Factors associated with the development of dental caries among schoolchildren in northwest Mexico

1. Introduction

Dental caries rank as the most prevalent oral health disease among school-age children worldwide, posing a significant public health problem [1, 2, 3]. According to the global oral health report published by the World Health Organization (WHO) in 2022, oral diseases affect approximately 3.5 billion people around the world. Global estimates indicate that two billion people experience caries in their permanent teeth and 514 million children in their primary teeth [2]. This condition causes dental pain and discomfort, impairs childhood functions including language development and imposes a financial burden on families [4, 5, 6]. In children and adolescents, caries constitute a multifactorial disease whose prevalence and incidence in populations are determined by numerous risk factors including age, ethnicity, dietary patterns such as sugar consumption, oral hygiene habits, and socioeconomic level [7, 8, 9].

In 2021, a study conducted by the Mexican Ministry of Health obtained a value of 3.69 in the Decayed, Missing and Filled Primary Teeth (dmft) index for girls and boys aged 2–10 years, from a socially marginalized community [7]. Meanwhile, Kolawole et al. [8] reported a dmft index of 0.27 for 6–12-year-old schoolchildren from a disadvantaged population in Nigeria, stating that 14.9% of participants suffered from dental caries.

The Mexican study cited above yielded a value of 3.2 in the Decayed, Missing and Filled Permanent Teeth (DMFT) index for children and adolescents aged 6–19 years [7], while the study conducted in Nigeria and a similar research in Saudi Arabia reported DMFT indices of 0.39 and 7.8, respectively [8, 9]. The Mexican study estimated dmft and DMFT indices of 3.36 and 2.97, respectively, in the state of Sinaloa, in northwest Mexico [7]. Additionally, Prada et al. [10] reported a global DMFT Index of 4.48 for 6–12-year-old schoolchildren from underprivileged areas of Valencia, in Spain.

Regarding prevalence, the study by the Mexican Ministry of Health analyzed children and adolescents 2–19 years old, yielding rates of 75.4% nationwide and 65.4% in the state of Sinaloa specifically [7]. Similarly, Prada et al. [10] found a prevalence of 81.87% in Valencia. Another Mexican study by Casanova and Medina revealed that caries were far more common in primary than in permanent teeth, with a prevalence of 73.6% and a dmft index of 2.85 [11]; a study by Lara-Capi demonstrated that participants from low-income households in Veracruz, Mexico, were 2.21 times as likely to present cavitated caries lesions as those enjoying medium and high socioeconomic levels [12], and a study by Contreras-Bulnes conducted with street children in Toluca, in central Mexico, reported a prevalence of 59.08% in primary teeth, with a dmft of 3.50 [13].

According to Prada et al. [10], the presence of cavitated caries is also associated with mothers’ educational levels and poor oral hygiene including low brushing frequency. Studies conducted in Chile, Mexico and Saudi Arabia identified more prevalent and severe cases of dental caries among children from low-income families who attended public schools, compared to their counterparts in more favorable settings. These children were raised in contexts calling for preventative measures and adequate restorative care in oral health services [14, 15, 16, 17]. Over the last 20 years, the prevalence of caries has decreased in high- and upper-middle-income countries, while increasing in low- and lower-middle-income countries [18].

Various studies have addressed the risk factors affecting dental caries. They show that unhealthy—particularly high-sugar and low-fiber—diets are associated with overweight, obesity, nutrient deficiency and dental caries in children [12, 19, 20]. Furthermore, it has been demonstrated that the interaction between the frequency and quantity of sugar consumption is significantly associated not only with an increase in the experience and prevalence of caries [21], but also with a greater risk of infection [22, 23]. Other determining factors reported include oral hygiene habits, education, the social environment and economic conditions that limit access to health services [24].

The purpose of this study was to identify the risk factors for dental caries such as diet, hygiene practices and the specific sociodemographic variables of a school population in an urban area of northwest Mexico. We anticipated that our findings could provide useful guidelines for conducting longitudinal studies to explore the ways in which these factors are dynamically associated with the prevalence of dental caries over time. This, in turn, would contribute to adapting intervention strategies that fit the needs of specific populations.

2. Material and methods

We conducted a cross-sectional, descriptive study with schoolchildren between the ages of 6 and 12 years, from 28 of the 49 public elementary schools in the city of Culiacan Rosales, the state capital of Sinaloa (N = 14,852). In calculating sample size, we considered the following criteria: a proportion of 73% [25] a precision of 1.5%, a non-response rate of 5% and 95% confidence interval. The calculated sample totaled 3304, and the final sample, 3275 schoolchildren. Authorization to carry out the study was requested from the authorities of the Ministry of Public Education and Culture in Sinaloa, and from the director of each school selected.

