A Systematic Review and Meta-analysis on the Epidemiology of Early Childhood Caries in Nigeria

doi:10.21203/rs.3.rs-5006258/v1

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A Systematic Review and Meta-analysis on the Epidemiology of Early Childhood Caries in Nigeria

https://doi.org/10.21203/rs.3.rs-5006258/v1

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Background

Early Childhood Caries (ECC) is a significant oral health issue affecting children under six years old. This study aimed to determine the prevalence and distribution of ECC in Nigeria through a systematic review and meta-analysis.

Methods

A systematic search was conducted across multiple databases for studies on ECC prevalence in Nigeria. The Joanna Briggs Institute (JBI) checklist was used to assess study quality. A random-effects model was employed to calculate pooled prevalence estimates and mean dmft scores. Subgroup analyses and meta-regression were performed to explore sources of heterogeneity.

Results

Twenty-three studies met the inclusion criteria, comprising 7,362 participants. The pooled ECC prevalence in Nigeria was 17% (95% CI: 11% – 24%), with significant heterogeneity (I² = 97%). Subgroup analyses revealed variations across geopolitical zones and study settings. The pooled mean dmft score was 0.44 (95% CI: 0.24–0.74). Age group and gender showed minimal impact on ECC prevalence.

Conclusion

With a 17% prevalence rate, ECC remains a significant public health concern in Nigeria. The study highlights the need for targeted interventions, standardized national surveys, and further research into region-specific risk factors to address ECC effectively.

Early Childhood Caries

Nigeria

Prevalence

Meta-Analysis

Systematic Review

Oral Health

Dental caries, commonly known as tooth decay, is the demineralization and eventual destruction of teeth due to acid production from oral microbial interactions with fermentable carbohydrate substrates.¹ Early Childhood Caries (ECC), a specific variant of dental caries, is characterized by its onset in children under six years of age, marked by dental discoloration, cavity formation, and eventual tooth destruction.² ECC, if left untreated, can lead to pain, infections, and premature loss of teeth, presenting various challenges that extend beyond oral health.³ Dental caries, including Early Childhood Caries (ECC), result from a multi-faceted interplay of various factors. At its core, dental caries is caused by specific bacteria in the oral cavity, such as Streptococcus mutans, which thrive on dietary sugars, particularly fermentable carbohydrates.⁴ These bacteria ferment sugars, producing acidic byproducts that, over time, demineralize susceptible tooth enamel. Repeated exposure to fermentable carbohydrates, especially between meals or before bedtime, heightens caries predisposition, as it culminates in frequent acid attacks on the teeth, limiting the opportunity for enamel recovery.⁴

In 2017, the incidence of oral health conditions was ranked third-highest among all health problems and consisted of 3.6 billion cases, and approximately 530 million children suffer from deciduous caries globally.⁵ ECC prevalence varies across countries and even within the same country.⁶ ECC has been studied across African countries, although only a few published studies exist in Nigeria, the largest indigenous black population.^7–19 According to available data, the prevalence of ECC in Nigeria varies across geopolitical zones: most studies were conducted in southern Nigeria, almost leaving out northern Nigeria.^13–37 This has negatively impacted the ability of stakeholders to generate national data on the condition. In Nigeria, dental caries is a leading childhood dental issue, accounting for the highest cause of poor oral health-related quality of life for children and caregivers, missed school hours, and economic losses for caregivers.¹³ To effectively prevent and manage ECC in Nigeria, it is essential to quantify the disease prevalence and spread within this population. The present study aims to determine the prevalence and distribution of ECC in Nigeria via a systematic review and meta-analysis.

The study adhered to the Preferred Reporting Item for Systematic Reviews and Meta-analyses (PRISMA) statement and checklist and was registered with PROSPERO in August 2023 with the number CRD42023451791.³⁸

2.1. Search strategy

Two authors (CCO and AOA) independently searched databases and registers for studies on the prevalence of Early childhood caries in Nigeria. The authors utilized relevant search terms and concepts to retrieve relevant information from the selected articles. The systematic search included PubMed, Scopus, EBSCOhost, and African Journal Online (AJOL). The authors also manually searched the dissertations from the National Postgraduate Medical College of Nigeria and the bibliography of previously selected articles. PubMed database was searched using Mesh Headings and keywords while Scopus, EBSCOhost, and AJOL were searched with keywords. The search concepts used in the search strategy included ("early childhood caries" OR "caries" "decay" OR "deft" OR "dental" OR "oral" OR " PUFA" OR " ICDAS") AND ("prevalence" OR “epidemiology” OR “distribution”) AND ("children" OR "perinatal" OR "pediatric" OR "pediatric" OR "neonatal" OR "infant") AND “Nigeria”.

