Effectiveness of school-based strategies to prevent tooth decay in Filipino children: A cluster-randomized trial.

1 INTRODUCTION

Filipino school children suffer from an alarmingly high burden of tooth decay that has been labelled as a “silent public health crisis.”^{1, 2} A national oral health survey revealed that 97% of 6-year-old children had dental caries with a mean of 8.4 affected teeth, and 85% had odontogenic infection.¹ High prevalence and severity of untreated tooth decay are common observations around the globe, particularly for children in low- and middle-income countries and deprived populations.³ Unfortunately, the significant negative consequences of tooth decay on health, growth and quality of life of children often go unnoticed and simple preventive interventions are not prioritized.^4–8

Even though schools have long served as a platform for public health interventions, there is no generally agreed model for oral health promotion and limited evidence is available for realistic approaches in low- and middle-income settings.⁹ Due to the limited resource availability, the shortage of the oral health workforce and the overwhelming burden of disease, it is important to strengthen evidence for preventative interventions that are cost-effective and that can be applied within the existing education sector structures. Interventions requiring special training, costly supplies and equipment, or referral to a dental clinic are not realistic and will have limited population-wide impact over time since they can only reach a limited number of children. Instead, the World Health Organization (WHO) and FDI World Dental Federation recommend that oral health promotion efforts focus on increasing the availability and use of fluorides and providing oral care that matches community needs and available resources.^10–13 The caries-preventive benefits of fluorides have been well-established in the literature¹⁴ and can be delivered through various forms, including fluoridation of water, salt or milk, the use of fluoride toothpaste or through application of gels or varnishes. In addition to prevention, access to basic emergency oral care and pain relief is required to address acute consequences of oral disease in populations.

The Philippine Department of Education (DepEd), with technical support from the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), created the Essential Health Care Programme (EHCP) to address priority diseases of primary school students in the Philippines, including tooth decay. Building on the Fit for School approach, EHCP integrates water, sanitation and hygiene interventions in primary schools, including the construction of handwashing facilities, the practice of daily group handwashing and toothbrushing and biannual deworming.^{15, 16}

The Fit for School Health Outcome Study (FITHOS) was undertaken by the Regional Office of the Department of Education, Health and Nutrition Unit, in Cagayan de Oro, Misamis Oriental, with technical and financial support by GIZ and international academic institutions. FITHOS is a longitudinal cohort study designed to strengthen evidence of the health impact of EHCP. The study protocol included an assessment of different approaches to addressing the burden of tooth decay in children, including daily group toothbrushing with fluoride toothpaste and additional access to on-demand oral urgent treatment (OUT) or weekly application of high-concentrated fluoride gel. Results of the FITHOS presented here were not part of the previous publication of the full methodology and 1-year results.¹⁷

The hypotheses were that children receiving daily group toothbrushing with fluoride toothpaste as part of EHCP, and those receiving additional OUT or weekly application of fluoride gel, would have lower incidence of dental caries and odontogenic infections compared to children receiving standard oral health education. Compared to children receiving daily group toothbrushing with fluoride toothpaste only, it was hypothesized that children receiving additional OUT and those receiving additional weekly application of fluoride gel, would have lower incidence of odontogenic infections and a lower incidence of dental caries and odontogenic infections, respectively.

2 METHODS

2.1 Study design and sample

The Fit for School Health Outcome Study was a cluster-randomized trial conducted in the Philippines from 2009 to 2012 (Figure 1). The study was reviewed and approved by the Institutional Review Board of the Kinaadman Research Center (Xavier University, Cagayan de Oro, Philippines) and is registered with the German Clinical Trial Register DRKS (DRKS00003431) and the WHO (WHO Universal Trial Number U1111-1126-0718). Written consent was obtained from parents or caregivers for all children participating in the study. This study is reported in compliance with the Consolidated Standards of Reporting Trials (CONSORT) guidelines. The general methodology, sampling procedure, sample size calculation and other study details are described in a previous publication.¹⁷

