Introduction

Despite the decline in tooth decay in the paediatric population throughout the world, dental caries remains the most common childhood disease, causing pain, chewing difficulties, general health disorders, psychological problems and a substantial impact on quality of life [1]. Thus, dental caries is an international public health problem and early detection is important to establishing adequate preventive measures as well as avoiding premature treatment and consequent costs [2–4].

Dental caries has traditionally been assessed using the criteria established by the World Health Organization (WHO) in 1997, which include only obvious carious lesions [5]. However, the detection of lesions in the early non-cavitated stage is important to the diagnostic process [2,6]. An international group of researchers designed the International Caries Detection and Assessment System (ICDAS) in 2007 to allow the assessment of carious lesions in the enamel and active lesions in the dentine. This system is based on the combined knowledge of the clinical appearance of the lesion, whether the lesion is in a plaque stagnation area and tactile sensation (texture) when a round-tipped probe is gently drawn across the surface of the tooth [7,8]. The ICDAS has proven to be reliable, offering increased sensitivity and accuracy in detecting carious lesions, and is indicated for epidemiological surveys involving children [5,9,10].

Despite recent improvements in the oral health of children in Brazil, dental caries remains highly prevalent, with persisting inequalities. The mapping of patterns of oral health in young children and a better understanding of caries initiation and progression are essential to understanding the behaviour of caries as well as determining the best way to control and prevent this disease [11,12]. The detection of early dental caries is one of the most accurate measures for predicting children at a risk for tooth decay [13]. Teeth can develop dental caries as early as three to six months following eruption [14]. Lesion activity at 18 months is related to the incidence of caries at the age of two and three years [15]. Risk factors associated with lesion activity at this age may be related to breast-feeding, bottle feeding, sucrose intake and the absence of tooth brushing performed by a caregiver [15]. Other risk factors include dietary habits, the transmission of pathological microorganisms, especially from the caregiver, oral hygiene habits, family values, traditions and lifestyles [16]. Moreover, the factor nutritional status has not been adequately investigated [17]. Thus, there is a need for a better understanding of the risk factors related to the prevalence of dental caries as well as the best manner to address these factors [4,18].

The assessment of lesion activity is essential to the diagnosis and appropriate treatment [19]. The detection of lesion activity allows the establishment of greater or lesser invasive treatment [20]. From the public health standpoint, minimally invasive treatment reduces treatment costs, as inactive caries can be treated with prophylactic rather than restorative measures [21]. Only one study has used the ICDAS to evaluate lesion activity [22]. However, the study cited was conducted on the permanent dentition. Although studies have assessed risk factors of lesion activity in the primary dentition [15], this is the first study to investigate this association using the ICDAS as the diagnostic criteria for dental caries. While it is expected that the same risk factors exert an influence on dental caries and lesion activity, the lack of previous studies employing the ICDAS for the primary dentition justifies the present investigation.

The aim of the present study was to determine factors associated with dental caries and lesion activity in the primary dentition using the ICDAS as the diagnostic criteria.

Materials and Methods

Results

Eight hundred forty-three pairs of parents/guardians and children took part in the present study. The response rate was 97.56%. The loss of 21 pairs was due to the non-participation of the child for medical reasons (n = 1), incomplete questionnaires (n = 10), absence from preschool on the days scheduled for the clinical examination (n = 5) and a lack of cooperation during the examinations (n = 5).

Boys accounted for 51.7% of the sample and girls accounted for 48.3%. The children were balanced by age: 32.6% were three years old, 39.6% were four years old and 27.8% were five years old. The majority of mothers (53.8%) had more than eight years of study. Fifty-five percent of families had a monthly household income greater than or equal to US$ 312.50. The vast majority (84.4%) of families had less than six residents in the home. A total of 31.3% of the participants were the only child in the family, 41.6% were the youngest child, 14.7% were the oldest child and 12.4% were the middle child. A total of 45.9% were enrolled at private preschools and 54.1% were enrolled at public preschools (Table 1).

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Table 1. Sample characterisation.

https://doi.org/10.1371/journal.pone.0150116.t001

The prevalence of dental caries was 66.3%. Among the children with caries, 88.0% had active lesions (Table 1). Among the teeth with dental caries, 24.0% were non-cavitated (score of 2), 76.0% were cavitated (scores 3 to 6) and 63.0% were severely cavitated (scores 5 and 6).

Table 2 displays the logistic regression for predictors of dental caries. In the final model, the girls (OR = 1.53, 95% CI: 1.05 to 2.23; effect size: 0.06), mother’s schooling ≤ 8 years (OR = 1.55, 95% CI: 1.07 to 2.23; effect size: 0.15) and monthly household income ≤ U$ 312.50 (OR = 2.38, 95% CI: 1.65 to 3.43; effect size: 0.20) were significant predictors of dental caries.