2.2. Study selection

Utilizing the inclusion and exclusion criteria for the study, authors CCO and AOA searched through the titles, abstracts, and citations of retrieved studies following deduplication. The authors evaluated the eligibility of individual studies; studies without available full text were removed. This process was conducted independently by each of these two authors; in case of disagreement or discrepancies, a third author (COO) resolved this discrepancy.

2.3. Inclusion and exclusion criteria

The inclusion criteria for this study include all cross-sectional, case-control, cohort, and prevalence studies reporting the prevalence or epidemiology of early childhood caries (ECC) in Nigeria. Selected studies should be in English and available in full-text manuscripts. In cases where full-text articles are unavailable, the authors will send emails to the authors or the journal's editor. The authors will remove the article following a failure of response or communication. For articles quoted in multiple sources, the most comprehensive source will be selected. Exclusion criteria include dissertations, conference proceedings, review articles, commentaries/letters, and other grey literature.

2.4. Risk of bias assessment and quality of studies

Assessment of study bias and quality was evaluated using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Studies Reporting Prevalence Data. Two independent authors (COO and OA) utilized the checklist for selected studies, and discrepancies were resolved by a third author (AOA). The JBI checklist comprises nine questions for assessing the risk of bias with a Yes, No, Unclear, and “Not Applicable” likely response. The number of 'Yes' responses was summed up, and the risk of low, moderate, or high was given if the scores were above 70%, between 50–70%, and lower than 50%. Articles with less than 50% (high risk of bias) were excluded from data synthesis and downstream analysis of the prevalence of ECC in Nigeria.

2.5. Outcome measurement

The prevalence of ECC was the outcome measure for this systematic review and meta-analysis. The mean and standard deviation (or standard error) of the index used to measure the occurrence of caries is also an outcome measure. Lastly, the associated risk factors for caries in the studies were also outcomes of interest in the study. The prevalence of ECC was measured as the number of children under 72 months (6 years) that had caries divided by the total number of children under 72 months in the study population. The mean and standard deviation of the relevant index used in the study population were used to compute a pooled mean for ECC in Nigeria. In cases where the standard error was reported instead of the standard deviation, the standard deviation was derived as the multiplication of the standard error and the square root of the study population. Only DMFT/DMFT, PUFA, or ICDAS were utilized for the computation.

2.6. Subgroup and sensitivity analyses

Subgroup or moderator analyses were conducted across categories of groups to determine sources of potential heterogeneity. The subgroup utilized in the study included study designs, which were categorized into hospital-based, school-based, or community-based. Nigeria's cities where the studies were conducted were subdivided into geopolitical zones of Southwest, Southeast, South-south, Northwest, Northeast, and North-central zones. Studies were also divided into studies that included both children under 3 years (younger children) and children over 3 years (older children) and studies that only involved the older age group (over 3 years). These moderator analyses were conducted on the prevalence of ECC in Nigeria and the mean values of individual validated caries instruments. A meta-regression analysis of the prevalence of ECC with the year of publication and the study’s mean caries index was also conducted to investigate reasons for heterogeneity in the included studies.

To exclude influential and outlier studies in this meta-analysis, studentized residuals were calculated for each study, and studies with residuals ranging from − 3 to 3 were identified as outliers. A leave-one-out sensitivity analysis was also conducted to identify influential studies on the prevalence of ECC. Baujats plots and leave-one-out tables were used to visualize the outlier and influential studies and a bubble plot was used to visualize the computed meta-regression outcome.

2.7. Small study and publication bias

The influence of small studies and overall publication bias in the systematic review and meta-analysis was conducted visually using funnel plot symmetry and objectively using the rank correlation test, and Egger’s test. Where funnel asymmetry was detected following Egger’s test, the trim-fill method was utilized to correct for the asymmetry.