The study was conducted on the island province of Camiguin because of its comparably low migration rate and stable socioeconomic indicators. Drinking water in the Philippines, including Camiguin, is not fluoridated; data from the National Oral Health Survey revealed that 99.2% of water samples present concentrations between 0.04 and 0.6 ppm, which is below the optimal fluoride concentration of 0.7 ppm in a subtropical climate.¹ The study consisted of three experimental groups and an external concurrent control group. Three regions in Camiguin (with a total of 56 schools on the Island) were randomly assigned to the three experimental groups with simple randomization using three shuffled folded notes. No allocation of concealment method was used. From each region, a random selection of schools was drawn until at least 200 first-grade students could be included. Due to the local government’s decision to implement EHCP in the entire province of Camiguin, a concurrent external control group without the EHCP programme was selected from Gingoog City (Northern Mindanao) on the nearby mainland, which had a similar child population in terms of socioeconomic characteristics. Inclusion criteria for the selection of public elementary schools for both experimental and control groups were as follows: school’s location either along a highway or no more than one kilometre from a highway; no problems related to law and order in the surrounding community. In each school, baseline data were collected from a random sample of first-grade students aged 6–7 years in 2009, and data were collected in August-September of each following year until 2012.

The four study groups had the following characteristics:

1. Intervention group one (four schools, n = 160 children) received the EHCP programme, consisting of daily supervised group handwashing with soap, daily supervised group toothbrushing with fluoride toothpaste (0.3 ml per usage, containing 1450 ppm fluoride), as well as biannual deworming with a single dose of albendazole.
2. Intervention group two (eight schools, n = 169 children) consisted of EHCP with additional access to OUT (EHCP + OUT) as defined by the WHO, in which emergency oral care was offered twice a year at each participating school for children suffering from toothaches due to advanced dental caries. These on-demand services included extractions, draining of abscesses and drug administration where required.
3. Intervention group three (six schools, n = 192 children) received EHCP with the addition of a high-concentrated fluoride gel once a week instead of the usual toothpaste regimen (EHCP + Fluoride). Fluoride gel (Elmex GelW, Gaba GmbH Lörrach, Germany; 0.3 ml per usage containing 12 500 ppm fluoride) was applied on the toothbrush, and children were instructed to brush for 2 min, after their normal group toothbrushing routine.
4. The external control group (three schools, n = 161 children) received a standard health education programme as defined by the Philippine DepEd, including a single commercial toothpaste sachet, a toothbrush and an instructional oral health message at the beginning of the school year. The standard health education programme is implemented on a national level in all public elementary schools in the Philippines, including the schools from the three experimental groups.

3 RESULTS

The study sample included a total of 682 children who completed all four examinations (follow-up rate from 2009 to 2012: 80.0%). The main reason for loss to follow-up was school drop-out (approximately 5%–7% per year) and families moving from the area to another village for income generation. Summary descriptive statistics are shown in Table 1. There were 328 males (48.1%), and the average age at baseline was 7 years across all experimental groups.

At baseline, the mean number of decayed primary teeth, DMFT, DMFS and PUFA at baseline was 5.1 ± 3.3, 0.7 ± 1.0, 0.9 ± 1.7 and 0.1 ± 0.3, respectively. The caries prevalence at baseline was 96.8%, the care index was 0.2%. Figure 2 shows the mean d, DMFT, DMFS and PUFA at the four study points (2009, 2010, 2011 and 2012) per treatment group. Table 2 presents the incidence densities for study outcomes, showing the rate at which new events occur throughout the full study duration. A series of negative binomial regression models comparing treatment groups for each outcome at baseline indicated that there were significant differences in baseline oral health status for all four outcomes. Particularly children in the control group had higher d, DMFT, DMFS and PUFA at baseline than children in the experimental groups.

