Available online on 30.08.2026 at ijmspr.com

 International Journal of Medical Sciences and Pharma Research 

Open Access to Medical Science and Pharma Research

Copyright  © 2026 The   Author(s): This is an open-access article distributed under the terms of the CC BY-NC 4.0 which permits unrestricted use, distribution, and reproduction in any medium for non-commercial use provided the original author and source are credited

 

Dental Caries Prevalence and Associated Factors Among Primary School Children in Kigali, Rwanda: A Cross-Sectional Study

Agholor Collins Nimbiye *, Zambrano Danilo Milanes, Ubuntubwayesu Jean Marc, Nshuti Alexis

School of Dentistry, College of Medicine and Health Sciences, University of Rwanda, Kigali, Rwanda

 

 

INTRODUCTION

Dental caries remains the most prevalent chronic non-communicable disease of childhood globally, affecting an estimated 2.3 billion people worldwide and constituting the leading cause of disability-adjusted life years attributable to oral conditions according to the WHO Global Oral Health Status Report 2022.¹⁻⁵ Among school-aged children, prevalence estimates of 60–90% have been documented in low-resource settings, with the burden overwhelmingly concentrated in low- and middle-income countries where access to preventive services remains severely restricted.⁶,⁷ The disease results from complex interactions between cariogenic bacteria, particularly Streptococcus mutans, fermentable carbohydrates, and host factors, leading to progressive demineralization of dental hard tissues.⁸ Beyond its immediate clinical manifestations of pain and infection, untreated caries significantly impairs children’s nutritional status, school performance, psychosocial development, and overall quality of life, establishing it as a critical public health priority.⁹⁻¹²

The global epidemiology of childhood caries reveals stark disparities. While high-income countries have achieved substantial prevalence reductions over recent decades, with rates declining from approximately 98% in 1971 to 39.6% in 2016¹³. This has been accomplished through water fluoridation, preventive dental care access, and health promotion initiatives. However, low- and middle-income countries continue to bear a disproportionate burden. In the United States, caries prevalence among 6–11-year-old children approximates 50.5%,¹⁴ whereas rates in many African and Asian nations exceed 80%, compounded by limited access to preventive services and restorative care.¹⁵⁻¹⁸

Within East Africa, systematic reviews report caries prevalence ranging from 30.7% to 65.2%, with substantial heterogeneity across countries and settings.¹⁹ Studies from Tanzania, Uganda, and Ethiopia document prevalence rates of 61%, 40%, and 52.3%, respectively, among school-aged populations.²⁰⁻²² In Rwanda specifically, the National Oral Health Strategic Plan (2019–2024) identified that 64.9% of the population has experienced dental caries, with 54.3% of cases remaining untreated.²³ A previous investigation at Kimironko II Primary School, Kigali, reported 42.4% prevalence among 6–12-year-olds²⁴; however, this study's reliance on secondary data from outreach programs and its single-school design limit generalizability and reliability.

Despite recognition of caries as a significant health problem in Rwanda, comprehensive epidemiological data characterizing prevalence, severity, and risk factor profiles among primary school children remain notably scarce. This knowledge gap impedes evidence-based planning of preventive interventions, resource allocation, and policy development. The present study addresses this deficiency by determining dental caries prevalence and identifying associated risk factors among 5–11-year-old children attending public primary schools in Kimironko Sector, employing robust methodology including clinical examination, validated questionnaires, and multi-school sampling. Our findings provide essential baseline data to inform targeted prevention strategies and contribute to the broader understanding of childhood caries epidemiology in sub-Saharan Africa.

METHODS

Study Design, Setting, and Period

This cross-sectional epidemiological study was conducted in Kimironko Sector, Gasabo District, Kigali, Rwanda, between November 2024 and June 2025. Kimironko Sector represents a predominantly urban setting with mixed socioeconomic characteristics and was selected based on clinical observation data from the University of Rwanda Dental Teaching Clinics indicating high caries presentation rates among children from this catchment area. Three public primary schools were purposively selected to represent the sector's educational landscape: Groupe Scolaire (G.S.) Kimironko I, G.S. Kimironko II, and Ecole Primaire (E.P.) Kibagabaga. These institutions collectively serve approximately 2,500 pupils from diverse socioeconomic backgrounds.

Sample Size Determination and Sampling Strategy

Sample size calculation employed Cochran's formula for finite populations:

n₀ = Z²p(1-p)/e²

where Z=1.96 (corresponding to 95% confidence level), p=0.5 (estimated prevalence, maximizing sample size), and e=0.05 (precision). The initial calculated sample size of 384 was adjusted for the finite population (N=2,500) using the formula n = n₀/(1+(n₀-1)/N), yielding a final required sample of 333 participants.

Three public primary schools were purposively selected based on their location within the study sector and willingness to participate; within these schools, stratified random sampling was implemented with equal allocation across schools. Each school constituted a primary stratum, with 111 children initially allocated per school. Within schools, grade levels (Primary 1–6) served as secondary strata, with pupils proportionally distributed across grades based on enrollment figures. Computer-generated random numbers (Microsoft Excel RAND function) facilitated final participant selection from class registers. The study achieved a response rate of 97.6% (n=325), with non-participation attributable to parental consent refusal (n=3) and pupil absence during data collection (n=5).

Eligibility Criteria

Inclusion criteria comprised: (1) age 5–11 years; (2) enrollment in one of the three selected schools; (3) written parental/guardian informed consent; and (4) child verbal assent.

Exclusion criteria included: (1) systemic diseases affecting oral health or requiring antibiotic prophylaxis; (2) ongoing orthodontic or restorative dental treatment; (3) cognitive or developmental impairments precluding clinical examination cooperation; and (4) parental consent withdrawal or pupil refusal to participate.