Sampling was based on a stratified multistage cluster and simple random probability design. Selection probability for each school was proportional to the total number of students, and the number of schools visited per stratum was proportional to the total number of students in the stratum.

The clusters were comprised of five zones (center, northwest, northeast, southeast and southwest) geographically located in Culiacan. The sites of the 49 schools were distributed as follows: 13 schools (25.87%) in the center, 12 (25.00%) in the southwest, 6 (10.71%) in the southeast, 9 (17.86%) in the northeast and 9 (17.86%) in the northwest of Culiacan.

Our sample of 28 schools (strata) was distributed in proportion to the number of schools in each zone: eight schools were selected from the center, seven from the southwest, three from the southeast, five from the northeast and five from the northwest.

Each school was assigned a sample size of 118 schoolchildren to be examined: 108 from 6–11 and 10–12 years old. Allocation by sex was determined for each school as follows: nine boys and nine girls from the 6–11 age group, and five boys and five girls from the 12-year age group. Selection was random, taking the school enrolment list as our sampling frame.

3. Results

The study was carried out in 28 of 49 public elementary schools in Culiacan. Of the calculated sample (3304 participants), the final response rate reached 99.12% (the 0.88% loss was attributable to our elimination criteria and the refusal of some parents to participate in the study). Our final sample thus totaled 3275 schoolchildren.

Table 1 illustrates the sociodemographic characteristics of the study population. The participants were evenly distributed by sex (50.6% female vs. 48.4% male) and their ages averaged 8.5 (standard deviation—SD ± 1.74 years). For the purposes of the binary statistical analysis, we dichotomized the age variable into two groups: 6–9 years (65.6%) and 10–12 years (34.4%). Regarding the participants’ families, 83.9% of the students belonged to households consisting of 2–4 members; the average age of the fathers slightly exceeded that of the mothers (38.87 vs. 35.97), with the former reporting high-school studies and above, a higher educational level (75.9%) than that of the mothers (55.0%). Regarding Social Security insurance, 16.3% of the families had no coverage and 17.2% had attended at least one preventative dental appointment within the last year. In assessing the socioeconomic indicators based on ownership of household assets, we found that 37.38% of the families fell into the first, or lowest, tercile, while 33.3% occupied the third or highest, tercile. Finally, as regards their monthly household living expenses, 28.3% of the families lay in the third and 25% in the first tercile.

4. Discussion

This study identified key factors that predispose individuals to developing caries in primary and permanent dentition. In a previous study conducted in Mexico, Villalobos et al. [30] found that schoolchildren who presented caries during their primary dentition were nearly three times as likely (OR = 2.93) to experience caries in their permanent dentition as those who did not. Similarly, our study indicated that the presence of caries in the primary dentition was associated with developing caries in the permanent dentition (adjusted OR = 2.53, p < 0.001).

Regarding age, the present study, which analyzed schoolchildren aged 6–12 years, found that older children (ages 10 to 12) were less likely to have had caries in their primary dentition (adjusted OR = 0.53, p < 0.001), but were more likely to have caries in their permanent dentition (adjusted OR = 1.98, p < 0.001). This association between older children and the presence of caries in permanent dentition has been described in the Mexican population [16, 30].

In Romania, a greater prevalence of caries was observed among schoolchildren who drank soft drinks and chewed sugary gum [31], while in Saudi Arabia, caries prevalence was also correlated with sugar consumption (p < 0.05) [9]. Furthermore, in Taiwan, schoolchildren who frequently consumed sugar-rich beverages faced a significantly higher risk of developing caries than those who rarely consumed such beverages (p = 0.017) [31].

The preceding results are in line with the findings of our study, which indicated that the consumption of chocolates, sweets, pastries and cookies was associated with a higher risk of developing caries in primary dentition. Accordingly, Al-Ansari [32] has proposed that dentists encourage reducing the intake of ultra-processed food and sugary drinks, as well as adopting a balanced and healthy diet.

As regards toothbrushing, Prada [10] reported that, among schoolchildren aged 6–12 years in Spain, a significant association was observed between the presence of caries and brushing frequency, as well as between brushing frequency and having attended dental consultations: those who had been to the dentist brushed their teeth more often compared to those who had not. In Ecuador, Fernández et al. [33] correlated the number of brushes per day with the DMFT index in 12-year-old schoolchildren, and found an inverse correlation, with the SiC yielding a value of p = 0.029. We found that initiating toothbrushing after two years of age was a risk factor for developing caries in both primary and permanent dentition.