Longitudinal model results (Table 3) show that children receiving plain EHCP had lower increment of DMFT by 22% (IRR = 0.78, 95% CI = 0.60, 1.01) than the control group, but this was not significant at the 5% level. Increments of d, DMFS and PUFA did not statistically differ between the EHCP group and the control group. Compared to controls, children receiving EHCP + Fluoride had significantly lower increments of DMFT, DMFS and PUFA by 40% (IRR = 0.60, 95% CI = 0.47, 0.77), 40% (IRR = 0.60, 95% CI = 0.44, 0.83) and 47% (IRR = 0.53, 95% CI = 0.29, 0.90), respectively, after adjusting for confounders. Children receiving OUT in addition to EHCP also had lower incidence rates of incremental DMFT and DMFS by 23% (IRR = 0.77, 95% CI = 0.59, 0.99) and 28% (IRR = 0.72, 95% CI = 0.52, 0.99), respectively, than controls. Lower incidence rates were also found for PUFA by 46% (IRR = 0.54, 95% CI = 0.29, 1.03), but effects were not statistically significant. No significant differences in d were found for plain EHCP, EHCP + Fluoride, EHCP + OUT compared to standard care. As expected, the incidence rates of d, DMFT, DMFS and PUFA all increased with age. The participants’ sex, the number of siblings and whether they lived in a household with a television were not significantly associated with d, DMFT, DMFS or PUFA.

Mainly positive preventive fractions PFs were found in all three experimental groups, indicating that the crude 3-year increment in DMFT, DMFS and PUFA was lower in the experimental groups than the control group (Table 4). For the EHCP + Fluoride intervention compared to care as usual, the preventive effect was substantial for DMFT and PUFA and moderate for DMFS. For the EHCP + OUT intervention, a substantial preventive effect was found for PUFA.

4 DISCUSSION

This study investigated school-based strategies to prevent dental caries in a high-risk child population in the Philippines. The interventions studied, namely toothbrushing with fluoride toothpaste, weekly application of fluoride gel and on-demand oral urgent care, are all supported by strong evidence from controlled clinical studies.^{14, 24, 25} Still, public health research is crucial to evaluate the effectiveness of such interventions when implemented at population or community levels under real-life circumstances, particularly in low- and middle-income settings where the disease burden is high, resources are scarce and workforce capacity is limited. In the current study, interventions were implemented in an unsupported government-run school programme, which provided such a real-life setting. The findings of this research help to understand which interventions can be applied and translated into realistic oral health promotion strategies in high-risk populations and contributes to the evidence base for informed policy decisions.

This study showed clear caries-inhibiting benefits of a weekly use of a high-concentrated fluoride gel in addition to daily school-based toothbrushing, significantly reducing the incidence of decayed permanent teeth, decayed permanent surfaces and pulpally involved permanent teeth after 3 years by 40%, 40% and 47%, respectively. A Cochrane review confirmed the clinical effectiveness of fluoride gels, including the absence of adverse health effects from accidentally swallowing the gel.²⁵ High-concentrated fluoride gel does not require professional intervention, but can safely be applied by children from 6 years onwards under supervision of a school teacher at low costs. These findings highlight that the use of fluoride gels in schools offers a realistic and potentially cost-effective approach to promote child oral health, which can be implemented at meaningful scale.

Findings also suggest that the additional provision of on-demand emergency oral treatment for children suffering from toothache due to advanced dental caries may contribute to a reduction in the number of permanent teeth with dental caries or odontogenic infections. In the Philippines, around 80% of children suffer from dental infection.¹ The toothache that follows on is often severe, resulting in lost time from school, poor school performance and decreased quality of life.^26–28 Since children often have limited access to oral health care, priority should be given to ensuring basic, essential services for the most urgent oral health needs of schoolchildren. Such services, involving mainly dental extractions, can be delivered by a trained dental nurse,²⁹ thereby providing a realistic solution for low-resource settings.

Children receiving school-based toothbrushing only had a 22% lower rate of DMFT in children receiving EHCP compared to standard care, which was significant at the 10% level, but not at the 5% level. No impact was found on DMFS and PUFA. Other studies across various countries reported positive impacts of school-based daily toothbrushing with fluoride toothpaste on children’s caries experience.^30–33 A cohort study similar to the FITHOS was conducted to evaluate the health impacts of the EHCP programme (implemented as the “Fit for School” programme) in elementary schools in Cambodia, Indonesia and Lao PDR.¹⁶ Findings showed a 24% reduction in the number of decayed permanent teeth (PF ranging from 18% to 38% among the three participating countries), which confirms the findings of a Cochrane meta-analysis of the caries-preventive benefits of fluoride toothpaste.³⁴ Conversely, evidence for the effectiveness of educational approaches to produce sustained oral health improvements is very weak, particularly when solely focused on knowledge provision and toothbrushing instructions.³⁵

