1. Protocol development
This protocol draws on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) guidelines (25). A completed PRISMA-P checklist for the protocol is attached as an additional file (Additional file). The review subject has been submitted in the International Prospective Register of Systematic Reviews (PROSPERO) database (26). all updates and amendments will be tracked in PROSPERO.
2. Ethics and Dissemination
Because the data will be retrieved from previously published studies, ethical approval is not required. The results of this study will be widely disseminated through publication in a peer-reviewed journal. Any modifications to the protocol will be stated in the systematic review article.
3. Data sources and search strategy.
Search strategies will be performed on electronic databases: ISI, Scopus, and PubMed. Study selection and data collection will be performed independently by two reviewers. Search concepts include toothbrush age, toothbrush worn, and toothbrush replacement. Systematic searches will be conducted by applying every possible combination of keywords related to these concepts. Oral health index key terms will not limit the searches to reach as many as possible articles. All the reference lists of the included studies will be checked to identify the potentially eligible studies. The search strategy has been shown in Table.
Table 1
Search terms used in literature search in PubMed
Searching strategy
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(("old toothbrush"[Title/Abstract] OR "new toothbrush") [Title/Abstract] OR (wear [Title/Abstract] OR worn) [Title/Abstract] OR “tooth brush renewal” [Title/Abstract] OR “tooth brush replacement” [Title/Abstract] AND “toothbrush” [Title/Abstract]
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4. Eligibility criteria
4-1. Types of studies:
The Clinical trial and observational studies in humans will be included in this study.
4-2. Participants:
There was no restriction concerning the characteristics of the study population,
4-3. Intervention/exposure:
Studies that investigated the effectiveness of manual toothbrush longevity in the natural toothbrush-worn model will be included. We will not apply any restrictions on the duration of the toothbrush utilization.
4-4. phenomena of interest:
Studies that assessed each clinical objective Oral health indices such as gingival index, plaque index, periodontal index and etc, will be included.
Publication language:
We will consider only publications in the English language.
Time and location:
No restrictions will be applied concerning the time and location of the publication.
Table 2
Study inclusion and exclusion criteria
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Inclusion criteria
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Exclusion criteria
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Study design
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Clinical trial and observational studies
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All other types of study
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Participants
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humans
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None
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Intervention/exposure
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manual toothbrush longevity in the natural toothbrush-worn model
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an artificially worn toothbrush model
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Intervention/exposure period
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No limitations
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None
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phenomena of interest
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any types of objective oral health indices (Quigley Hein plaque index (QHI), papilla bleeding index (PBI), and gingival index (GI), ...)
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1. Subjective evaluation of toothbrush efficacy
2. Non-clinical indices like laboratory determined wear of toothbrush
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Publication language
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Full articles in English
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papers in non-English languages
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Study Time
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No limitations
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None
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setting
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No limitations
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None
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5. Data extraction and quality assessment
5-1. Selection of studies.
All the potentially eligible studies will be imported into EndNote X20 literature management software (Thomson Reuters [Scientific] LLC, Philadelphia, PA). Then Duplicates of individual studies will be deleted. Two reviewers will Screen all the records based on title and abstract against the eligibility criteria independently. Following this, selected papers’ full-text will be studied to find final eligible studies by two reviewers. Different opinions will be resolved through discussion or by a third author. The selection process will be summarized according to the PRISMA flow diagram.
5-2. Data extraction and management.
two reviewers will independently extract data from each study using a piloted data extraction form. If necessary, the forms shall be continually modified until the final data extraction form is complete. If clarification on details of included studies is needed, the study authors will be contacted for more information.
The following items will be extracted:
5-2-1. Study information:
author, year of publication, the country where the study was performed.
5-2-2. Participant characteristics:
Total number, age, sex, sociodemographic details.
5.2.3. Descriptive information about variables:
Exposure related variables:
Toothbrush utilization period will be extracted as an essential variable. Then other comorbid conditions and interventions will be extracted such as the measure of bristle splaying (wear index), the brand of toothbrush, the force of brushing, method of brushing, frequency and duration of brushing, use of oral health aids such as mouthwash and type of toothpaste, and other conditions may affect the outcomes.
Outcomes related variables:
Any objective Oral health index such as gingival index, plaque index, periodontal index, etc.
1. Assessment of risk of bias
We will assess all clinical trial studies included in the review for risk of bias independently by using Cochrane Risk of Bias Tool 2 (27). For observational studies, we will follow the Newcastle-Ottawa Quality Assessment Scale (28). Studies will be categorized as being at low, high, or unclear risk of bias.
6. Management of missing data.
We shall contact the corresponding author via email to deal with relevant missing data in included studies. If the data are still not available, we will perform data synthesis through existing information and address the potential impact of missing data in the Discussion section or impute missing standard deviations.
6-1. Quality of evidence.
The results of the main outcomes will be summarized in the findings tables. To assess the quality and strength of evidence, we will follow The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach (29). Levels of evidence quality will be classified into four groups: high, moderate, low, or very low.
7. Data synthesis
The findings and conclusions from the included studies will be presented in narrative form, including tables and figures to aid in data presentation. We will provide summaries of the intervention effects for each study by calculating dichotomous data by using odds ratio (OR) with 95% confidence interval (CI) and continuous outcomes using weighted mean differences (with 95% CI) or standardized mean differences (95% CI). We will conduct meta-analyses if enough homogeneity between studies will found. Studies that are unadjusted for potential confounders for our data synthesis will include sensitivity analyses.
7-1. Assessment of heterogeneity
To evaluate statistical heterogeneity in effects between included studies, we will use Cochran’s Q test and I-squared statistic as the magnitude of heterogeneity variance parameter (30). In case of high unexplained heterogeneity (P <.05 for Q test or I2 >50% for I2), we will explore sources of heterogeneity by subgroup analysis. If no heterogeneity was identified (P >.05 for Q test or I2 <50% for I2 test), the Mantel–Haenszel fixed effect model will be employed.
7-2. Subgroup analysis.
we are going to conduct subgroup analyses if meta-analyses have high heterogeneity by using the following variables:
children versus adult
professional method of brushing versus self-performed.
7-3. Sensitivity analysis.
Sensitivity analysis will be conducted to assess the robustness of the study conclusion and the impact of methodological quality, sample size, analysis methods, type of outcomes, intervention variations, and various statistical aspects on the meta-analytical results. The influence of the individual dataset on the pooled ORs will be assess. The results will not be substantially changed when any study is excluded if the pooled ORs are robust.
7-4. Publication bias.
If more than ten studies with the same outcome measure are available for review, a funnel plot (a plot of effect estimates against sample sizes) will be used to explore the potential of publication bias.