The effectiveness of school-based supervised tooth brushing intervention for preventing dental caries: a systematic review and meta-analysis

Abstract

Background

Dental caries ranks among the most frequent childhood diseases worldwide, significantly impacting oral health and overall well-being. The objective of this systematic review and meta-analysis was to evaluate the efficacy of school-based supervised toothbrushing (STB) intervention in the prevention of dental caries by enhancing oral hygiene.

Methods

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) sourced from PubMed, Scopus, Web of Science, and other databases up to February 2025. Eligible studies were those that contrasted school-based STB intervention with no-intervention controls, documenting results in DMFT/dmft or DMFS/dmfs indices. Two reviewers independently screened studies, extracted data, and assessed risk of bias using Risk of Bias 2 (RoB2) tool. A random-effects model was used to pool the results, and standardized mean differences (SMDs) were calculated to account for differences in dentition types. Heterogeneity was assessed using the I² statistic and Cochran’s Q test.

Results

Five of the eight RCTs that satisfied the inclusion requirements were included in the meta-analysis. A statistically significant reduction was shown in DMFS/dmfs that resulted from STB intervention (SMD = -0.22; 95% CI: -0.42 to -0.01; p = 0.037; I² = 64.6%), indicating a modest preventive effect with moderate heterogeneity. However, there was no significant effect on DMFT/dmft (SMD = 0.05; 95% CI: -0.27 to 0.37; p = 0.754; I² = 86.8%), reflecting high between-study variability.

Conclusion

School-based supervised toothbrushing intervention appear to effectively reduce dental caries at tooth surface level, as reflected in the significant reduction in DMFS/dmfs scores. However, their effect on whole-tooth caries, as measured by DMFT/dmft, remains less evident in the short term. These findings support using STB as a practical community-level intervention to promote oral health in children.

Trial registration

We have registered the protocol on the Open Science Framework (OSF) (Registration DOI: 10.17605/OSF.IO/2JWR9).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-025-07299-y.

Introduction

Dental caries are a frequent but avoidable chronic illness [1, 2]. The World Health Organization (WHO) utilizes the decayed, missing, and filled teeth (DMFT) index to measure worldwide oral health status. According to the World Health Organization, the average DMFT score for 12-year-old children is 4.1 in underdeveloped countries and 3.3 in industrialized nations [1].

The accumulation of dental plaque results in increased acid production in the oral cavity, resulting in demineralization and, ultimately, tooth decay [2]. In children, untreated dental caries can lead to pain, infection, difficulty eating, and impaired learning, significantly reducing the quality of life for both the child and their family.

Dental caries is a multifactorial disease, but it can be effectively controlled if detected early [2]. Regular toothbrushing with fluoridated toothpaste is an effective prevention method, as it removes plaque and reduces the risk of caries [3]. However, for optimal benefits, children should brush their teeth under the supervision of an adult (e.g., a hygienist, teacher, or dentist), ensuring proper brushing technique, timing, and the appropriate use of toothpaste [3].

Supervised tooth brushing (STB) in the schools provides an ideal setting for reinforcing this healthy habit, creating an encouraging environment for children’s oral health promotion. Previous research, including the toolkit from the office for Health Improvement and Disparities (OHID), showed STB as a cost-effective approach to caries prevention [4].

However, evidence on the effectiveness of these interventions remains mixed. For example, a 2017 systematic review by Dos Santos et al. included four studies but found inconsistent and sometimes contradictory results in terms of methodological differences among the included trials [5].

This systematic review intends to update the existing evidence by comprehensively identifying and synthesizing findings from recent studies on school-based STB intervention, providing a more definitive assessment via the meta-analysis.

Materials and methods

Protocol Registration and Eligibility criteria

This systematic review only included randomized controlled trials (RCTs) published in English that assessed the efficacy of STB intervention using DMFT/S or dmft/s as outcome measures. We have registered the protocol on the Open Science Framework (OSF) to enhance transparency and reproducibility (Registration DOI: 10.17605/OSF.IO/2JWR9). To focus on the efficacy of STB as a community-based intervention, only studies conducted in the schools or kindergartens were included. Furthermore, eligible studies required STB to be the sole intervention for the experimental group, with no intervention provided to the control group. Studies having a follow-up period of less than one year were omitted to guarantee sufficient monitoring of the intervention impact, since dental caries need time for development. No temporal limitations were imposed on the search to enhance comprehensiveness.

