INTRODUCTION

Dental caries is a multifactorial disease that basically depends on three fundamental factors: the presence of cariogenic bacteria, a substrate, and a susceptible host ¹ . Currently, the disease is characterized as a mineral loss of the tooth structure due to acids produced by bacterial metabolism and, consequently, a drop in pH and demineralization of the dental tissue ² .

At the beginning of the 21st century, dental caries continues to be classified as the main oral health problem, affecting 60 to 90% of school children and most adults. The disease is one of the main causes of tooth loss and toothache, limiting activities at work and school, and thus affecting the general quality of life of those affected ³ .

The most recent national data on dental caries, from 2010, showed that at five years of age, only 46.6% of Brazilian children were free of caries in their primary teeth and at 12 years of age, only 43.5% were free of caries in their permanent teeth ⁴ .

In Brazil, the prevalence of caries in 12-year-old children fell from 96.3% to 68.9% between 1980 and 2003, reaching 56% in 2010, mainly due to the use of fluoridated toothpaste and water ⁴ .

Dental caries can cause suffering and pain in people, and is considered a public health problem ⁵ . Both caries and periodontal disease are the most prevalent oral diseases from a public health perspective, thus causing a major impact on individuals’ quality of life ⁶ .

The occurrence of caries can be influenced by socioeconomic factors, demographic, behavioral, biological and clinical conditions, where avoiding dental treatment is one of the main reasons for the compromise of oral health ⁷ . This can also be influenced by environmental factors and lifestyle ⁸ .

There is evidence that the distribution of caries in populations is uneven and commonly associated with socioeconomic status ⁵ . Low income, associated with difficulty in accessing hygiene products, is associated with the severity and prevalence of dental caries ⁹ .

Dental caries and gingivitis have dental biofilm (bacterial plaque) as an important common etiological component, where dental biofilm can be understood as a diverse community of microorganisms that develops on the tooth surface ¹⁰ .

Adolescents have the best general health indices, but when related to their oral condition, this age is considered a difficult phase ¹¹. When we consider the consumption of sugary foods and the poor control of biofilm, adolescence can be characterized as a period of risk for oral health ¹² . Kaewkamnerdpong and Krisdapong ¹³ highlight that the daily consumption of sweets by children and adolescents is positively associated with the sales of sugary foods and beverages in schools, and state that the creation of environments that support oral health in schools is an important strategy to promote oral health at school age.

The objective of the present study is to verify the prevalence of dental caries in adolescents from two schools in the city of Nova Araçá – Rio Grande do Sul, to know the average DMFT index and compare it among the students.

METHODOLOGY

This research followed the guidelines of Resolution No. 466/12 of the Health Council and the approval of the Research Ethics Committee (CEP) of the Faculdade Meridional IMED, being approved by the same number 2,014,434. All adolescents and parents/guardians signed the Free and Informed Consent Form and the Assent Form accepting to participate in the research.

Study design and sample

This study is an epidemiological survey with a quantitative approach of the descriptive and prevalence type, whose sample was the total number of students enrolled in two schools in a municipality, considered as a census. Thus, the sample totaled 132 students aged 11 to 13 years old, students from private and state schools located in the city of Nova Araçá, in the Encosta Superior region of the Northeast of Rio Grande do Sul, composed of a population of 4,429 inhabitants, distributed in an area of ​​74.704 km ¹⁴ .

Procedures and instruments for data collection

For data collection, a questionnaire with questions related to age (11, 12 and 13 years old); sex (female and male); whether they have ever been to the dentist (yes or no); school attended (private and state); brushing frequency (once a day, twice a day, or three or more times a day); mother’s education (elementary school, high school, or college): mother works outside the home (yes or no); lives in urban or rural areas; frequency of consumption of sugary drinks (no drinks, one to two drinks per day, or three or more drinks per day); type of drink (soda, juice with sugar, or both); frequency of consumption of cookies per day (none, once to twice a day, or three or more times a day); and type of cookie/cracker (filled or not).

Data collection was carried out in November and December of 2016 in the morning and afternoon shifts. The questionnaires were completed by the students in their classrooms with the presence of the researcher and a teacher to assist with logistics and organization.

Subsequently, a clinical examination was performed to collect data on dental caries using the DMFT index (index of decayed, missing and filled teeth), subdivided into C (decayed), P (missing), O (filled) and the unit measurement, D (tooth), which was proposed by Klein and Palmer (1937). ¹⁵ The biofilm was collected from the visual examination with a wooden spatula on the vestibular surface of the upper anterior teeth (elements 11, 12, 21 and 22). The clinical examinations were performed before snack time, in order to verify the presence of biofilm before the food provided in the schools. The evaluator calibration process verified the level of intra-examiner agreement for the use of the DMFT index, and the evaluator underwent prior training. The SB 2000 Calibration Instruction Manual ⁴

was used for the theoretical reference . The result of the Kappa coefficient test generated a value of 0.94 (p<0.001), which is considered excellent agreement. A descriptive statistical analysis was performed to describe the relative and absolute frequencies of all variables using the Statistical Package for the Social Sciences (SPSS) version 20.0. RESULTS Table 1 describes the data related to the variables of the students, with the predominant age being 12 years (47.6%), and the majority being students of the state school system (72.4%). It is also possible to observe that the vast majority (93.3%) of the students had already been to the dentist. The presence of biofilm on the teeth was detected in the vast majority (86.7%).