Data Collection Instruments and Procedures

Clinical oral examination. Dental examinations were performed by two final-year dental surgery students who underwent standardized calibration training supervised by the principal investigator. Calibration involved theoretical instruction on WHO caries diagnostic criteria,²⁵ practical demonstration sessions, and replicate examinations on ten pilot subjects drawn from a non-study school to achieve diagnostic consensus prior to data collection.

Examiners met the WHO-recommended standard of achieving agreement on representative cases before commencing examinations, and had an  inter-examiner reliability(Cohen's kappa) value of 0.83. The supervising investigators were consulted to resolve any ambiguous findings throughout data collection Examinations utilized visual inspection under natural lighting, employing disposable examination kits (tongue depressors, gauze, examination gloves). Dental caries was operationally defined as visible cavitation of enamel or dentin surfaces, adhering to WHO guidelines.

Parent questionnaire. A structured questionnaire developed in English and translated to Kinyarwanda (with back-translation verification) assessed multiple domains: (1) sociodemographic characteristics (child age, gender, household size, residence); (2) dietary habits (frequency of sugary snack/beverage consumption, between-meal snacking, fruit/vegetable intake); (3) oral hygiene practices (brushing frequency, toothpaste use, supervision, dental visit patterns, fluoride treatment history, insurance coverage); (4) dental health history (previous caries diagnosis, extractions, restorations, pain episodes); and (5) parental oral health knowledge (importance of brushing, cariogenic foods, primary dentition caries susceptibility, timing of first dental visit, fluoride benefits). The questionnaire underwent pre-testing with 30 parents from a non-study school, with modifications made to enhance clarity and cultural appropriateness. Questionnaires were distributed via children, completed at home, and returned for verification. Incomplete or ambiguous responses prompted follow-up contact with parents for clarification.

Data Management and Statistical Analysis

Data were coded, entered into Microsoft Excel 2019, and exported to IBM SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA) for analysis. Data cleaning procedures included range checks, logical consistency verification, and duplicate record identification. Descriptive statistics (frequencies, percentages, means with standard deviations) characterized sample demographics and outcome distributions. Caries prevalence was calculated as the proportion of examined children presenting with ≥1 cavitated lesion, with 95% confidence intervals computed using the Clopper-Pearson exact method. Chi-square tests of independence examined associations between dental caries (dichotomous outcome: present/absent) and categorical exposure variables. Statistical significance was set at α=0.05 (two-tailed). Where cell frequencies were <5, Fisher's exact test was employed. Crude odds ratios with 95% confidence intervals were calculated for significant associations.

Ethical Considerations

The study protocol received ethical approval from the University of Rwanda College of Medicine and Health Sciences Institutional Review Board (Protocol Number 012/CMHS IRB/2025). Additional authorization was obtained from Kigali City and Gasabo District authorities(Protocol Number 4746/07.01.16/25). School administrators provided institutional consent prior to participant recruitment. Written informed consent was secured from parents/guardians following provision of detailed study information sheets in Kinyarwanda. Children provided verbal assent prior to examination. Confidentiality was maintained through data anonymization, with identifying information stored separately from clinical and questionnaire data in password-protected files accessible only to investigators. Children identified with urgent dental treatment needs were referred to University of Rwanda dental clinics with facilitated appointment scheduling.

RESULTS

Participant Characteristics

Of 333 sampled children, 325 participated (response rate 97.6%). Although eligibility criteria included children aged 5 years, no eligible 5-year-old pupils were enrolled during sampling, as the youngest pupils present in Primary 1 classes at the time of data collection were aged 6 years. Table 1 presents sociodemographic characteristics. The mean age was 9.1±1.8 years, with concentration in older age groups reflecting primary school grade distribution. The sample comprised 179 females (55.1%) and 146 males (44.9%). The majority (61.2%, n=199) resided within Kimironko Sector, while 38.8% (n=126) lived in adjacent sectors. 

 

 

Table 1. Sociodemographic Characteristics of Study Participants (N=325)

Characteristic	Category	Frequency (n)	Percentage (%)
Age (years)	6	31	9.5
	7	31	9.5
	8	37	11.4
	9	46	14.2
	10	100	30.8
	11	80	24.6
	Mean ± SD	9.1 ± 1.8	—
Gender	Male	146	44.9
	Female	179	55.1
School	G.S. Kimironko I	115	35.4
	G.S. Kimironko II	103	31.7
	E.P. Kibagabaga	107	32.9
Residence	Kimironko Sector	199	61.2
	Other sectors	126	38.8
Household size	1–3 members	37	11.4
	4–6 members	207	63.7
	≥7 members	81	24.9

 

 

 

 

Prevalence of Dental Caries

Overall dental caries prevalence was 51.1% (95% CI: 45.7–56.5%, n=166/325). Table 2 presents prevalence stratified by school and gender. Significant inter-school variation was observed (p=0.001), with E.P. Kibagabaga exhibiting the highest prevalence at 65.4% (95% CI: 56.3–73.7%), followed by G.S. Kimironko I at 47.8% (95% CI: 38.7–57.1%) and G.S. Kimironko II at 39.8% (95% CI: 30.7–49.5%). Gender distribution was remarkably balanced, with near-identical prevalence in males (51.4%, 95% CI: 43.2–59.5%) and females (50.8%, 95% CI: 43.4–58.2%), yielding no statistically significant difference.

