The present study, nested in an epidemiological survey conducted with a representative sample of children from Quito, Ecuador, was designed to evaluate whether factors related to the school environment could influence the negative impact of TDIs on schoolchildren’s OHRQoL. We found that children from schools that experienced vandalism episodes in the last year exhibited a more negative impact on OHRQoL. Furthermore, this trend was also observed for children studying in schools that did not provide an adequate environment for tooth brushing of their students, and this variable remained significant even when the model was adjusted for TDI and other individual variables. Therefore, the positive characteristics of the school environment favoured a lower impact on OHRQoL, regardless of the occurrence of TDI and oral health disorders, supporting our working hypothesis.
A potential explanation for these findings is that children studying in schools with a more negative environment are probably from families with low socioeconomic status. Socioeconomic conditions can partially explain the higher prevalence of dental caries [13], although these factors were not usually associated with the occurrence of TDI [26]. On the other hand, socioeconomic conditions have been associated with the OHRQoL [17]. In the multiple model adjusted for the socioeconomic indicators and the occurrence of TDI and other oral health problems, the variable “vandalism episodes” did not achieve statistical significance. Thus, this fact can suggest the influence of individual socioeconomic characteristics on our findings.
These findings may be also explained by the lower prevalence of oral health disorders in these schools. For example, the occurrence of negative episodes such as bullying, vandalism, theft, and violence among students in schools was associated with a higher prevalence of dental caries [13] or TDI [12]. In our study, schools that experienced vandalism episodes exhibited a higher prevalence of TDI compared to schools where their coordinators did not report any occurrence of vandalism in the last year (14.8% and 0.8% for mild and severe TDI, respectively). Moreover, schools that have experienced episodes of vandalism against the patrimony presented the mean of CPQ11 − 14 scores approximately 20% higher than schools that have not experienced negative episodes. We also observed that children from schools with a favourable school environment in other aspects experienced less episodes of TDIs [21].
In addition to the decrease in prevalence of health problems, a positive school environment may favour a higher resilience among their students [27]. This effect can be observed with variables that were not directly associated with the prevention of TDIs. In our study, another contextual variable significantly associated with lower CPQ11 − 14 scores was the promotion of an appropriate tooth brushing environment at the schools. The mean of total CPQ11 − 14 scores in children attending these schools were approximately 20% lower than in children studying in other schools that did not provide time and an environment for tooth brushing. However, different to the occurrence of vandalism, this variable remained significant even in the adjusted model including oral health conditions and socioeconomic indicators. Thus, even though the prevalence of TDI in the schools that promote a safe tooth brushing environment was lower (11.0% and 0.8% for mild and severe TDI, respectively) than in schools without this routine (17.0% for minor TDI and 2.4% for severe TDI), multiple analyses suggest that the lower impact on OHRQoL is also associated with the promotion of these healthy habits.
Therefore, promotion of tooth brushing among the students, as well as other contextual variables related to health promotion measures (offering healthy meals and sports practices after regular class time), may be part of a general concept of health promotion for students. The concept of "Health Promoting Schools" comprises that broader health promotion measures are more effective than individual care [11, 28]. Previous studies have found a lower prevalence of oral health conditions in health-promoting schools [10, 11, 29, 30]. Moreover, positive effects related to health-promoting schools on OHRQoL have been observed [18]. Thus, in the present study, a possible explanation to the lower impact on OHRQoL in children from health-promoting schools, even in the adjusted model that incorporated the occurrence of TDI and other health conditions, may be the promotion of favourable healthy habits in these schools. These actions may favour healthier conditions [10, 11, 28–30], resilience [27], better quality of life [18], and other positive aspects [28].
However, these findings should be interpreted with caution. First, due to the nature of the study, it was not possible to collect where or how the TDIs occurred. Therefore, the direct relationship among the physical structure or occurrence of negative episodes in the schools and the occurrence of TDIs could not be evaluated. Nevertheless, authors have observed that many TDIs episodes in scholars occur in the school environment [4–6].
Other limitation is that other variables related to the promotion of healthy habits were not associated to lower CPQ11 − 14 scores. Furthermore, there were only four schools promoting a tooth brushing friendly environment, and the sample was restricted exclusively to public schools in the urban area of Quito. Thus, studies in other cities and countries, preferentially involving public and private schools, are necessary to corroborate our findings.
Despite the limitations, our study presents some strengths. This is the first study that evaluates the influence of contextual school environmental characteristics, as well as health promotion measures, on the impact of TDI on children’s OHRQoL. The occurrence of TDI, especially in the more severe stages, has been commonly associated with a negative impact on the OHRQoL of schoolchildren in primary studies [8, 9], as well as in a recent systematic review [7]. Despite of the low prevalence of children with severe TDI, this impact was confirmed in the present study, since children with severe TDI exhibited a greater impact on quality of life, even when adjusted for other variables.
In addition, this study demonstrated that even with the occurrence of TDI, schools that promote some health practices had a lower impact on OHRQoL. These findings favour the implementation of schools with supportive environments and that promote health measures. This effort could facilitate a reduction on the prevalence of oral health conditions and an improvement on OHRQoL. Besides, the implementation of health-promoting schools may favour other health conditions, as well as an improvement of the well-being and general quality of life of students, teachers, and staff of these schools [28]. However, the positive effect of these health-promoting schools on reducing health problems and improving health-related quality of life should be tested in cohort studies or cluster randomized clinical trials.
In conclusion, positive social environment and promotion of health practices in schools may reduce the impact of TDI on OHRQoL.