2.8. Data extraction

Following a review of selected studies, data extraction of relevant information from selected studies was inputted into Microsoft Excel version 16.86 (2024). Relevant information extracted included the surname of the first author, the year of publication, the city or town of the study, the geopolitical zone of the study site, the study design, the total number in the study population, the number of cases diagnosed as caries, the validated diagnostic index used for caries, the mean of the diagnostic index for ECC, the standard deviation (or standard error) if available, the gender distribution across cases if available and the proportion of severe ECC (S- ECC) if available. Authors (OA and YIA) extracted the relevant information from included studies.

2.9. Statistical analysis

Raw prevalence numbers were normalized by logarithmic transformation and utilized as the outcome measure. The normalized numbers were then pooled to calculate the overall prevalence of ECC in Nigeria using the DerSimonian-Laird random effects model. The pooled estimate was visualized through the forest plot. Along with Tau’s squared estimate, between-study heterogeneity was evaluated through the inconsistency index I2 (Higgins I2) and Cochran’s Q test for heterogeneity and their corresponding 95% confidence intervals. A pooled estimate of the mean index of caries diagnostic indices was also calculated after log transformation. The DerSimonian-Laird random effects model was also fitted to the model to determine the pooled mean of ECC in Nigeria from selected studies. All statistical analysis was conducted using the R programming language (version 4.3.3) (R Core Team, 2020) using the Meta, Metafor, and Dmetar packages.

3.0. Summary of studies

The search strategy through the databases, registers, and manual searches returned 1560 articles. Following deduplication, 869 articles were removed; 645 articles were further removed following a screening of titles, citations, and abstracts. A total of 46 articles were considered relevant for selection however, 14 studies were eliminated for not having a full-text manuscript. Of the remaining 32 studies for inclusion, 9 articles were excluded after full-text screening with reasons (secondary studies, cohort studies without relevant information on study sample and cases, review articles). PRISMA flowchart for selection of included studies is in Fig. 1.

3.1. Study Characteristics

The included studies were published between 1983 and 2023 and included studies from all the geopolitical zones of Nigeria except the North Central zone. There were 16 studies from the Southwest zone; Ile-Ife,^{15,20–21,29−32} Osun State, and Lagos State had seven studies each.^{17,19,22,25,33,35–36} The other two Southwest studies were from Ibadan.^16,23 The South-south,^26–27 Southeast,^18,28 and Northwestern^24,34 zones have two articles each, while the Northeast³⁷ has an article. The sample size of included studies ranged from 13 to 1549 participants; case counts ranged from 5 to 183 children.

Study locations were mostly school-based (11)^{16,18,25–28, 30, 33–35,37} followed by hospital-based studies (8);^{17,19,21–24,31,36} four included studies were conducted in the community or household setting.^15,20,27,32 All the studies utilized the decayed, missing, and filled teeth index (DMF) as the diagnostic index for caries. The studies of Folayan et al. in 2021²⁰ and Oziegbe et al.³⁰ in 2013 utilized the PUFA index alongside deft criteria. PUFA stands for Pulpal involvement (p), ulceration due to trauma from sharp tooth pieces (u), fistula (f) formation from a pulpal-involved tooth, and abscess (a) from a carious tooth.

The 23 articles in this systematic review and meta-analysis include Folayan et al. (2015),¹⁵ Iyun et al. (2014),¹⁶ Sowole et al. (2007),¹⁷ Onyejaka et al.(2016),¹⁸ Olatosi et al. (2015),¹⁹, Folayan et al. (2021),²⁰ Adekoya-Sofowora et al. (2006),²¹ Omotuyole et al.(2023),²² Popoola et al. (2013),²³ Oziegbe et al. (2013),²⁴ Sofola et al.(2013),²⁵ Eigbobo et al. (2017),²⁶ Alakija et al.²⁷ (1983), Onyejaka et al.(2021),²⁸ Folayan et al.(2019),²⁹ Oziegbe et al. (2023),³⁰ Folayan et al. (2008),³¹ Kolawole et al. (2016),³² Folayan et al. (2012),³³ Osuhor et al. (1983),³⁴ Adeniyi et al. (2016),³⁵ Oredugba et al. (2008),³⁶ and Ligali et al. (2023).³⁷ Table 1 shows the list of the articles and the data extracted from the studies.