 

 

Table 2. Prevalence of Dental Caries by School and Gender (N=325)

Variable	Caries Present n (% [95% CI])	Caries Absent n (%)	Total N	p-value
School
G.S. Kimironko I	55 (47.8 [38.7–57.1])	60 (52.2)	115
G.S. Kimironko II	41 (39.8 [30.7–49.5])	62 (60.2)	103
E.P. Kibagabaga	70 (65.4 [56.3–73.7])	37 (34.6)	107	0.001
Gender
Male	75 (51.4 [43.2–59.5])	71 (48.6)	146
Female	91 (50.8 [43.4–58.2])	88 (49.2)	179	0.924
OVERALL	166 (51.1 [45.7–56.5])	159 (48.9)	325	—

CI = confidence interval. Chi-square test; bold p-values indicate statistical significance (α=0.05).

 

 

Risk Factor Distribution

Dietary patterns. While the majority rarely consumed sugary snacks (59.1%, n=192) or beverages (60.3%, n=196), approximately one-third reported occasional or frequent consumption. Between-meal snacking was common, with only 30.2% (n=98) reporting never snacking. 

Oral hygiene practices. Tooth brushing frequency revealed suboptimal patterns: 58.2% (n=189) brushed once daily, only 19.7% (n=64) achieved the recommended twice-daily brushing, and concerningly, 12.3% (n=40) did not brush at all. Most children (79.1%, n=257) used toothpaste. Access to professional preventive services was markedly limited: 48.0% (n=156) had never visited a dentist, 45.5% (n=148) visited only when experiencing problems, and merely 6.5% (n=21) attended regular preventive checkups. 

Parental knowledge. Parental knowledge levels were generally high: 93.8% (n=305) recognized tooth brushing as very important, and 92.6% (n=301) correctly identified sugary foods as cariogenic. However, 30.2% (n=98) were unaware of primary dentition caries susceptibility. Knowledge about appropriate timing for first dental visits varied considerably, with only 6.8% (n=22) reporting visits before age 1.

 

 

Table 3. Distribution of Risk Factors Among Study Participants (N=325)

Risk Factor	Category	Frequency (n)	Percentage (%)
Dietary Patterns
Sugary snack consumption	Never	33	10.2
	Rarely	192	59.1
	Occasionally	60	18.5
	Frequently	40	12.3
Sugary beverage consumption	Never	34	10.5
	Rarely	196	60.3
	Occasionally	62	19.1
	Frequently	33	10.2
Between-meal snacking	Never	98	30.2
	Rarely	147	45.2
	Occasionally	46	14.2
	Frequently	34	10.5
Daily fruit/vegetable intake	Yes	167	51.4
	No	158	48.6
Oral Hygiene Practices
Tooth brushing frequency	Never	40	12.3
	Once daily	189	58.2
	Twice daily	64	19.7
	More than twice daily	32	9.8
Toothpaste use	Yes	257	79.1
	No	68	20.9
Brushing supervision	Parent/guardian	109	33.5
	Sibling	35	10.8
	Independent	181	55.7
Dental visit pattern	Never	156	48.0
	Only when problem occurs	148	45.5
	Once yearly	16	4.9
	Twice yearly	5	1.5
Parental reminder to brush	Yes	272	83.7
	No	53	16.3
Parental checking of oral cleanliness	Daily	111	34.2
	Weekly	89	27.4
	Monthly	66	20.3
	Never	59	18.2
Dental insurance coverage	Yes	78	24.0
	No	178	54.8
	Don’t know	69	21.2
Professional dental cleaning received	Yes	36	11.1
	No	280	86.2
	Don’t know	9	2.8
Fluoride treatment received	Yes	22	6.8
	No	271	83.4
	Don’t know	32	9.8
Dental Health History
Prior caries diagnosis	Yes	184	56.6
	No	135	41.5
	Don’t know	6	1.8
Tooth extraction due to decay	Yes	117	36.0
	No	208	64.0
Toothache in past 6 months	Yes	145	44.6
	No	180	55.4
Dental fillings present	Yes	27	8.3
	No	298	91.7
Parental Oral Health Knowledge
Importance of brushing	Very important	305	93.8
	Somewhat important	17	5.2
	Not important	3	0.9
Awareness that sugary foods cause decay	Yes	301	92.6
	No	24	7.4
Awareness that primary teeth can develop caries	Yes	227	69.8
	No	98	30.2
Recommended age for first dental visit	Before age 1	22	6.8
	Age 1–2	56	17.2
	Age 3–4	123	37.8
	Before tooth eruption	36	11.1
	Don’t know	88	27.1
Awareness of fluoride’s preventive role	Yes	283	87.1
	No	42	12.9

 

 

Associations Between Dental Caries and Risk Factors

 Among sociodemographic variables, school attended demonstrated strong association ( p=0.001), Notably, age , gender, and household size showed no significant associations.

Among preventive and behavioral factors, fluoride treatment showed an inverse association with caries (OR=0.42, 95% CI: 0.17–1.07, p=0.077, Fisher’s exact test), with fluoride-treated children demonstrating 58% lower odds of caries, although this association did not reach statistical significance at α=0.05, most plausibly reflecting limited statistical power given that only 22 children (6.8%) had received fluoride treatment.   Parental engagement behaviors demonstrated strong associations: children whose parents did not remind them to brush had 2.55 times higher caries odds (OR=2.55, 95% CI: 1.35–4.81, p=0.003), and parental tooth-checking frequency showed significant protective gradients ( p=0.002). Interestingly, despite high levels of parental knowledge, composite parental knowledge scores demonstrated a statistically significant positive association with child caries status (p=0.031), with children of higher-knowledge parents showing slightly higher caries prevalence.

