<p>Assessment of risk of bias.</p>

Background

Oral hygiene is linked with dental caries experience. This systematic review and meta-analysis assessed the associations between oral hygiene status, the frequency of tooth brushing, and the prevalence of dental caries in Nigeria. It also examined how the geographical zones and dentition type moderate these associations, and identified the tools commonly used for oral hygiene maintenance.

Methods

The systematic review and meta-analysis was registered with PROSPERO (CRD42022367763). A search was conducted in PubMed, Web of Science, Scopus, African Journals Online, African Index Medicus, and Google Scholar in January 2026 for studies conducted between January 2001 and December 2025. Observational studies and clinical trials reporting baseline caries prevalence were included. There was no language restriction. Studies were excluded if they did not provide information on the sample size, had no study outcome data, featured duplicate samples, or were review articles, meta-analyses, case reports, case series, in vitro studies, commentaries/letters (editorials, opinion pieces) devoid of primary data. Pooled odds ratios (ORs) were estimated using random-effects models. Subgroup analyses were conducted by dentition type, geopolitical zone, study design, publication year, mean age, and sample size.

Results

Twenty-three cross-sectional studies were included, of which 20 (86.9%) were conducted in Southern Nigeria. Pooled data from 10 studies suggested poor oral hygiene was associated with 100% higher odds of dental caries (95% CI: 1.26–3.96; p = 0.003). After removing an influential outlier, the analysis showed a 76% increase in dental caries prevalence associated with poor oral hygiene (95% CI: 1.41–2.18; p = 0.003; I² = 0.00%). Brushing at least twice daily was associated with reduced dental caries (p < 0.001). Dentition type and publication year were significant moderators. The most common oral cleaning tool was a toothbrush with toothpaste, though chewing sticks, cotton wool, and other traditional tools were also reported.

Conclusion

Poor oral hygiene was linked to increased odds for dental caries, while twice-daily tooth brushing was protective in Nigeria. The type of cleaning tool was not significantly associated with dental caries risk, highlighting the importance of brushing frequency over tool type. Studies reporting on oral hygiene and dental caries in Northern Nigeria are needed to improve the national representativeness of the data.