Table 1

Summary of the main characteristics of the eligible studies.
Author	Year	Location	Zone	Total	Cases	Index	Mean_dmft	SD_dmft	Study_site
Folayan et al¹⁵	2015	Ife	SW	497	33	dmft	0.15	0.66	Community Based
Iyun et al¹⁶	2014	Ibadan	SW	540	127	dmft	0.65	1.49	School Based
Sowole et al¹⁷	2007	Lagos	SW	389	41	dmft	2.49	2.9	Hospital Based
Onyejaka et al¹⁸	2016	Enugu	SE	429	42	dmft	0.37	0.12	School Based
Olatosi et al¹⁹	2015	Lagos	SW	302	64	dmft	0.735	2.07	Hospital Based
Folayan et al²⁰	2021	Ife	SW	1549	73	dmft, PUFA, ICDAS	0.13	0.92	Community Based
Adekoya-Sofowora et al²¹	2006	Ife	SW	423	47	dmft	0.3		Hospital Based
Omotuyole et al. ²²	2023	Lagos	SW	30	5	dmft			Hospital Based
Popoola et al. ²³	2013	Ibadan	SW	39	19	dmft			Hospital Based
Oziegbe et al. ²⁴	2023	Kano	NW	346	11	dmft	0.08	0.5	Hospital Based
Sofola et al²⁵	2013	Lagos	SW	182	15	dmft	0.19	0.13	School Based
Eigbobo et al²⁶	2017	Port-Harcourt	SS	160	19	dmft	0.25	0.82	School Based
Alakija et al²⁷	1983	Benin	SS	83	10	dmft	1.97	0.03	School Based
Onyejaka et al²⁸	2021	Enugu	SE	48	9	dmft			School Based
Folayan et al²⁹	2019	Ife	SW	918	43	dmft			Community Based
Oziegbe et al. ³⁰	2013	Ife	SW	195	33	dmft, PUFA	0.58	0.14	School Based
Folayan et al³¹	2008	Ife	SW	106	42	dmft			Hospital Based
Kolawole et al³²	2016	Ife	SW	497	30	dmft			Community Based
Folayan et al³³	2012	Lagos	SW	104	15	dmft	0.34	1.31	School Based
Osuhor et al³⁴	1983	Zaria	NW	56	25	dmft	1.3		School Based
Adeniyi et al³⁵	2016	Lagos	SW	217	183	dmft	0.34	1.01	School Based
Oredugba et al³⁶	2008	Lagos	SW	13	5	dmft	1.46	2.06	Hospital Based
Ligali et al³⁷	2023	Maiduguri	NE	239	71	dmft	0.72	1.39	School Based

3.2. Risk of Bias Assessment for included studies.

Individual studies were critically appraised for risk of bias using the (Joanna Briggs Institute) JBI checklist for prevalence studies which comprised nine (9) questions with four likely potential responses. According to the JBI checklist, the studies ranged from low risk of bias (19 studies) to moderate risk of bias (4 studies). All studies were thus included in the meta-analysis for downstream computation of pooled estimate of prevalence and pooled mean dmft of ECC in Nigeria. Table 2 displays the JBI checklist for included studies.

Table 2

Assessment of included studies using the JBI criteria.
Studies	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	Q9	%Yes	Risk
Folayan et al. 2015¹⁵	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Iyun et al. 2014¹⁶	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	No	77.8	Low
Sowole et al. 2007¹⁷	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	88.9	Low
Onyejaka et al. 2016¹⁸	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	88.9	Low
Olatosi et al. 2015¹⁹	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	88.9	Low
Folayan et al. 2021²⁰	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Adekoya-Sofowora et al. 2006²¹	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	77.8	Low
Omotuyole et al. 2023²²	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	77.8	Low
Popoola et al. 2013²³	No	No	Yes	Yes	Yes	Yes	Yes	Yes	No	66.7	Moderate
Oziegbe et al. 2013²⁴	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Sofola. 2013²⁵	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Eigbobo et al. 2017²⁶	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Alakija et al. 1983²⁷	No	Yes	Yes	Yes	No	Yes	Yes	No	Yes	66.7	Moderate
Onyejaka et al. 2021²⁸	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Folayan et al. 2019²⁹	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Oziegbe et al. 2023³⁰	No	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	77.8	Low
Folayan et al. 2008³¹	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	77.8	Low
Kolawole et al. 2016³²	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Folayan et al. 2012³³	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Osuhor et al. 1983³⁴	No	Yes	No	No	Yes	Yes	Yes	Yes	Yes	66.7	Moderate
Adeniyi et al. 2016³⁵	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low
Oredugba et al. 2008³⁶	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes	66.7	Moderate
Ligali et al. 2023³⁷	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	100	Low