As to the reasons motivating 12-year-old schoolchildren in Romania to attend a dental consultation in the previous 12 months, Sfeatcu et al. [18] reported that 43.1% cited dental pain as an indication of a dental emergency. Furthermore, Alshammary et al. [9] reported that, among schoolchildren in Saudi Arabia, 45.1% visited clinics because they had experienced dental pain, while only 15.3% went for a checkup. Our study highlights the importance of preventative consultations as a protective factor against developing caries in primary (OR = 0.64, p < 0.001) and permanent (OR = 0.80, p = 0.11) dentition.

The above-mentioned study in Saudi Arabia noted that the educational level of parents correlated with the prevalence of caries in schoolchildren [9]. Díaz et al. [34] conducted a study in Colombia in order to describe the interaction of the prevalence and severity of caries in schoolchildren with family factors. They found a statistically significant correlation between fathers dropping out of middle school and the development of caries in their children (p = 0.04). Similarly, our study found that a low educational level (through middle school) on the part of mothers was positively associated with the presence of caries in the primary dentition of their children, as well as in their permanent dentition during adulthood. Likewise, a low level of education on the part of fathers constituted a risk factor for caries in the primary and permanent dentitions of their children. Along these lines, Minervini et al. [35] reported that, in Italy, both parents having a low educational level could negatively affect the oral health status of their children. For the authors, a clear relationship existed between the educational level of parents and their ability to prevent their children from engaging in unhealthy behavior.

In addition to the above, Casanova et al. [11] reported that 6–13-year-old Mexican children of low socioeconomic level were more likely to develop caries than those enjoying medium and high socioeconomic levels (OR = 1.38). Our study also found that a high socioeconomic position, as determined by ownership of household assets, was a protective factor against developing caries in primary (adjusted OR = 0.68, p < 0.001) and permanent (adjusted OR = 0.66, p < 0.001) dentition.

In Australia, a high family income correlated with fewer caries among schoolchildren, regardless of dentition or educational level [36]. We found that higher monthly household living expenses constituted a protective factor for caries in primary dentition (adjusted OR = 0.75, p = 0.002), while not having Social Security coverage was associated with caries in both dentitions (OR = 1.27, p = 0.01; OR = 1.12, p = 0.38).

This study had several important limitations. The first was a possible self-reporting bias which could have affected the validity of our results. The second pertained to the use of a cross-sectional survey. This method is characterized as being temporally ambiguous as a result of the exposure-effect association, making it impossible to establish causality. Additionally, the population sample was drawn from a single city in the state of Sinaloa, which might have affected the generalizability of the results. Nonetheless, the evidence provided can be useful in designing oral health initiatives for other urban schoolchildren comparable to those in our sample. Finally, the use of the WHO criteria did not consider caries in their early stages, possibly resulting in an underestimation of their prevalence. The study also had several strengths. These included the flexibility to explore associations between multiple exposures and effects, considering the demographic, socioeconomic and clinical variables of a representative population sample in the locality analyzed. This contributed to generating useful data for the planning and management of health services.

5. Conclusions

The presence of caries in primary teeth is positively associated with the presence of caries in permanent teeth, with preventative dental consultation representing a protective factor for caries in both dentitions. To reduce the development of caries at both stages of dental development, it is essential that dental professionals promote preventative education regarding correct oral hygiene, healthy nutrition, and dental check-ups from an early age.

Availability of data and materials

The data analyzed in this study are available upon request. Please write to the corresponding author.

Author contributions

JJVR and RAGJ—designed the study. CMUB, MVGJ, CAMC, GEGC and JJVR—conducted the study. RAGJ, VGGG and AKOV—provided support and advice in oral epidemiology. CAMC, JJVR and CMUB—contributed to data collection and analysis. CMUB, AEVU and EMT—wrote the manuscript. All authors made editorial revisions to the manuscript. All authors have read and agreed to the published version of the final manuscript.

Ethics approval and consent to participate

This study was conducted in conformity with the Declaration of Helsinki, and was ethically approved by the Research Project Coordination Department at the Autonomous University of the State of Sinaloa (601-ASC107658). Participant assent was obtained from the schoolchildren and written informed consent from their parents/guardians for participation in the study. All were assured that the information gathered would be treated in a confidential manner.

Acknowledgment

We thank the Ministry of Public Education and Culture in the State of Sinaloa for supporting our work. We are particularly grateful for their access to the data required and for facilitating our communication with the management staff of participating schools.

Funding

This research received no external funding.

Conflict of interest

The authors declare no conflict of interest.