Tooth brushing practice in Ethiopia: a systematic review and meta-analysis

Oral hygiene refers to taking care and maintaining the cleanness of gum and teeth; a good oral hygiene practice promotes better oral health in general. Oral hygiene is the top public health concern of the population. Tooth brushing is a technique to keep oral hygiene from related complications. Therefore, this study provides the pooled prevalence of tooth brushing practice in Ethiopia. Databases searched for articles systematically across PubMed, Google Scholar, Hinari, EMBASE, and African Journals Online. Two reviewers independently conducted the selection, screening, reviewing, and data extraction using a Microsoft Excel spreadsheet and used the Joanna Briggs Institute prevalence critical appraisal tools to assess the quality of evidence. All studies conducted in Ethiopia from 2010 to 2020, reporting tooth-brushing practices extracted for and imported into the Comprehensive meta-analysis version 3.0 for further analysis. Beggs and Eggers’s tests evaluated for publication bias with Higgins’s method evaluated for heterogeneity. A random-effects meta-analysis model with a 95% confidence interval was computed to estimate the pooled effect size (prevalence). Furthermore, the authors employed subgroup analysis based on the study area and sample size. After reviewing 36, 10 articles fulfilled the inclusion criteria, and were included in the meta-analysis. The pooled prevalence of tooth brushing practice was 12.2% (95% CI 7.6–19.2%). The review reported a lower level of tooth-brushing practice in Ethiopia. We recommended that special attention should be given to the oral hygiene of the Ethiopian people.

www.nature.com/scientificreports/ structural, aesthetic, physiologic, and psychosocial state of well-being that is essential to an individual's general health and quality of life" 24 . Oral hygiene is the top public health concern of the world population 25 same talk; the prevalence of oral diseases in Ethiopia was observed at up to 90% of the population 26 . Corpus of evidence reported the positive effect of tooth brushing at preventing and reducing the oral health conditions [27][28][29][30][31][32] .
To the best of the researcher's knowledge, the level of tooth brushing practice in Ethiopia was not a well investigated and understood area; and hence this review examined the state of evidence on the level of toothbrushing practice in Ethiopia. The review question is "What is the level of tooth brushing practice in Ethiopia?".

Methods
Reporting. The preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline 33 was used to report this meta-analysis (Additional File 1 research checklist).
Searching strategies. The reviewers followed the PRISMA systematic review protocol as a reporting guideline for the PRISMA checklist, eligible studies for the study were selected in terms of titles, abstracts, and then full articles based on inclusion criteria. PubMed, EMBASE, Hinari, African Journals Online, and Google scholar systematically searched for based on controlled and free-text languages. In terms of free-text searches, the keywords included the followings: (Tooth Brushing OR Dental Problems OR Dental Caries) AND Ethiopia. The controlled searches included the following Medical Subject Heading (MeSH) terms: "tooth brushing", and "Ethiopia" as recommended for each database. The search terms were used individually and in combination using "AND" and "OR" Boolean operators. Moreover, the search was guided by PICO, population-a population that practiced tooth brushing.
Inclusion and exclusion criteria. The reviewers included the following type of studies (1) study population comprised any age group, (2) study outcome is tooth brushing, (3) study design is cross-sectional, and articles published in English language. Meanwhile, the reviewers excluded the following, (1) qualitative studies, (2) report language is non-English, and (3) year of publication is older than 2010.
Outcome of interest. PICO. The population of the study was any age group that brushed tooth. The main outcome was the tooth brushing practice reported in the reviewed articles both as percentage and frequency, calculated by dividing the number of individuals who brushed their tooth twice or more times a day by the total sample size then multiplied by 100.
Screening and data extraction. Two reviewers (SAT and WMT) screened titles and abstracts against the inclusion criteria and then did an independent assessment for full text articles based on the predetermined inclusion and exclusion criteria. Arguments discussed and reached on complete consensus. The three authors (SAT, WMT, and FEM) independently did the data extraction from a random sample of 20% to check consistency and found no variation.
Study quality assessment. While designing a data abstraction form on Microsoft Excel, the reviewers emphasized for clarity of the data, objective, study design, population, year of publication, sample size, and proportion of tooth brushing (Table 1). An assessment for the methodological qualities was based on the Joanna Briggs Institute prevalence critical appraisal tool for the critical appraisal of the studies 34 .
Data synthesis and statistical analysis. The extracted data using Microsoft Excel spreadsheet imported to Comprehensive meta-analysis version 3.0 software for further analysis. The pooled effect size with a 95% confidence interval of tooth brushing practice was determined using a weighted inverse variance random-effects model. The I 2 statistic used for assessing the heterogeneity across the studies, where 25, 50 and 75% represent low, moderate, and high heterogeneities consecutively 46 . A funnel plot and Beggs and Eggers tests evaluated the risks of publication bias 47 .

