphasizes the need to be cautious with the interpretation of its results. It is important to consider that nutritional and oral hygiene variables might be influenced by oral health status and therefore we cannot establish these as risk factors for dental caries.

On the other hand, the strength of this study relies on the sample size and on the heterogeneity of the sample in terms of geographical distribution, family characteristics, and type of daycare centers (public without out-of-pocket charges, subsidized, and private).

In conclusion, this study found a high caries prevalence in children at very young ages in this region of Latin America. Socioeconomic position was found to be associated with caries experience. Nutritional habits were associated with caries development in all children, independent of their socioeconomic status and region of residency. We suggest that other factors such as family traditions might be related to dietary habits in this population. We encourage the implementation of oral health education and prevention programs aimed at improving nutritional habits at a familial level so that children can experience a healthy home environment.

Glòria Pérez.

The corresponding author on behalf of the other authors guarantee the accuracy, transparency and honesty of the data and information contained in the study, that no relevant information has been omitted and that all discrepancies between authors have been adequately resolved and described.

L. Hoffmeister and P. Moya were involved in the conception and design of the work. C. Vidal carried out the analysis and interpretation of data. D. Benadof contributed to the writing and its critical review with important intellectual contributions. All authors have approved the final version and are jointly accountable for all aspects of the work.

The Ministry of Health of Chile contributed to the accomplishment of this work.

None.