Information sources and search strategy

PubMed, Cochrane Library, Science Direct, Web of Science, Scopus, Google Scholar, and clinical trial registers were all searched electronically; the most recent search was carried out in February 2025. The search strategy combined keywords such as “supervise,” “caries,” “toothbrush,” “school,” and “kindergarten” using Boolean operators (AND, OR). Besides, the reference lists of related reviews and included studies were manually screened to identify potentially relevant articles not captured in the electronic searches.

Selection and data collection process

Studies identified via the literature search were imported into EndNote 20. Duplicate records were first automatically removed, followed by a manual check by the first author (Sh.T) to ensure complete removal. Thereafter, the titles and abstracts of the remaining papers were evaluated for pertinence. Articles that failed to meet the inclusion criteria were excluded at this stage. Two authors (Sh.T and NS) then performed separate full-text reviews to verify eligibility. Only studies evaluating STB as the sole intervention in school or kindergarten settings, using DMFT/dmft or DMFS/dmfs as outcome measures, were included. To assess caries experience in the primary dentition, the dmfs index was used throughout the review. Although only Al-Jundi et al. used the term defs, both indices refer to the same components (decayed, extracted/missing, and filled) which are considered equivalent [1, 6]. For consistency across studies, the term dmfs was applied uniformly in data extraction and analysis.

The inclusion criteria were strictly enforced, and any discrepancies were resolved through collaborative discussions among all team members. A third auditor (AT) was enlisted in instances where agreement could not be reached. The PRISMA flow diagram (Fig. 1) provides a comprehensive overview of the study selection procedure [7].

Fig. 1.

PRISMA flow diagram of study selection

Data items and data extraction

A standardized data extraction form was created in Microsoft Excel to systematically collect all pertinent research data. This form encompassed essential elements including participant characteristics (e.g., age and sex), publication details (e.g., year and country), study design attributes (e.g., control and test group sizes), intervention specifics (e.g., type of supervisor, brushing frequency, and fluoride concentration of toothpaste), as well as follow-up duration and outcome measures. The form was designed based on predefined eligibility criteria to ensure consistency and completeness in data collection.

Risk of bias assessment

The updated RoB 2 instrument was employed by two reviewers (Sh.T and NS) to independently evaluate the risk of bias, as recommended by the Cochrane Collaboration [8, 9]. In order to guarantee consensus, discrepancies in assessments were resolved through dialogue with a third assessor (AT). Table 2 offers a comparative summary of the evaluations. RoB 2 tool specifically evaluated randomized trials across five critical domains, including the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result.

Table 2.

RoB2 (risk of bias) assessment

Author/Year	Domain 1: Randomization process	Domain 2: Deviation from the intended interventions	Domain 3: Missing outcome data	Domain 4: Measurement of the outcome data	Domain 5: Selection of the reported results	RoB-2 final quality assessment
1. Curnow et al. [15]	Some concern	Low risk	Low risk	Low risk	Low risk	Some concern
2. Rong et al. [11]	Some concern	Low risk	Low risk	Low risk	Low risk	Some concern
3. Winter et al.[16]	Some concern	Low risk	Some concern	Low risk	High risk	High risk
4. Al jundi et al. [1]	Some concern	Some concern	Low risk	Some concern	Some concern	High risk
5. Frazao [14]	unclear	High risk	unclear	Low risk	High risk	High risk
6. Jackson et al. [10]	Some concern	Low risk	Low risk	Low risk	Low risk	Some concern
7. Helderman et al. [13]	Some concern	Low risk	Low risk	Low risk	Low risk	Some concern
8. Schwarz et al. [12]	High risk	Some concern	Low risk	Some concern	Some concern	High risk