Results
Selection of the studies. A comprehensive literature search for the databases yielded 36 published articles, of which eight articles retrieved from PubMed, 13 articles from EMBASE, African journals online, and Hinari, and 15 articles from Google Scholar. Twenty-one articles excluded once assessed for duplication. Fifteen articles screened by abstracts, of which five articles excluded for no outcome report. Ten full-text articles that fulfilled the eligibility criteria with a total sample size of 3156 included in the final analysis for the systematic review and meta-analysis (Fig. 1).

Characteristics of the included studies.
Pertinent information about authors, publication year, population, study area, sample size, age groups, outcome, and main findings from the selected articles were extracted and presented in Table 1. All articles were cross-sectional and in Ethiopia from 2010 to 2020 and published in indexed journals. The studies were conducted in Jimma 38 www.nature.com/scientificreports/ Tooth brushing practice. In this systematic review and meta-analysis, the pooled estimate of tooth brushing practice was described by forest plot. The pooled prevalence of tooth brushing practice in Ethiopia from the random effects method observed was 12.2% (95% CI 7.6-19.2%) (Fig. 2).
Assessment of publication bias. The funnel plot found to be asymmetry and Begg's and Egger's tests showed presence of a significant publication bias at a P-value of 0.05 (Fig. 3).

Investigation of heterogeneity.
For identifying the possible causes of variation across the studies, metaregression analysis was done using sample size and study area. The result showed that there is no significant heterogeneity across the studies (P > 0.05) ( Table 2).

Discussion
This systematic review and meta-analysis aimed at providing comprehensive evidence on the level of tooth brushing practice in Ethiopia from 2010 to 2020. The finding from this study reported an overall level of tooth brushing practice of 12.2%. Thus, this was consistent with the findings of 14.5% in Nigeria 50 and 15.9% in Sudan 51 . The current review reported a much lower level of tooth brushing practice than studies across different parts of the world. For instance, a higher level of tooth brushing practice was reported at 77.5% in Kenya 52 , 76.6% in Malawi 53 , 72.4% in Tanzania 54 , 56.5% in Uganda 55 and 57% in Iran 56 . This variation might be due to variations in scope of the studies and sample size.
Understanding all the variations in the scope and level of emphasis to the assessment of oral hygiene, there exists differences in the level of tooth brushing practice. As an evidence for this is; reports from China and Italy reported a tooth brushing practice of 44.4% 57 and 33.6% 58 respectively. Where such variation might be due to differences in population characteristics across the studies.
There exists a variation in the distribution of level of oral hygiene (tooth brushing) across the global population. This uneven distribution to happen to the people might take on difference factors that includes service access differences, awareness level, perception, and healthcare infrastructure. A report from India revealed a level of tooth brushing practice of 99.5% 59 , which is by far higher than the current review report.
With a relative understanding, studies from Eritrea and Sudan reported a tooth brushing practice of 19.1% 60 and 20% 28 respectively which is almost comparable with the current review report.
Moreover, an assessment from Saudi Arabia reported the tooth brushing practice of 41.5% 61 . A study from Jorpati, Kathmandu, Nepal also reported the tooth brushing practice of 36.9% 62 . Comparing these findings with the current review report, it is clear that a higher level of oral hygiene practice. A finding from Nigeria also reported a higher level tooth brushing practice which was 28.46% 63 . This variation might be due to differences in scope across the studies.    Limitation of the systematic review and meta-analysis. In the current study, tooth brushing was measured two or more times of tooth brushing per day. However, the authors didn't get a comprehensive expression within the reviewed articles. The authors acknowledge shoratge of related lietertaure while discussing the finding.

Conclusion
The review reported a lower level of tooth brushing practice in Ethiopia. Strengthening tooth brushing practice in Ethiopia is a key to the promotion of oral hygiene and therefore; concerned bodies Should work on the identified oral health concern of the Ethiopian population.

Data availability
The data that supported the finding of this study are available within the manuscript and supplementary file.