3.3. Prevalence of Early Childhood Caries in Nigeria

The 23 studies pooled a total of 962 cases from a study population of 7362 participants. Meta-analysis revealed the pooled estimated prevalence of ECC in Nigerian children from included studies is 17% (95% CI: 11–24, p < 0.001). Significant heterogeneity was observed between the studies with I2 = 97% (r2 = 1.2759) as shown in Fig. 2.Figure 2. Forest plot showing pooled prevalence estimate of Early Childhood Caries

3.3.1. Gender predilection

Of the included studies in this systematic review, only 7 articles reported gender distribution of affected ECC cases.^{15–19,21,30} The male prevalence proportion in these studies is 21.4% (Iyun et al.),¹⁶ 33.3% (Folayan et al.)¹⁵, 39.1% (Olatosi et al.)¹⁹, 65.9% (Sowole et al.)¹⁷, 54.8% (Onyejaka et al.),¹⁸ 50% (Adekoya-Sofowora et al.)²¹ and 18.2% (Oziegbe et al.)³⁰. The number of affected males from these studies is 111 and the affected female children are 126 with a male: female ratio of 1:1.14.

3.3.2. Age groups

Fifteen of the included studies reported prevalence for both the younger age group and the children over 3 years of age while the remaining studies only reported prevalence for children over 3 years. Of all included studies, information on age group delineation was only available in 7 studies with a pooled number of 198 children. Of the 198 children, 33 were children under the age of 3 years while the older age group (> 3 years) was 165 in a 1:5 prevalence ratio.

3.4. Subgroup (moderator) analysis

3.4.0. Year of publication

The heterogeneity of the year of publication was regressed against the prevalence of ECC in children in Nigeria. Meta-regression with year showed nil moderating effect of year of publication on the prevalence of ECC in Nigeria (p = 0.30).

3.4.1. Age groups

No moderating effect of age group of children on the prevalence of ECC following subgroup analysis with age group (p = 0.07). The pooled prevalence of studies on older children was however higher at 27% while the pooled prevalence for studies involving both groups was 12%. Age accounted for 12.1% of the study’s heterogeneity.

3.4.2. Geopolitical Zones

Moderator analysis with geopolitical zones showed a moderating effect of zones on the prevalence of ECC in Nigeria (p < 0.01). The pooled prevalence estimate reveals the North-east has the highest prevalence rate at 30% while the South-south has the lowest at 11%. This is shown in Fig. 3.

3.4.3. Study locations

The study settings or location had a moderating effect on the study’s heterogeneity (p = 0.01), accounting for 33.9% of the study’s heterogeneity. School-based study designs had the highest pooled prevalence rate of 22%; community-based population studies had a low prevalence rate of 5% (Fig. 4).

3.4.4. Mean Diagnostic Index of Early Childhood Caries.

The prevalence of ECC in Nigeria was also regressed against the mean diagnostic index in caries (dmft). The mean dmft had nil moderating effect on the study heterogeneity observed in this meta-analysis (p = 0.24)

Figure 5. Bubble plot showing prevalence of ECC against mean dmft scores

3.5. Sensitivity analysis and influential studies

Studentized residuals of included studies revealed the study of Adeniyi et al.³⁵ to be an outlier with its studentized residual (3.79). Random effects modelled sensitivity analysis also showed Adeniyi et al.³⁵ was an influential study. The Baujat plot and leave-one-out sensitivity analysis plot in Figs. 6a and b also showed this. Following the removal of the study of Adeniyi et al.³⁵, the recomputed pooled prevalence estimate of ECC in Nigeria was 14% (95% CI: 10–20) (Fig. 6b). The study heterogeneity also reduced from an I2 of 97% (95% CI: 96.7% − 97.8%, p < 0.0001) to an I2 of 95% (95% CI: 94.2% − 96.5%, p < 0.0001).