Statistical analysis

In order to ascertain the eligibility of studies for inclusion in the meta-analysis, data regarding the DMF/dmf index (including means and standard deviations at baseline and/or follow-up, or between-group differences) were extracted from each included study. Only five of the eight studies (Heldermanet al. 1997, Schwarz et al. 1998, Rong et al. 2003, Jackson et al. 2005, Al-Jundi et al. 2006) included in the systematic review provided adequate quantitative data for inclusion in the meta-analysis [1, 10–13]. The other three studies (Curnow, Pine et al. 2002, Frazão 2011, Winter et al. 2017) were not included in the meta-analysis as they failed to provide baseline or follow-up dmft index data (for example, missing means or standard deviations) [14–16]. To evaluate the impact of the STB on the DMFT/dmft and DMFS/dmfs indices independently, a meta-analysis was carried out using the Metan module in STATA 17 [17]. For studies reporting mean changes from baseline and their standard deviations (SDs), these values were directly used. For studies without reported changes, they were calculated from baseline and post-intervention data. All calculations and conversions, including deriving SDs from 95% confidence intervals (CIs) or standard errors (SEs), were performed using the Meta-Analysis Accelerator tool [18]. Post-intervention sample sizes were used in terms of variations between baseline and follow-up. Given the inclusion of both primary and permanent dentition data within each index (DMFT/dmft and DMFS/dmfs), and the variability in scale, the standardized mean difference (SMD) was selected as the summary effect size to enable comparability. SMD was calculated using Hedges’ g, which adjusts for small-sample bias. A random-effects model was applied to account for clinical and methodological heterogeneity, including differences in dentition type, age groups, and study settings. Heterogeneity was evaluated using the I² statistic and Cochran’s Q test. Assessment of publication bias was not performed due to the small number of included studies (n < 10), in line with Cochrane recommendations. Statistical significance was set at p < 0.05.

Results

Study selection and eligibility

A total of 2,249 records were identified through the systematic search. After removing 437 duplicate records a total of 1,812 records were kept for title and abstract screening. Of these, 1,763 records were removed based on title and abstract screening, with 49 articles kept for full-text retrieval. Of the 49 articles, 35 were successfully retrieved and assessed for eligibility. Of the 35 articles reviewed in full, 10 studies (Conchie et al. 1969, Bagramian et al. 1976, Vestergaard et al. 1978, Kallar et al. 2011, Stokes et al. 2011, Agouropoulos et al. 2014, Petersen et al. 2015, Pieper et al. 2016, Goldman et al. 2017, Zeeberg et al. 2018) were excluded because the intervention provided to the test group included additional elements beyond STB [19–28]. Nine studies (Hope 1979, Suomi et al. 1980, Haugejorden and Rise 1981, Marthaler 1981, Pine et al. 2007, Macpherson et al. 2013, Tarvonen et al. 2016, Cakar et al. 2018, Abuhaloob and Petersen 2023) were excluded as they did not use a RCT design [29–37]. Four studies (Graesser et al. 2017, Maya et al. 2018, Babaei et al. 2020, Chuang et al. 2022) were excluded because they did not use DMF indices (DMFT, DMFS, dmft, dmfs) to assess the dental caries [38–41]. In the other two excluded studies (Spears et al. 1978, Hilgert et al. 2015), adults brushed the children’s teeth after the STB intervention, which interfered with the study design and led to their exclusion [42, 43]. Two further studies (Leous et al. 2009, Damleet al. 2014) were omitted owing to limited follow-up periods [44, 45]. Finally, 8 RCTs satisfied the inclusion criteria for the systematic review ( Helderman et al. 1997, Schwarz et al. 1998, Curnow et al. 2002, Rong et al. 2003, Jackson et al. 2005, Al-Jundi et al. 2006, Frazão 2011, Winter et al. 2017) [1, 10–16], with 5 of them (Helderman et al. 1997, Schwarz et al. 1998, Rong et al. 2003, Jackson et al. 2005, Al-Jundi et al. 2006) included in the meta-analysis [1, 10–13]. Figure 1 shows the complete selection process, including identification, screening, and reasons for exclusions.

Study characteristics

Studies included in this review were conducted across seven countries, with STB intervention implemented in schools or kindergartens under the supervision of trained individuals, such as teachers or trained parents. However, studies differ in terms of toothpaste fluoride concentration, age groups, caries risk of the targeted population and study durations.