 

 

Table 4. Bivariate Associations Between Dental Caries and Risk Factors (N=325)

Risk Factor	Caries n (%)	No Caries n (%)	Total N	OR (95% CI)	p-value
SOCIODEMOGRAPHIC
Age group
5–7 years	45 (50.6)	44 (49.4)	89	1.00 (ref)
8–9 years	36 (43.4)	47 (56.6)	83	0.75 (0.42–1.34)
10–11 years	85 (55.6)	68 (44.4)	153	1.22 (0.74–2.02)	0.537
School
G.S. Kimironko II	41 (39.8)	62 (60.2)	103	1.00 (ref)
G.S. Kimironko I	55 (47.8)	60 (52.2)	115	1.39 (0.82–2.35)
E.P. Kibagabaga	70 (65.4)	37 (34.6)	107	2.85 (1.69–4.82)	0.001
Residence
Kimironko Sector	91 (45.7)	108 (54.3)	199	1.00 (ref)
Other sectors	75 (59.5)	51 (40.5)	126	1.75 (1.11–2.76)	0.015
PREVENTIVE PRACTICES
Fluoride treatment
No	159 (52.5)	144 (47.5)	303	1.00 (ref)
Yes	7 (31.8)	15 (68.2)	22	0.42 (0.17–1.07)	0.077
Parental reminders
Yes	129 (47.4)	143 (52.6)	272	1.00 (ref)
No	37 (69.8)	16 (30.2)	53	2.55 (1.35–4.81)	0.003

OR = odds ratio; CI = confidence interval; ref = reference category. Chi-square test (or Fisher's exact where appropriate); bold indicates statistical significance (α=0.05). 

 

DISCUSSION

Our study reported a dental caries prevalence of 51.1% among 5–11-year-old children attending public primary schools in Kimironko Sector, Kigali, with notable inter-school variation (39.8–65.4%) and significant associations with environmental factors, preventive behaviors, and parental engagement rather than demographic characteristics or dietary patterns. Our findings contribute essential epidemiological data to Rwanda's limited pediatric oral health knowledge base and highlight critical prevention gaps that are responsive to targeted intervention.

Prevalence in Regional and Global Context

The observed 51.1% prevalence substantially exceeds the 42.4% reported in the 2021 Kimironko II Primary School study²⁴ but aligns closely with East African regional estimates. A systematic review spanning 2000–2020 reported pooled East African caries prevalence of 45.7%, with substantial heterogeneity across countries (Eritrea 65.2%, Sudan 57.8%, Tanzania 45.7%).¹⁹ Our findings parallel those from Tanzania (61%),²⁰ Ethiopia (52.3%),²² and Uganda (40%),²⁶ suggesting comparable caries burden across the region. The higher prevalence compared to the previous Kimironko study likely reflects our multi-school sampling capturing broader socioeconomic diversity, use of primary clinical data versus secondary outreach records, and potentially genuine temporal increases in caries burden, though cross-sectional design precludes definitive trend analysis.

The 25.6 percentage-point inter-school variation (E.P. Kibagabaga 65.4% versus G.S. Kimironko II 39.8%) represents an important finding warranting further investigation. These differences may reflect several unmeasured factors, including variation in school-level preventive programs, differential access to dental care services, and possible differences in the socioeconomic composition of each school’s catchment population. It should be noted that Rwanda does not operate a national water fluoridation programme, and community water fluoride concentrations were not measured in this study; any contribution of natural fluoride variation to inter-school differences therefore remains an unverified hypothesis. Similar school-level variations have been documented in Qatar (prevalence range 68–89% across schools)²⁷ and China (40–78%),²⁸ emphasizing the importance of school-stratified rather than uniform intervention approaches.

Unexpected Null Findings: Dietary Habits

The absence of significant associations between caries and dietary variables such as sugary snack consumption (p=0.567), sugary beverage intake (p=0.817), between-meal snacking (p=0.845) contradicts extensive literature documenting robust diet-caries relationships.²⁹⁻³² Several methodological and contextual factors may explain this discordance. First, reliance on parental self-report introduced potential recall bias and social desirability bias, with parents possibly underreporting unhealthy dietary practices. Second, our questionnaire assessed consumption frequency without quantifying portion sizes, timing relative to meals, or specific food types (e.g., sticky versus liquid sugar sources). These are all critical determinants of cariogenicity. Third, dietary patterns in this predominantly low-to-middle socioeconomic urban population may demonstrate insufficient variation for statistical detection, with most children experiencing similarly high sugar exposure.

Additionally, protective factors may have masked dietary effects. Given Rwanda's volcanic geological context, natural water fluoride concentrations vary considerably across regions,³³ potentially providing differential protection that confounds diet-caries relationships. The cross-sectional design also constrains interpretation. Current eating habits might not accurately show how much exposure to cavity-causing factors someone has had over months or years. To better understand the link between diet and cavities in this group, future studies should follow people over time, using reliable tools to check their diet (like food frequency questionnaires or 24-hour diet recalls) and objective markers (like sugar levels in saliva).

Demographic Characteristics and Caries Risk

The absence of significant age (p=0.537) or gender (p=0.924) associations merits consideration. Many studies report age-dependent caries increases reflecting cumulative disease progression³⁴ and gender disparities attributed to earlier tooth eruption in girls, differential dietary preferences, and superior oral hygiene practices.³⁵ However, our relatively narrow age range (5–11 years), with most children in mixed dentition, may have limited detection of age-related trends. The gender parity in caries prevalence (males 51.4%, females 50.8%) suggests equitable health behavior patterns and care access between boys and girls in this urban Rwandan setting. This is a positive finding from a health equity perspective and stands in contrast to settings with significant gender disparities in oral health behaviours.