3.6. Publication Bias and Small Study Effect Bias

There was no evidence of publication bias in this meta-analysis and no obvious funnel plot symmetry (Fig. 7). In addition, Egger’s regression test (p = 0.696) and Peter’s regression test (0.126) also indicated nil significant publication bias. Egger’s regression test also showed no significant effect of small study effect bias (Table 3).

Figure 6a. Baujat plot showing the influential study in the prevalence of ECC.

Due to the absence of evidence for publication and small study effect bias, a trim and fill bias corrected method was not necessary.

Table 3

Egger’s Regression Test
Linear regression test of funnel plot asymmetry
Egger’s Test	Intercept	Confidence Interval	t	p
Egger’s Test	1.376	0-5.44–8.19	0.396	0.696
Bias estimate: 1.3762 (SE = 3.4776)

3.7. Mean DMFT of Early Childhood Caries in Nigeria.

Only 17 of the 23 included studies reported the mean dmft of ECC in their individual treatise. These 17 studies include a total number of 814 cases from 5724 total participants. The pooled mean dmft of ECC from the included studies is 0.44 (95% CI: 0.24–0.74). Similar to the pooled prevalence estimate, there is also significant heterogeneity with I² at 100% (r2 = 0.9617) (Fig. 8).

Subgroup analysis for the mean dmft across geopolitical zones and study settings revealed that both factors had a moderating effect on mean dmft scores (Fig. 9a and b). Northeast and South south zones had the highest mean dmft at 0.72 (95% CI: 0.56: 0.921) and 0.71 (95% CI:0.09: 5.39) respectively. Community-based studies had the lowest mean dmft at 0.14 (95% CI: 0.11–0.18) while school-based studies had the highest mean dmft at 0.48 (95% CI: 0.30–0.76)

Meta-regression across year of publication also revealed significant moderating effect of this factor on mean dmft of ECC (p = 0.0024) with year of publication accounting for 38.2% of the study variability on mean dmft. Age group of children, however, had no moderating effect on the mean dmft of ECC in this meta-analysis (p = 0.16).

Figure 9a: Forest plot showing subgroup analysis with geopolitical zones

Figure 9b: Forest plot showing subgroup analysis with study settings

3.8. Patient and public involvement statement

Neither patients nor the public was involved in the design, conduct, reporting, or dissemination of research plans.

This systematic review and meta-analysis provides the first comprehensive examination of Early Childhood Caries (ECC) prevalence and distribution in Nigeria. The findings reveal a pooled ECC estimate of 17% (95% CI: 11% – 24%), indicating that approximately one in six Nigerian children under six years of age experiences ECC. This prevalence places Nigeria at the lower end of both African and global estimates, ³⁹ which range from 10–60% and 12–70%, respectively. ^5–12 While this figure may seem relatively low, it nonetheless underscores a persistent challenge in addressing early childhood oral health in Nigeria.

The 17% prevalence rate in Nigeria is markedly lower than those reported in other African countries such as Namibia (31.69%)⁴⁰ and South Africa (44.94% and 51.72%).⁴¹ It also falls below rates observed in European, South American, and some Middle Eastern countries.^42–47 This trend aligns with the lower prevalence of dental caries in 12-year-old Nigerian children (13%) compared to other African nations, as reported by F. Kimmie-Dhansay et al.⁴⁸ The reasons for Nigeria's reduced prevalence remain unclear but may be attributed to socio-cultural factors and dental personnel availability. Interestingly, South Africa, despite having comparatively robust oral health care institutions, exhibits higher ECC prevalence rates.

The variability in ECC prevalence across studies likely reflects Nigeria's socioeconomic diversity. More affluent urban areas, such as Lagos, reported lower prevalence rates compared to less developed regions, highlighting the impact of poverty and inequality on oral health outcomes.⁶ This pattern contradicts findings from South Africa and Yemen, where lower prevalences were reported in poorer regions.^41,49 The discrepancy may be due to factors such as low dental awareness, limited dental workforce, and high sugar consumption in rural and northern areas of Nigeria.

The observed disparities underscore the need for targeted interventions to address ECC prevalence inequalities between urban and rural Nigeria. Creating an equitable oral health landscape requires investments in oral health education, promotion of healthy dietary habits, and advocacy for policies that reduce poverty and inequality. ⁶

The disparity across geopolitical zones may be partially attributed to the uneven distribution of studies, with only three from the Northern region compared to 14 from the Southern region. The Southwest zone, with the highest number of studies, exhibited varying prevalence rates, potentially influenced by intra-regional socioeconomic disparities. The limited data from the North, particularly the North Central region, emphasizes the need for further research. Additionally, cultural practices related to oral hygiene, dietary habits, and infant feeding may contribute to the observed differences, highlighting the importance of region-specific interventions.