Participants varied in age from 3 to 14 years old, with fluoride concentrations in toothpaste ranging from 0 to 1450 ppm. All clinical evaluations were carried out under natural lighting (Table 1).

Table 1.

Characteristics of included RCTs

Author country (Year)		Sample characteristics												Index evaluated	Mean(SD) (intervention/control) (data used in meta-analysis)
		Size	Lost to follow-up		Age	Supervisor	Frequency of intervention	Toothpaste fluoride concentration			brushing technique	Follow-up duration
		(test/control)
1. Curnow et al. Scotland [15]		279/255		40/33	5 years	Local trained mothers	school-days	1000 ppm*		not mentioned			2 years	dmfs*, DFS*	-
2. Rong et al.China [11]		361/370		103/114	3 years	Teachers	Twice a day, school-days	1100 ppm		not mentioned			2 years	dmfs	2.47(4.09)/ 3.56(5.3)
3. Winter et al. Germany [16]		125/381		Not mentioned	Primary school	Trained dental assistants	School-days	1400 ppm		not mentioned			3 years	dmf, DMF*	-
4. Al Jundi et al. Jordan [1]		6 years old: 218/212 11years old: 218/208		6 years old: 11/9 11years old: 14/14	6 and 11 years	Research assistant	School-days	500 ppm for 6 years old 1000 ppm for 11 years old		horizontal scrub			4 years	DMFT*, dmft*	6 Years-old: 0.02(3.2)/ 0.26(3.25) 11 Years-old: 0.1(1.9)/ 0.3(1.95)
5. Frazao Brazil [14]		344/283		53/37	5 years	Dental assistant	School-days	1100 ppm		cross-brushing			18 month	dmft	-
6. Jackson et al. Uk [10]		259/258		78/69	5–6 years	Teachers	School-day	1450 ppm/		toothbrushing technique appropriate for young children			2 years	dmfs, DMFS*	2.58(12.24)/ 2.93(11.97)
7. Helderman et al. Tanzania [13]		400/150		91/28	9 to 14 years	Teachers	weekly	No fluoride		horizontal short stroke and marginal gingiva			3 years	DMFT	0.5(0.26)/ 0.4(0.26)
8. Schwarz et al. China [12]		168/121		16/22	3–4 years	Teachers	School-days	1000 ppm		simple mini-scrub			3 years	dmfs	3.6(5.55)/ 6.3(7.56)

*dmft decayed, missing, and filled teeth – primary teeth, dmfs decayed, missing, and filled surfaces – primary teeth, DMF decayed, missing, and filled – permanent teeth, DMFT decayed, missing, and filled teeth – permanent teeth, DMFS decayed, missing, and filled surfaces – permanent teeth, DFS decayed and filled surfaces, PPM parts per million – fluoride concentration

Risk of bias assessment

The RoB2 evaluation showed that none of the included studies had a “low risk of bias.” Overall, four studies were deemed to have “high risk” and four to have “some concerns”. Due to a lack of thorough explanations of the randomization procedure, five studies exhibited an unknown risk of randomization bias [1, 10, 13–15]. Regarding the lack of information about randomization, one of the studies had a significant risk of bias in randomization [16].

Performance bias was unclear in six studies, as no information was provided regarding the awareness of teachers and parents about the intervention [10, 11, 13–16]. In two studies classified as having a high risk of performance bias, it was explicitly mentioned that parents or supervisors were not blinded to the intervention [1, 12].

Despite the fact that all studies reported some participant loss to follow-up, predominantly due to minors exiting school, none were deemed to have a high risk of attrition bias. Nevertheless, one study was classified as high risk for attrition bias due to the absence of unambiguous data on group sizes [16]. The aggregate risk of bias assessments for the included studies are summarized in Table 2.

Meta-analysis

A total of five randomized controlled trials were included in the meta-analysis. Among these, three studies reported data on DMFS/dmfs, and two studies reported data on DMFT/dmft. One study (Al Jundi et al.) contributed two age-specific subgroups (6 and 11 years) to the DMFT/dmft analysis, resulting in six independent data entries across the two indices [1].