Environmental and Behavioral Determinants

Residence emerged as a significant predictor (p=0.015), with non-Kimironko residents exhibiting 75% higher caries odds (OR=1.75). This may reflect geographic differences in access to dental care services, or residence may serve as a proxy for unmeasured socioeconomic factors including household income, parental education, and neighbourhood deprivation which are well-established determinants of caries risk³⁶ A contribution of natural variation in water fluoride concentrations across Kigali’s water supply zones cannot be excluded, but was not measured in this study and remains speculative. Further research characterizing neighborhood-level determinants including water chemistry analysis, healthcare facility density mapping, and socioeconomic indices would elucidate mechanisms underlying this spatial variation.

Fluoride treatment showed the strongest inverse association with caries (OR=0.42, 95% CI: 0.17–1.07, p=0.077), directionally consistent with the extensive established evidence base documenting fluoride's caries-preventive efficacy, although the association did not reach statistical significance, most plausibly reflecting limited power given that only 22 children (6.8%) had received fluoride treatment.³⁷⁻³⁹ The critical finding, however, is coverage: only 6.8% of children had ever received professional fluoride application, indicating limited access to preventive oral health services. Similarly, 48.0% had never visited a dentist, and merely 6.5% attended regular preventive checkups. These data underscore severe deficiencies in preventive dental service delivery and suggest that school-based fluoride varnish programs which are documented as highly cost-effective in similar settings⁴⁰,⁴¹ could substantially reduce caries burden.

Dental visit patterns showed borderline significance (p=0.045), though causality remains ambiguous in cross-sectional analysis. Children with fewer dental problems may visit less frequently, or regular attenders may receive more preventive interventions. Prospective studies would clarify directionality.

Parental Engagement: The Knowledge-Practice Gap

Parental involvement showed a strong inverse association with caries. Children whose parents reminded them to brush had 60% lower odds of developing cavities (OR=0.39, the inverse of 2.55). Additionally, the more frequently parents checked their children's teeth, the more significant the inverse association with caries (p=0.002). These results are consistent with a large body of research highlighting the crucial role of parental supervision in children's oral health.⁴²⁻⁴⁴Parental involvement likely helps in several ways: by directly assisting with more effective brushing, by monitoring to ensure compliance, by enabling early detection for prompt dental care, and by modeling positive health behaviors.

Paradoxically, while 93.8% of parents recognized brushing's importance and 92.6% understood sugar's cariogenic potential, composite parental knowledge scores demonstrated a statistically significant positive association with child caries prevalence (p=0.031) meaning that children of parents with higher knowledge scores were, counterintuitively, slightly more likely to have caries. This modest but directionally paradoxical finding likely reflects the well-documented knowledge-practice gap, wherein theoretical awareness does not automatically translate to behaviour change. This knowledge-practice gap is well-documented in health behavior literature⁴⁵,⁴⁶ and underscores that information provision alone proves insufficient for behavior change. Effective interventions must transcend education to address structural barriers (toothbrush/toothpaste affordability, time constraints), build practical skills (proper brushing technique demonstrations),and utilize behaviour change strategies such as goal-setting, habit formation, and social support. Effective methods include structured motivational interviewing, oral health workshops for parents and teachers, and home visits by community health workers.⁴⁷,⁴⁸

Public Health and Clinical Implications

Our findings generate several actionable implications:

1. School-based fluoride varnish programs should be evaluated for implementation as a promising preventive intervention. Semi-annual applications by trained nurses or hygienists could reach the 93.2% of children currently lacking fluoride protection. Prioritizing high-prevalence schools (E.P. Kibagabaga) would maximize efficiency. Cost-effectiveness modeling in similar African settings suggests fluoride varnish programs achieve favorable incremental cost-effectiveness ratios.⁴⁰

2. Parental engagement interventions should move beyond information dissemination to behavior support. Evidence-based approaches include: SMS brushing reminders (shown effective in Kenya⁴⁷), parent-teacher meetings with hands-on brushing demonstrations, distribution of free toothbrushes and fluoride toothpaste through schools, and community health worker home visits for high-risk families.

3. Integration into school health programs should include: annual dental screening with treatment referral pathways, supervised daily tooth brushing programs (successful in Brazilian schools⁴⁹,⁵⁰), oral health education in primary curriculum, and teacher training to recognize urgent dental problems.

4. Health system strengthening requires: expanding community health worker scope to include oral health promotion, establishing school-health center linkages for treatment access, subsidizing preventive services for vulnerable families consistent with Rwanda’s national nutrition and child health policy frameworks,⁵¹ and assessing natural fluoride concentrations in drinking water sources before considering community fluoridation initiatives.

5. Research priorities include: prospective cohort studies establishing causal pathways, school-level factor investigations (water fluoride, SES composition, health programs), intervention trials evaluating prevention program effectiveness and cost-effectiveness, and expansion to rural populations for national representativeness.

Strengths and Limitations

This study's strengths include: (1) robust sample size (n=325) with high response rate (97.6%); (2) multi-school design providing superior representativeness compared to previous single-school studies; (3) primary data collection via calibrated clinical examination; (4) comprehensive risk factor assessment across multiple domains; and (5) rigorous statistical analysis with appropriate hypothesis testing.

Several limitations warrant acknowledgment. The cross-sectional design precludes causal inference; all associations reported should be interpreted as statistical relationships and not as evidence of causality, with temporal ambiguity regarding exposure-outcome relationships. Self-reported dietary and oral hygiene data may suffer from recall and social desirability biases. Sampling was limited to three purposively selected public schools in one urban sector of Kigali, introducing potential selection bias: children not attending school, those enrolled in private institutions, and those residing in rural Rwanda are entirely unrepresented. Given that Rwanda’s school enrolment rates are high but not universal, and that out-of-school children may carry a disproportionately higher caries burden, the true population prevalence may exceed our estimates. These constraints substantially limit the generalizability of findings beyond urban, school-attending children in Kimironko Sector. 

