Development and psychometric validation of the Orthodontic Health Literacy (OrthoHL) scale for the general population

To develop and evaluate the reliability and validity of the Orthodontic Health Literacy (OrthoHL) Scale, designed to measure orthodontic health literacy. The scale was developed following a four-phase process that included item development, factor analysis, reliability assessment, and validity assessment. Data were collected in Wuhan, China, from three participant groups (total n = 974; n = 412, 512, and 50) in 2024. Item development phase utilised the Delphi method, achieving expert consensus from 13 specialists across orthodontics, general dentistry, nursing and public health and human factor engineering/ergonomics. Reliability assessment was conducted through internal consistency and test-retest methods, and validity assessment used exploratory factor analysis and confirmatory factor analysis. The 19-item OrthoHL Scale demonstrated strong psychometric properties, including acceptable test-retest reliability, internal consistency, and content, convergent, discriminant, and criterion-related validity. Additionally, the OrthoHL Scale had four dimensions of orthodontic health literacy, namely orthodontic knowledge, information access, information evaluation and specialist selection. The four dimensions were positively correlated with proactive orthodontic behaviours. The OrthoHL Scale is a reliable and valid tool for evaluating the orthodontic health literacy and facilitates dental health studies that take orthodontic health literacy into account.