There are several factors that may explain why this study found only small reductions in dental caries in the permanent teeth by school-based toothbrushing alone. First, the quality of programme implementation may have played an important role; notably, implementation was supervised by school teachers, not by dedicated project team members. Poor compliance to the protocol limits the ability of potentially effective interventions to reach their full potential. Although data on implementation quality were not available in this study, challenges with intervention compliance are common barriers to effective school-based hygiene interventions.³⁶ First-year findings of the FITHOS were promising, showing lower caries incidence in the EHCP group compared to the control group, although this finding was not statistically significant.¹⁷ It is probable that engagement after the first year and intervention compliance deteriorated, as no monitoring system was in place to control for adherence to the protocol. Hence, institutional compliance with intervention protocols may be a crucial confounding factor that should be considered in future programme implementation, long-term management and evaluation research.

Second, it is plausible that this study may not have been able to demonstrate substantial impact due to some methodological limitations. Although the experimental arms were randomly assigned, randomization of the control group was not possible based on the local government decision to implement EHCP in the entire province of Camiguin. Despite efforts to select an external concurrent control group from another province based on similar socioeconomic and health characteristics, there were significant baseline differences in caries status between children in the control arm versus the experimental arms. These baseline differences did not allow true comparison of the interventions’ effect relative to the control group. Furthermore, these differences suggest that there may have been important confounding factors, such as socioeconomic status, hygiene and dietary factors, that were unequally distributed among the experimental and control groups. Attempts were made to minimize these effects by analysing caries outcomes as the increment between baseline and study completion and by adjusting for potential confounders, such as television ownership, age and sex. Bias from potentially selective drop-out was probably minimal, since the 3-year follow-up rate was high. However, no intention-to-treat analyses were performed, and therefore, selection bias cannot be completely discarded.

School-based toothbrushing remains one of the few realistic public health strategies in low- and middle-income settings known to deliver positive oral health benefits. The results of this study, demonstrating reductions in dental caries but not significant, reinforce calls for regular monitoring of implementation quality, commitment and capacity of school staff and governance under the education sector’s leadership for school-based toothbrushing to be effectively implemented. Notably, the Philippine Department of Education has recently required including supervision of daily hygiene activities at school (e.g., handwashing and toothbrushing) in teacher’s job descriptions; complemented by developing a water, sanitation and hygiene (WASH) policy; implementing guidelines for teacher training; and ensuring budget allocations are made for hygiene supplies (e.g., soap and fluoride toothpaste). A monitoring system was also put in place to institutionalize responsibility of hygiene activities within public schools nationwide.

In conclusion, this study showed clear caries-inhibiting effects of the weekly application of high-concentrated fluoride gel, in addition to daily school-based toothbrushing with fluoride toothpaste, providing evidence that this is a potentially viable strategy to reduce the incidence of tooth decay and odontogenic infection in permanent teeth of Filipino children. Furthermore, the provision of on-demand urgent oral treatment shows to be a realistic and essential service in schools to lower the burden of dental caries in children. This study did not demonstrate significant caries-preventive benefits of school-based toothbrushing only versus standard health education, which may be due to implementation challenges. Findings of this study have been instrumental to advocate with decision makers to re-direct the limited resources for oral health care towards locally determined effective interventions that are focused on increasing the use of fluorides and providing urgent oral care for the most frequent needs of children, using the school as a health-promoting setting. This is an essential approach to address the “silent public health crisis” of dental caries in low- and middle-income settings.

CONFLICT OF INTEREST

The authors declare that they have no conflict of interest.

AUTHOR CONTRIBUTIONS

BM, EN and HB conceptualized the study. BM and EN were the principal investigators. BM, EN, GSI and SM supported the data collection in the field. RRR and DD performed the statistical data analysis and contributed to writing the paper. RRR, BM, DD, GSI, SM, EN and HB contributed to the critical interpretation of the data. DD drafted the first version of the paper and was involved in conceptualizing the study and data interpretation. All authors gave their final approval and agree to be accountable for all aspects of the work.