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Table 2. Logistic regression model considering design effect (unadjusted and adjusted odds ratio) for dental caries and independent variables among children aged 3 to 5 years (OR, 95% CI).

https://doi.org/10.1371/journal.pone.0150116.t002

Table 3 displays the logistic regression for predictors of lesion activity. In the final model, only mother’s schooling ≤ 8 years (OR = 2.15, 95% CI: 1.15 to 4.00; effect size: 0.10) was significant predictor of lesion activity.

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Table 3. Logistic regression model considering design effect (unadjusted and adjusted odds ratio) for lesion activity and independent variables among children aged 3 to 5 years (OR, 95% CI).

https://doi.org/10.1371/journal.pone.0150116.t003

Discussion

The present school-based study sought to identify possible determinant factors associated with the presence of dental caries and disease activity in preschoolers using the ICDAS as the diagnostic method. Studies have used the WHO criteria for the diagnosis of dental caries diagnosis [29–31], which do not discriminate initial carious lesions or lesion activity. In the present study, mother’s schooling was the only risk factor for both dental caries and caries activity in preschool children.

The population studied had a high prevalence rate of dental caries (66.3%), which means that only one third did not need treatment beyond preventive measures. Moreover, 63% of the children with caries had severe degrees of the disease, such as a distinct, extensive cavity with visible dentine [7]. Such results indicate that these children needed some kind of operative dentistry. However, the mere diagnosis of dental caries does not indicate caries activity. Thus, the determination of lesion activity allows differentiating children in need of dental treatment from those not in need of treatment. Among the entire sample, 58.4% (492 children) needed some type of treatment (active dental caries in enamel or dentine). Not all active lesions in enamel will progress to more severe degrees and many may go into remission. Such lesions can be treated conservatively with fluoride therapy. On the other hand, if not treated, active lesions in enamel may progress to the dentine and require restoration. Moreover, active lesions in the dentine cannot go untreated due to the risk of severe complications, which occur in approximately 40% of cases [14]. Active cavitated lesions in the dentine can involve the pulp and require endodontic treatment or extraction, which are more complex procedures. Moreover, controlling caries at this point implies efforts beyond operative dentistry, such as sugar control, fluoride treatment, a change in habits and family involvement.

Girls had a greater likelihood of having dental caries, which is in agreement with findings described in previous studies [32,33]. This may be explained by the earlier eruption of teeth in girls, with a consequent longer exposure to cariogenic factors in the oral environment [34]. Otherwise, sex was not associated with lesion activity. The exposure to fluoride may play a role in the remineralisation of dental caries equally in both sexes.

Dental caries and lesion activity had one common risk factor in the present investigation: mother’s schooling. Theses associations may be explained by a greater offer of sweets and diets with sugar by mothers with a lower level of schooling [35] and a lack of knowledge regarding the influence of diet on the progression of dental caries [12]. Moreover, household income was a significant predictor of caries, which is in agreement with findings reported in the literature [16,35,36]. This underscores social inequalities with regard to dental caries, the prevalence of which is higher among individuals with a low income and low level of schooling, confirming that individuals with a low socioeconomic status are more exposed to a various risk factors that affect oral health [37,38]. The association between lesion activity and income should be studied in other populations.

Differences among social classes constitute a huge problem in Brazil, where a large portion of the population has a low income and the minority is rich. Median monthly household income was equivalent to U$312.50 (the minimum wage in Brazil). Only 50% of the sample earned more than the minimum wage and income distribution was very irregular. This shows that a large portion of the children lived in families with a low income and their mothers had a lower education level, which may explain the high prevalence rates of dental caries and lesion activity and also underscores social inequalities with regard to these outcomes.

One problem regards the percentage of children not enrolled at preschools. Among the 22,440 children aged three to five years in the city of Campina Grande, 12,705 were enrolled at preschools. This problem is common throughout Brazil. If the remaining children were considered in the prevalence study of dental caries, the frequency would have been much greater than that presented herein.

This study has limitations that should be addressed, such as information bias regarding income and memory bias, which is a common occurrence when data are collected retrospectively. Another limitation regards the lack of the detection of the first visual change in enamel (ICDAS code 1) [36], which may have underestimated the prevalence of dental caries. Moreover, no dietary histories of the patients through diet recalls were taken.

The prevalence rates of dental caries and lesion activity were high in the present sample. A low level of mother’s schooling was a common risk factor for both outcomes, whereas a lower income and the girls were risk factors for dental caries. In Brazil, there is a lack of specialized care for infants and preschoolers at public health services [39]. Thus, current oral health policies are inadequate. The present findings highlight the need for policy revision to include early childhood in preventive dental strategies and define appropriate prevention approaches. Other authors report that counselling mothers in the initial days following the birth of a child regarding oral health care, with the presentation of educational material, is an effective approach to improving oral health in preschool children [31].

Supporting Information