DMFS/dmfs meta-analysis

Three studies, including 591 individuals in the intervention group and 544 in the control group, were examined. The intervention resulted in a statistically significant reduction in DMFS, with a pooled standardized mean difference (SMD) of −0.22 (95% CI: −0.42 to −0.01, p = 0.037) compared to the control group, demonstrating that the intervention had a positive impact on lowering the number of decayed, missing, and filled surfaces (Fig. 2).

Fig. 2.

Forest plot of standardized mean difference (SMD) in DMFS/dmfs between intervention and control groups

Heterogeneity was moderate (I² = 64.6%, Q chi-square = 5.65, df = 2, p = 0.059), suggesting notable variability between studies. The estimated between-study variance was τ² = 0.021.

DMFT/dmft meta-analysis

Three records were evaluated, comprising 720 participants in the intervention group and 519 participants in the control group, which were derived from two studies. The pooled SMD was 0.05 (95% CI: −0.27 to 0.37, p = 0.754), indicating no statistically significant effect of the intervention on DMFT/dmft scores (Fig. 3).

Fig. 3.

Forest plot of standardized mean difference (SMD) in DMFT/dmft between intervention and control groups

However, heterogeneity was high (I² = 86.8%, Q chi-square = 15.12, df = 2, p = 0.001), reflecting substantial differences among studies, with an estimated between-study variance of τ² = 0.069.

Discussion

The presence of an adult can encourage children to brush their teeth more effectively, potentially reducing the risk of tooth decay [3, 38, 46]. Moreover, STB may offer educational benefits by gradually teaching children proper brushing techniques, which can lead to the development of more consistent oral health habits over time [38, 46]. Since dental caries may be avoided by developing good brushing habits early in life, the purpose of this systematic review was to assess how group-based STB intervention affected the DMFT/dmft and DMFS/dmfs indices.

Eight studies that satisfied the predetermined inclusion and exclusion criteria were identified through a thorough search of numerous databases. The control groups received no intervention for comparison, while all included studies were randomized controlled trials that evaluated STB as the intervention. Five of these studies satisfied the criteria for meta-analysis. A statistically significant decrease in DMFS/dmfs values was observed in the STB group in three of these studies in comparison to the control groups, as indicated by the results.

Al-Jundi et al., Jackson et al., Schwarz et al., and Rong et al. reported statistically significant differences in the primary dentition [1, 10–12], Conversely, Winter’s study did not identify a significant association [16]. Significant differences were identified in the permanent dentition by Al-Jundi et al. and Curnow et al. studies [1, 15], while Jackson et al., Helderman et al., and winter et al. reported no significant effects [10, 13, 16].

The meta-analysis demonstrated a statistically significant decrease in DMFS/dmfs scores in the intervention group relative to the control group, suggesting that STB effectively reduces the incidence of decayed, missing, or filled surfaces. The pooled analysis of DMFT/dmft scores did not reveal a statistically significant difference, indicating a more restricted effect on the count of decaying, missing, or filled teeth. This gap may be partially attributable to the intrinsic difference among these indices. The DMFT/dmft index assigns a single point per affected tooth, regardless of the number of surfaces involved, whereas DMFS/dmfs index captures the exact number of affected surfaces. As a result, DMFS/dmfs measure not only provides a more detailed assessment but also has greater statistical power to detect small but meaningful differences in surface-level prevention. This can lead to more pronounced reductions in DMFS/dmfs scores, while similar gains may have a less noticeable effect on the DMFT/dmft score. This difference emphasizes the relevance of include both indices when assessing the efficacy of preventative programs since they cover different elements of oral health. Future research should investigate integrating both measures to offer a more complete picture of intervention effects.

Four randomized controlled trials (RCTs) were included in a comparable systematic review by Dos Santos et al. in 2017, but no meta-analysis was carried out, most likely because there were not enough relevant papers at the time [5]. On the other hand, a meta-analysis was able to statistically evaluate the impact of STB on DMF outcomes since the current evaluation had a greater number of trials.

The significant variability seen, however, suggests that there was a great deal of variation in the study environments, participant ages, fluoride levels, follow-up times, and brushing techniques, all of which would have affected the pooled findings. A random-effects model was applied to account for overall heterogeneity across studies; however, due to the limited number of included studies, it was not feasible to explore these sources of heterogeneity using subgroup analyses or meta-regression, which restricts the conclusiveness of this evaluation. In order to more accurately quantify the long-term effects of STB on dental caries, additional high-quality RCTs with consistent procedures and longer follow-up periods are necessary.

