We report this manuscript in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA statement) guideline [23] (Supplementary material 1).
Search strategy
A systematic library search was conducted by one of the authors (ASM) in consultation with a librarian across five electronic databases (CINAHL, Embase, PsycINFO, PubMed, and Scopus). Grey literature was searched from ProQuest Dissertations and Theses. The key words used in the search included; Oral, dental, Health, Literacy, tool, instrument, questionnaire, Psychometric, validity, reliability. Only peer-reviewed articles that were written in English were considered. The full search strategy for each database is provided in Supplementary material 2. A hand-search of relevant bibliographies was performed to identify potential studies that were excluded.
Studies that fulfilled the following criteria were included: (1) assessed one or more of the following psychometric properties: internal consistency, reliability, measurement error, content validity, face validity, structural validity, hypothesis testing, cross-cultural validity, criterion validity, or responsiveness; (2) all studies published between each database's inception and January 2019 that have been design, develop, or psychometric to measure oral and dental health literacy; and (3) studies published in English language. Studies were excluded if they were (1) conference abstracts, systematic review and meta-analysis, and other studies that did not meet the inclusion criteria as well (2) psychometric property testing protocols.
Screening, Data extraction
Search strategies were performed by two trained authors (ASM and SR). The authors were the same at all stages of the study. In the first stage, titles and abstract of the articles were evaluated. In the second stage, the full text of the articles was independently reviewed by two authors. Differences in judgment were resolved through a consensus procedure. In this study, the End Note software was used to organize the references. Data extraction included author, year, target population, sample size, location of the study, complete instrument name, report, time management (min), number of questions and scales, and rating. One part of the data extraction is related to the process of qualitative evaluation of the tools which is discussed below. The searches conducted From February to April 12. The authors entered the data existed in the articles into Excel software based on the items in the data extraction section.
The process of qualitative evaluation of the tools entered into the study
We used two important factors to test the tools used in the study:
1) An overall assessment of a tool (using the skills introduced by Sørensen et al) in analyzing the content of studies in terms of the definitions of oral and dental health literacy. This process evaluates the tools based on different dimensions, including the reading dimension (basic skills for reading based on the International Student Assessment [PISA]), interactive dimension (the ability to communicate about health issues), perceptual dimension (the ability to extract meaning from information sources), and computational dimension (the ability to perform numeric tasks and mathematic operations). The remaining dimensions includes; information search (which requires the ability to find information on health for health management), performance (the ability to use and process, or act upon health information and informed decision), assessment (ability to filter, change and evaluate information), and responsibility (the ability to take responsibility and make decision on health and Health care), [22].
2) Qualitative assessment of methodology and psychometric properties. To evaluate the psychometric section, the COSMIN checklist (the consensus-based standards for the selection of health measurement instruments) was used [24]. This tool examines the quality of studies in 4 areas, 12 domains and 114 items. The 12 domains include; internal consistency, reliability, measurement error, content validity, structural validity, hypothesis testing, cross-cultural validity, criterion validity, responsiveness of theory methods (if applied), interpretability, and generalizability of the tool’s properties.
All 114 items were evaluated according to the poor, fair, good, and excellent scale[25, 26]. Since there is no gold standard for the oral and dental health literacy tools[27], the domain of Criterion validity was not considered.