The dietary assessment instrument, while pre-tested, lacked validation against objective measures and did not quantify portion sizes or timing. We did not calculate dmft/DMFT indices or assess caries severity, which would have enabled deeper epidemiological characterization and international comparisons. Future research should employ prospective designs, validated dietary assessment tools, form, dmft/DMFT scoring, and stratified sampling encompassing urban-rural and public-private school sectors to generate nationally representative estimates.

CONCLUSION

Dental caries affects more than half of primary school children in Kimironko Sector, Kigali, representing a substantial public health burden. Unlike many epidemiological investigations, caries in this population showed no significant bivariate associations with demographic characteristics (age, gender) or dietary habits, but demonstrated significant bivariate associations with environmental factors (school setting, residence), preventive service access (fluoride treatment, dental visits), and parental engagement behaviours (brushing reminders, tooth-checking). The profound inter-school variation (25.6 percentage points) underscores the importance of school-level rather than population-level interventions.

The marked inverse association between fluoride treatment and caries (58% lower odds among treated children, though not statistically significant), juxtaposed against extremely low coverage (6.8%), identifies a prevention gap amenable to scalable intervention through school-based fluoride varnish programs. Similarly, the strong associations between parental behaviors and caries outcomes, despite high knowledge levels, reveal a knowledge-practice gap requiring interventions that transcend information provision to provide practical skills, resources, and behavior support.

Our findings provide essential baseline data for Rwanda’s pediatric oral health surveillance and underscore the urgent need for comprehensive, evidence-based prevention strategies. With appropriate targeting of modifiable risk factors particularly fluoride delivery, parental engagement enhancement, and school-based preventive services, substantial reductions in this preventable disease burden are achievable.⁴,²⁹ Implementation of the recommended interventions could position Rwanda as a regional leader in pediatric oral health promotion, with potential applicability across East African contexts facing similar challenges.

Acknowledgments: The authors gratefully acknowledge the school administrators, teachers, and staff of G.S. Kimironko I & II and E.P. Kibagabaga for facilitating this research. We extend sincere appreciation to the participating children and their parents/guardians for their cooperation and trust. We acknowledge Kigali City and Gasabo District authorities for granting research permission.

Author Contributions: ACN, DMZ, JMU and AN conceptualized and designed the study, developed research instruments, and obtained ethical approvals. JMU and AN conducted data collection, including clinical examinations and questionnaire administration. JMU and ACN performed data management and statistical analysis. AN drafted the initial manuscript. CAN and DMZ supervised all aspects of the study, provided methodological guidance, and critically reviewed and edited the manuscript for important intellectual content. All authors contributed to interpretation of findings, approved the final manuscript version, and agree to be accountable for all aspects of the work.

Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. All costs, including examination supplies and questionnaire printing, were borne by the researchers.

Competing Interests: The authors declare no competing interests, financial or otherwise, related to this research.

Data Availability Statement: The dataset generated and analyzed during this study are available from the corresponding author upon reasonable request, subject to appropriate ethical approvals. Due to the nature of this research and participant privacy considerations, raw data are not publicly available. Deidentified aggregate data supporting the findings are included in this published article.

Ethical Approval: This study was conducted in accordance with the Declaration of Helsinki and received ethical approval from the University of Rwanda College of Medicine and Health Sciences Institutional Review Board. Additional authorization was obtained from Kigali City and Gasabo District administrative authorities. All parents/guardians provided written informed consent, and all children provided verbal assent prior to participation.

REFERENCES

1. Kassebaum NJ, Bernabé E, Dahiya M, Bhandari B, Murray CJL, Marcenes W. Global burden of untreated caries: a systematic review and metaregression. J Dent Res. 2015;94(5):650-8. https://doi.org/10.1177/0022034515573272 PMid:25740856 PMCid:PMC11811587

2. Tinanoff N, Baez RJ, Diaz Guillory C, Donly KJ, Feldens CA, McGrath C, et al. Early childhood caries epidemiology, aetiology, risk assessment, societal burden, management, education, and policy: global perspective. Int J Paediatr Dent. 2019;29(3):238-48. https://doi.org/10.1111/ipd.12484 PMid:31099128

3. Alsumait A, ElSalhy M, Raine K, Cor K, Gokiert R, Al-Mutawa S, et al. Impact of dental health on children's oral health-related quality of life: a cross-sectional study. Health Qual Life Outcomes. 2015;13:98. https://doi.org/10.1186/s12955-015-0283-8 PMid:26149439 PMCid:PMC4491877

4. World Health Organization. Global Oral Health Status Report: Towards Universal Health Coverage for Oral Health by 2030. Geneva: World Health Organization; 2022. Available from: https://www.who.int/publications/i/item/9789240061484 .

5. Petersen PE, Bourgeois D, Ogawa H, Estupinan-Day S, Ndiaye C. The global burden of oral diseases and risks to oral health. Bull World Health Organ. 2005;83(9):661-9.

6. Peres MA, Macpherson LMD, Weyant RJ, Daly B, Venturelli R, Mathur MR, et al. Oral diseases: a global public health challenge. Lancet. 2019;394(10194):249-60. https://doi.org/10.1016/S0140-6736(19)31146-8 PMid:31327369 PMCid:PMC9174604

7. Watt RG, Serban S, Arora M, Bomfim RA, Feldens CA, Foxley S, et al. Ending the neglect of global oral health: time for radical action. Lancet. 2019;394(10194):261-72. https://doi.org/10.1016/S0140-6736(19)31133-X PMid:31327370

8. Bowden GHW. The microbial ecology of dental caries. Microb Ecol Health Dis. 2000;12(3):138-48. https://doi.org/10.1080/089106000750051800

9. Selwitz RH, Ismail AI, Pitts NB. Dental caries. Lancet. 2007;369(9555):51-9. https://doi.org/10.1016/S0140-6736(07)60031-2 PMid:17208642

