This study yielded two main findings. First, it highlighted that both sedentary behavior and unhealthy eating were associated with a higher prevalence and greater severity of impact on oral health-related quality of life among adolescents. Second, sensitivity analyses using e-values confirmed the relationships found between sedentary behavior and unhealthy eating with oral health-related quality of life. Controlling for social determinants, only a very strong unmeasured confounder would tend to alter the associations found.
The strengths of the study are related to its scope, as it was conducted in the five largest cities in the state, providing representative data of the population in question. Additionally, another important strength is particularly related to the strong presence of agriculture as the main economic activity. This specific economic characteristic may influence not only oral health patterns but also the dietary habits of the population.
A weakness of the study is its cross-sectional nature, which implies that we cannot establish causal inference in the results, limiting the ability to determine the direction of the relationship between variables.
The tested hypothesis was confirmed: adolescents with sedentary behavior (< 2 hrs/day watching TV, internet, playing video games, and other sedentary activities) and moderate to high unhealthy dietary consumption reported a greater impact on quality of life. Sedentary behaviour was associated with a higher CPO-D index in the evaluated adolescents when mediated by moderate to high unhealthy dietary consumption(5). The OIDP questionnaire assesses dimensions of oral health's impact on daily activities, and these activities were not elucidated in this analysis. However, a study conducted in Rio de Janeiro with adolescents in the same age group found that 88.7% of the students experienced an impact of oral problems on at least one of the daily performances evaluated by the OIDP. The activities that had the greatest impact were eating (81.3%), cleaning the mouth (40.5%), and smiling (32.2%), the average OIDP index was 7.1 with a 95% CI of 6.2 to 8.1(19). In Rio Grande do Norte, school adolescents aged 15–19 years, 51.16% reported some impact on oral health-related quality of life, with the main cause being the position of the teeth and activities such as eating, mouth hygiene, and smiling (20). Additionally, 40% of adolescents exhibited sedentary behavior (≥ 2 hrs/day, TV, internet, video games, and sitting activities), of whom 70% reported some impact on oral health-related quality of life. Adolescents from Cuiabá-MT, attended by the Family Health Strategy, had a prevalence of sedentary behavior of 55% (21).
The differentiation by gender of unhealthy dietary patterns and sedentary behaviour was not assessed in this study. However, when examining the association of physical activity levels and dietary habits with anthropometric and lipid profiles in adolescents, girls were found to have higher odds of having altered cholesterol and LDL-C levels (22). The Modified Canadian Aerobic Fitness Test (mCAFT) found that 31.5% of adolescents aged 15 to 17 in Florianópolis have low levels of aerobic fitness, with a higher prevalence in boys (49.2%) compared to girls (20.6%). Girls with sedentary behaviour, overweight, and high body fat percentage were the groups most likely to have inadequate aerobic fitness(23).
Parental education proved to be an important factor, exerting influence on dietary patterns and quality of life. 63.4% of adolescents with parents who had 1 to 4 years of formal education experienced some impact on oral health-related quality of life. Adolescents from public schools in João Pessoa-PB showed higher adherence to a dietary pattern classified as "snacks" (consumption of bread, butter and margarine, cheeses, processed meats, and coffee) when their mothers had lower levels of education and socioeconomic status (24). When analyzing children and adolescents with overweight and obesity, it is noted that the mother's education level of these adolescents ranges from ten to twelve years of schooling, with a percentage of 30.71% for overweight and 36.80% for obesity(25). Maternal education of less than four years presents a higher risk for short stature, with a decrease as maternal education increases (26). In Europe, a higher prevalence of overweight/obesity is associated with low family wealth. This led to the formulation of a strategy for implementing the promotion of healthy nutrition and physical activity for children and adolescents(2).
The relationship between sedentary behavior, unhealthy eating, and the development of dental caries is complex and multifactorial, highlighting the interconnection between lifestyle and oral health. Sedentary behaviours, such as spending long hours in front of the television or computer, often coincide with the consumption of snacks rich in sugars and fermentable carbohydrates, which are known to contribute to dental caries(27). Estudos indicate that diets high in simple sugars not only increase the risk of obesity and chronic diseases but are also one of the main dietary factors in the development of caries, as sugars serve as substrates for acidogenic bacteria in dental plaque, leading to demineralization of tooth enamel (28). Furthermore, a sedentary lifestyle may reduce the frequency of healthy oral hygiene habits, exacerbating the risk of caries. Therefore, promoting an active lifestyle along with a balanced diet low in free sugars is essential for preventing dental caries and maintaining oral and overall health(29).
Bomfim et al. (2021) highlight how sedentary lifestyles and diets rich in processed sugars and carbohydrates significantly contribute to the increased prevalence of dental caries. Additionally, the study, through structural equation models, showed that sedentary behaviour may be indirectly associated with less rigorous oral hygiene, and higher unhealthy dietary consumption, thus favouring the experience of caries among adolescents. This reinforces the need for integrated approaches promoting active lifestyles and balanced diets while minimizing sugar consumption as an essential strategy in preventing dental caries and promoting oral health(5).
According to data from the National School Health Survey of 2015, high prevalences of daily consumption of at least one group of ultra-processed foods and sedentary behaviour > 2 hours per day were identified. Out of every ten Brazilian adolescents, four exhibit regular consumption of ultra-processed foods, and seven have sedentary behaviour (30). Regarding cultural and behavioural explanations, the increasing use of social media and easy access to electronic devices justify sedentary behaviour. In a study conducted by Lucena et al. in 2013, analyzing the relationship between sedentary behaviour, dietary habits, indicators of quality of life, and health in adolescents, screen time was associated with lower levels of HRQoL for physical well-being and school environment, respectively (31).