Moreover, the studies included in this review had several limitations, especially concerning their risk of bias. When analysing the results, care must be used since these problems might compromise the findings’ dependability. The variation in the reported brushing methods is another drawback of the included research. Although the methods, such as horizontal scrub, cross-brush, and mini-scrub used respectively in Al-Jundi et al Helderman et al, Frazao, and Schwartz et al. are all accepted as standardized approaches, the choice of technique often depends on factors like individual’s age, manual dexterity, and personal capabilities [1, 12–14]. However, four of the included studies did not mention the brushing technique, while others characterized the specifics inconsistently [10, 11, 15, 16]. Because of the limited number of studies and the missing reporting of brushing techniques in several trials, we were unable to compare results across studies or incorporate brushing methodologies into the quantitative analysis. Future research should provide a comprehensive description of brushing techniques to facilitate comparability and synthesis across trials.

Furthermore, we were unable to examine grey literature, which could have provided a more comprehensive understanding of the effects of STB. The meta-analysis’s capacity to draw definitive conclusions is further restricted by the relatively low number of studies that were included.

To improve the quality of future evidence, studies should prioritize more rigorous designs with the standardized protocols and comprehensive reporting. Furthermore, incorporating both DMFT/dmft and DMFS/dmfs indices could provide a more precise understanding of the impact of STB on oral health, given the distinct advantages of each measure in capturing different aspects of caries progression.

Supervised toothbrushing has the potential to be integrated into national school health policies, particularly in regions with restricted access to dental care. To make this program grow in large scale, collaboration among the ministries of health and education is essential. Involving trained teachers or school nurses, including toothbrushing in daily school routines, and supplying fluoride toothpaste through public health systems help improve the effectiveness of such programs. Nonetheless, more rigorous research using standardized methodologies are essential to corroborate these results and investigate the long-term advantages of STB on both dental and surface-level outcomes.

Conclusion

This systematic review and meta-analysis indicate that school-based STB intervention may significantly diminish dental caries at the individual tooth surface level, as seen by the notable decrease in DMFS/dmfs indices. However, the absence of a statistically significant effect on DMFT/dmft indices suggests that the broader impact on whole-tooth caries may be less pronounced or may require longer follow-up periods to become apparent. These results support the potential of STB as a practical, scalable, and preventive strategy for improving children’s oral health, particularly in school-based settings where consistent habits can be reinforced over time.

Abbreviations

dmft

decayed, missing, and filled teeth, primary teeth

dmfs

decayed, missing, and filled surfaces, primary teeth

DMF

Decayed, missing, and filled, permanent teeth

DMFT

Decayed, missing, and filled teeth, permanent teeth

DMFS

Decayed, missing, and filled surfaces, permanent teeth

DFS

Decayed and filled surfaces

PPM

Parts per million,fluoride concentration

STB

School-Based Supervised Tooth Brushing

RCT

Randomized Controlled Trial

RoB

Risk of Bias

WHO

World Health Organization

OHID

Office for Health Improvement and Disparities

PRISMA

Preferred Reporting Items for Systematic Reviews and Meta-Analyses

OSF

Open Science Framework

defs

decayed, extracted, and filled surfaces (for primary dentition)

SMD

Standardized Mean Difference

SD

Standard Deviation

CI

Confidence Interval

SE

Standard Error

Sh.T

Shaghayegh Tavakoli

NS

Navid Saadatfar

AT

Amir Tiyuri

Authors’ contributions

Conceptualization, Sh.T; NS; methodology, Sh.T; NS; validation, NS; analysis, AT; investigation, Sh.T; data curation, Sh.T;NS; writing—original draft preparation, Sh,T; supervision, NS;AT. All authors have read and agreed to the final version of the manuscript.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author (Navid Saadatfar, Email: navid26268@gmail.com) on reasonable request.

Declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Birjand University of Medical Sciences with the ethical approval code [IR.BUMS.REC.1403.154]. All study procedures adhered to the guidelines of the institutional and national research ethics committees.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.