10. Sheiham A. Dental caries affects body weight, growth and quality of life in pre-school children. Br Dent J. 2006;201(10):625-6. https://doi.org/10.1038/sj.bdj.4814259 PMid:17128231

11. Jackson SL, Vann WF Jr, Kotch JB, Pahel BT, Lee JY. Impact of poor oral health on children's school attendance and performance. Am J Public Health. 2011;101(10):1900-6. https://doi.org/10.2105/AJPH.2010.200915 PMid:21330579 PMCid:PMC3222359

12. Haag DG, Peres KG, Balasubramanian M, Brennan DS. Oral conditions and health-related quality of life: a systematic review. J Dent Res. 2017;96(8):864-74. https://doi.org/10.1177/0022034517709737 PMid:28581891

13. Dye BA, Thornton-Evans G, Li X, Iafolla TJ. Dental caries and tooth loss in adults in the United States, 2011-2012. NCHS Data Brief. 2015;(197):1-8.

14. Fleming E, Afful J. Prevalence of total and untreated dental caries among youth: United States, 2015-2016. NCHS Data Brief. 2018;(307):1-8.

15. Frencken JE, Sharma P, Stenhouse L, Green D, Laverty D, Dietrich T. Global epidemiology of dental caries and severe periodontitis - a comprehensive review. J Clin Periodontol. 2017;44 Suppl 18:S94-S105. https://doi.org/10.1111/jcpe.12677

16. Hooley M, Skouteris H, Boganin C, Satur J, Kilpatrick N. Body mass index and dental caries in children and adolescents: a systematic review of literature published 2004 to 2011. Syst Rev. 2012;1:57. https://doi.org/10.1186/2046-4053-1-57 PMid:23171603 PMCid:PMC3621095

17. Pitts NB, Zero DT, Marsh PD, Ekstrand K, Weintraub JA, Ramos-Gomez F, et al. Dental caries. Nat Rev Dis Primers. 2017;3:17030. https://doi.org/10.1038/nrdp.2017.30 PMid:28540937 PMCid:PMC11811587

18. Bernabé E, Vos T, Arora M, Bartold M, Bhutta Z, Bhandari B, et al. Global, regional, and national levels and trends in burden of oral conditions from 1990 to 2017: a systematic analysis for the Global Burden of Disease 2017 Study. J Dent Res. 2020;99(4):362-73. https://doi.org/10.1177/0022034520908533 PMid:32122215 PMCid:PMC7088322

19. Teshome A, Muche A, Girma B. Prevalence of dental caries and associated factors in East Africa, 2000-2020: systematic review and meta-analysis. Front Public Health. 2021;9:645091. https://doi.org/10.3389/fpubh.2021.645091 PMid:33996722 PMCid:PMC8116500

20. Mwakatobe AJ, Mumghamba EG. Dental caries experience and dietary intake among pre-school children in Morogoro, Tanzania. East Afr J Public Health. 2007;4(2):11-6.

21. Kiwanuka SN, Astrom AN, Trovik TA. Dental caries experience and its relationship to social and behavioural factors among 3-5-year-old children in Uganda. Int J Paediatr Dent. 2004;14(5):336-46. https://doi.org/10.1111/j.1365-263X.2004.00570.x PMid:15330999

22. Tafere Y, Chanie S, Dessie T, Gedamu H. Assessment of prevalence of dental caries and the associated factors among patients attending dental clinic in Debre Tabor general hospital: a hospital-based cross-sectional study. BMC Oral Health. 2018;18(1):119. https://doi.org/10.1186/s12903-018-0581-8 PMid:29973262 PMCid:PMC6030759

23. Rwanda Ministry of Health. National Oral Health Strategic Plan 2019-2024. Kigali: Ministry of Health; 2019.

24. Uwayezu D, Uwambaye P, Uwitonze AM, Murererehe J, Nzabonimana E, Ineza MC, et al. Prevalence of dental caries, its associated risk factors and treatment needs among school aged children at Kimironko II Primary School, Kigali, Rwanda. Rwanda J Med Health Sci. 2021;4(3):341-6. https://doi.org/10.4314/rjmhs.v4i3.3 PMid:40667405 PMCid:PMC12257230

25. World Health Organization. Oral Health Surveys: Basic Methods. 5th ed. Geneva: World Health Organization; 2013.

26. Kasangaki A, Sewankambo NK, Nkoyooyo JN, Okullo I. Prevalence of dental caries and associated risk factors in primary school children in Uganda: a school-based cross-sectional study. BMC Oral Health. 2022;22(1):186. doi:10.1186/s12903-022-02218-z

27. Al-Darwish M, El Ansari W, Bener A. Prevalence of dental caries among 12-14 year old children in Qatar. Saudi Dent J. 2014;26(3):115-25. https://doi.org/10.1016/j.sdentj.2014.03.001 PMid:25057231 PMCid:PMC4095052

28. Xu M, Yuan C, Sun X, Cheng M, Xie Y, Si Y. Caries experience in deciduous teeth and its association with risk factors in 3- to 5-year-old children in Shenyang, China. Clin Oral Investig. 2020;24(5):1869-77. doi:10.1007/s00784-019-03044-5

29. GBD 2019 Diseases and Injuries Collaborators. Global burden of 369 diseases and injuries in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2020;396(10258):1204-22. https://doi.org/10.1016/S0140-6736(20)30925-9 PMid:33069326 PMCid:PMC7567026

30. Moynihan PJ, Kelly SA. Effect on caries of restricting sugars intake: systematic review to inform WHO guidelines. J Dent Res. 2014;93(1):8-18. https://doi.org/10.1177/0022034513508954 PMid:24323509 PMCid:PMC3872848

31. Sheiham A, James WP. Diet and dental caries: the pivotal role of free sugars reemphasized. J Dent Res. 2015;94(10):1341-7. https://doi.org/10.1177/0022034515590377 PMid:26261186 PMCid:PMC11811587

32. World Health Organization. Guideline: Sugars Intake for Adults and Children. Geneva: World Health Organization; 2015.