The amount of soft drinks consumed daily by schoolchildren is 62.8%, and some also drink sugary juice in addition to soft drinks (43.8%). The frequency of schoolchildren who eat cookies 1 to 2 times a day is 98.1%. Of these, 30.5% eat filled cookies and 39% eat them with and without filling (Table 1).

The total average DMFT index of schoolchildren was 1.22 ( SD 0.34), with a minimum value of 0 and a maximum value of 6 (Figure 1).

The average dental caries rates of the schools were 1.14 and 1.25, respectively for Private and State schools (Table 2), with no statistically significant difference between the average DMFT index of the students (p=0.66).

When the DMFT components were analyzed separately, it was found that the presence of dental caries was 39% and in restored teeth with caries it was 5.7%. Thus, the total prevalence of untreated dental caries is 44.7%. Figure 2 shows the frequencies of the DMFT components (decayed, restored without caries and restored with caries).

DISCUSSION

When the mean DMFT index of the sample analyzed was investigated, the data showed low caries rates. However, when the components of the DMFT index were analyzed separately, there was a high prevalence of untreated caries in the schoolchildren investigated. The study found a mean DMFT of 1.22, which corresponds to low caries severity, similar to the results found in the city of Ponta Grossa-PR, where the mean DMFT was 1, considered very low ¹⁶ .

Contrary to the results of previous studies, a moderate DMFT index of 3.38 was found in 12-year-old schoolchildren in a city in the same region as the present study ⁷ . However, this city is larger, which may have influenced the higher value of the index. Similarly, in other states, such as Rio Claro in the state of São Paulo, the index found was 2.71 ¹⁷ and in Araucária in Paraná, the average was 2.4 ¹⁸ .

The prevalence of untreated caries in the present study was 44.7%, which is similar to the study by Moller et al. ¹⁹ , whose result was 34%, and is considered moderate. When compared to other studies, such as that by Frazao et al. ³ , 62.9% of the students had at least one permanent tooth affected by caries, with no statistically significant difference between the sexes.

Regarding the index used in other studies, the DMFT (decayed, missing or filled teeth) was analyzed by means of intraoral clinical examination ^20,19,7,12 . However, some studies used the Significant Caries Index (SIC ) to measure the severity of caries. The SiC index is intended to focus attention on individuals with the highest caries rates in each population. The index is calculated as follows: individuals are classified according to their DMFT values. The third of the population with the highest caries score was selected and the mean DMFT for this subgroup was calculated ^21,22,23 .

In the present study, the majority of schoolchildren (86.7%) had biofilm accumulation on the tooth surface. The verification method used in the study was only visual. Adequate oral hygiene is necessary to prevent oral pathologies that are common in schoolchildren ¹⁰. It is important to inform adolescents about the need to correctly remove dental biofilm by practicing adequate oral hygiene. Preschool children begin to learn about the concepts and principles that will be part of their education, so education on nutrition and oral health, like any other educational activity, should be introduced as early as possible by parents and teachers, preferably at an early age 25 ^. In

the present study, it was possible to verify the exaggerated consumption of sugary foods (cookies), and consumption of sugary drinks and/or soft drinks at least once a day. The result verified in another study reports that 60.8% of schoolchildren consumed stuffed cookies and 73.9% consumed sweetened juice, a fact that the authors attributed as contributing to a high prevalence of caries in adolescents ²⁶ . Culturally, individuals living in Brazil have the habit of consuming a lot of sugar, perhaps a remnant of the time of high sugar cane consumption. Furthermore, there is a veiled intake of fermentable carbohydrates available in typical foods from each region of the country ²⁵ .

Oral hygiene habits and access to dental services are important factors for preventing dental caries, as pointed out by Rigo et al. ⁷ in a study conducted in a city located in the northern region of Rio Grande do Sul. Regarding oral hygiene habits and toothbrushing frequency in the present study, most students (50.5%) reported brushing their teeth twice a day. A result similar to that obtained by Cypriano et al. ²⁷ , in which 50.9% reported brushing their teeth twice a day.

The present study has its design as a limitation, since it does not allow long-term monitoring of the selected students in order to observe the evolution of carious lesions or the treatment of untreated decayed teeth, as occurs with studies with a cross-sectional design ^5,16,23,18 . Therefore, it is suggested that a cohort study be carried out among adolescents in this municipality with a longitudinal design that allows cause-and-effect inferences with the determinants of dental caries. Even so, it can be stated that this research is of utmost importance for understanding the current oral conditions of schoolchildren in the municipality studied.

CONCLUSION

Based on the findings of this study, we conclude that the prevalence of untreated dental caries is high in schoolchildren from both schools analyzed, although according to WHO parameters, the average caries measured by the DMFT index is considered low in these schoolchildren, with no difference between the private and state schools in the municipality investigated.

There is a high daily consumption of sugary foods and beverages and the oral hygiene of schoolchildren was shown to be deficient when the presence of biofilm on the teeth was observed.