ECC prevalence increased with age, with children over three years showing a fivefold higher risk of developing ECC. This age-related increase aligns with studies from South Africa and China.^41,50 The influence of age on dental caries occurrence involves dynamic changes during tooth development and maturation, in addition to the cumulative irreversible effects of the disease.^51,52 Gender predilection to caries remains inconclusive, with this review observing a slight female-to-male ratio. However, other studies have reported both male and female predilections, suggesting that factors beyond gender play a more significant role in ECC etiology.^53–58

While the dmft score has been the traditional mainstay for dental epidemiological research, its limitations in capturing early-stage caries are increasingly recognized. The International Caries Detection and Assessment System (ICDAS) offers a more sensitive and accurate measure of caries progression.⁵⁹ Consequently, the findings of this study should be interpreted cautiously due to the potential underestimation of caries prevalence. Moreover, the substantial heterogeneity among included studies underscores the need for further research to elucidate the complex factors influencing ECC in Nigeria.

Future research should prioritize important areas to comprehensively address the gaps observed in this systematic review and meta-analysis of ECC studies in Nigeria. First, it is important to conduct standardized, nationally representative surveys in order to gain a comprehensive understanding of ECC distribution across the country. Second, in-depth investigations into region-specific risk factors are necessary to tailor preventive interventions accordingly. Third, evaluating the efficacy of various preventive strategies within Nigeria will form the basis for the development of evidence-based programs. Finally, exploring the long-term consequences of ECC on children's development and academic achievement is essential to appreciate the disease's profound impact on overall child well-being.

This systematic review and meta-analysis provide information on the progress and persisting challenges with ECC in Nigeria. With a pooled prevalence of 17%, ECC remains a significant public health concern, demanding concerted efforts from policymakers, healthcare providers, and researchers. By addressing the socioeconomic determinants of oral health, improving access to dental care, and implementing evidence-based preventive strategies, Nigeria can work towards reducing the burden of ECC and improving the overall health and well-being of its youngest citizens.

Authorship contribution

Adetayo Aborisade: Writing − review & editing, Writing − original draft, Visualization, Validation, Methodology, Formal analysis, Data curation. Chizoba Okolo: Writing − review & editing, Data curation, Conceptualization. Chika Oguchi: Writing − original draft, Supervision, Software, Methodology, Investigation. Olusegun Alalade: Writing − original draft, Supervision, Resources, Methodology, Formal analysis. Yewande Adeyemo: Writing − review & editing, Supervision, Project admin- istration, Investigation.

Funding: This research did not receive funding from funding agencies in the public, commercial, or not-for-profit sectors

Data Availablity: The majority of data related to this review is available within this paper, and further information may be obtained from the corresponding author upon a reasonable request.

Competing interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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A Systematic Review and Meta-analysis on the Epidemiology of Early Childhood Caries in Nigeria

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Version 1

Abstract

Background

Methods

Results

Conclusion

Figures

Introduction

Materials and methods

2.1. Search strategy

2.2. Study selection

2.3. Inclusion and exclusion criteria

2.4. Risk of bias assessment and quality of studies

2.5. Outcome measurement

2.6. Subgroup and sensitivity analyses

2.7. Small study and publication bias

2.8. Data extraction

2.9. Statistical analysis

Result

3.1. Study Characteristics

3.2. Risk of Bias Assessment for included studies.

3.3. Prevalence of Early Childhood Caries in Nigeria

3.3.1. Gender predilection

3.3.2. Age groups

3.4. Subgroup (moderator) analysis

3.4.0. Year of publication

3.4.1. Age groups

3.4.2. Geopolitical Zones

3.4.3. Study locations

3.4.4. Mean Diagnostic Index of Early Childhood Caries.

3.5. Sensitivity analysis and influential studies

3.6. Publication Bias and Small Study Effect Bias

3.7. Mean DMFT of Early Childhood Caries in Nigeria.

3.8. Patient and public involvement statement

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

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