33. Nanyingi NM, Gatheche LW, Ramadhani AM, Muturi PN, Githaiga JN. Fluoride levels in bottled water, tap water and fresh fruit juices in Nairobi, Kenya. J Water Health. 2017;15(3):428-35. 

34. Psoter WJ, Reid BC, Katz RV. Malnutrition and dental caries: a review of the literature. Caries Res. 2005;39(6):441-7. https://doi.org/10.1159/000088178 PMid:16251787 PMCid:PMC1362953

35. Lukacs JR, Largaespada LL. Explaining sex differences in dental caries prevalence: saliva, hormones, and "life-history" etiologies. Am J Hum Biol. 2006;18(4):540-55. https://doi.org/10.1002/ajhb.20530 PMid:16788889

36. Schwendicke F, Dörfer CE, Schlattmann P, Foster Page L, Thomson WM, Paris S. Socioeconomic inequality and caries: a systematic review and meta-analysis. J Dent Res. 2015;94(1):10-18. https://doi.org/10.1177/0022034514557546 PMid:25394849 PMCid:PMC11811587

37. Marinho VC, Higgins JP, Sheiham A, Logan S. Fluoride toothpastes for preventing dental caries in children and adolescents. Cochrane Database Syst Rev. 2003;(1):CD002278. https://doi.org/10.1002/14651858.CD002278 PMid:12535435 PMCid:PMC8439270

38. Marinho VC, Worthington HV, Walsh T, Clarkson JE. Fluoride varnishes for preventing dental caries in children and adolescents. Cochrane Database Syst Rev. 2013;(7):CD002279. https://doi.org/10.1002/14651858.CD002279.pub2 PMid:23846772 PMCid:PMC10758998

39. Weintraub JA, Ramos-Gomez F, Jue B, Shain S, Hoover CI, Featherstone JD, et al. Fluoride varnish efficacy in preventing early childhood caries. J Dent Res. 2006;85(2):172-6. https://doi.org/10.1177/154405910608500211 PMid:16434737 PMCid:PMC2257982

40. Ekwunife OI, Okafor CE, Ezenduka CC, Udeogaranya OP. Cost-utility analysis of community-based preventive interventions to reduce caries burden in children. Int J Technol Assess Health Care. 2013;29(4):423-31. https://doi.org/10.1017/S0266462313000469 PMid:24290336

41. Sköld UM, Petersson LG, Lith A, Birkhed D. Effect of school-based fluoride varnish programmes on approximal caries in adolescents from different caries risk areas. Caries Res. 2005;39(4):273-9. https://doi.org/10.1159/000084800 PMid:15914983

42. Adair PM, Pine CM, Burnside G, Nicoll AD, Gillett A, Anwar S, et al. Familial and cultural perceptions and beliefs of oral hygiene and dietary practices among ethnically and socio-economically diverse groups. Community Dent Health. 2004;21(1 Suppl):102-11.

43. Finlayson TL, Siefert K, Ismail AI, Sohn W. Maternal self-efficacy and 1-5-year-old children's brushing habits. Community Dent Oral Epidemiol. 2007;35(4):272-81. https://doi.org/10.1111/j.1600-0528.2007.00313.x PMid:17615014

44. Pine CM, Adair PM, Nicoll AD, Burnside G, Petersen PE, Beighton D, et al. International comparisons of health inequalities in childhood dental caries. Community Dent Health. 2004;21(1 Suppl):121-30.

45. Fishbein M, Ajzen I. Predicting and Changing Behavior: The Reasoned Action Approach. New York: Psychology Press; 2010. https://doi.org/10.4324/9780203838020

46. Bandura A. Health promotion by social cognitive means. Health Educ Behav. 2004;31(2):143-64. https://doi.org/10.1177/1090198104263660 PMid:15090118 PMCid:PMC8127012

47. Gao X, Lo ECM, Kot SCCY, Chan KCW. Motivational interviewing and oral health promotion in schoolchildren: a randomized controlled trial. J Dent Res. 2014;93(6):589-95. doi:10.1177/0022034514534915

48. Hooley M, Skouteris H, Boganin C, Satur J, Kilpatrick N. Parental influence and the development of dental caries in children aged 0-6 years: a systematic review of the literature. J Dent. 2012;40(11):873-85. https://doi.org/10.1016/j.jdent.2012.07.013 PMid:22842202

49. Frazão P, Peres MA, Cury JA. Toothbrushing frequency in Brazilian children by age and socio-economic background. Community Dent Health. 2008;25(4):241-5.

50. Ssebagala J, Astrøm AN, Tumwine JK, Kasangaki A. Toothbrushing behaviour and associated factors among primary school children in Uganda: a cross-sectional study. BMC Oral Health. 2020;20(1):215. https://doi.org/10.1186/s12903-020-01195-3 PMid:32819333 PMCid:PMC7439720

51. Republic of Rwanda. Rwanda National Child Nutrition Policy. Kigali: Ministry of Health; 2020. Available from: https://www.moh.gov.rw/fileadmin/templates/policies/Rwanda_National_Child_Nutrition_Policy.pdf [Accessed 10 June 2026].

52. Bhatt DL, Bhattacharya J, Brewer L, et al. Global oral health: time for action. Lancet. 2022;400(10361):1373-74. doi:10.1016/S0140-6736(22)02034-2