Factors Influencing Decisions to Obtain Fashion Orthodontics From Nondental Providers Among Young Adults in Mueang Phayao District, Thailand

Background: Fashion orthodontics, imitation appliances placed by unlicensed providers, has emerged as a significant public health concern among Thai youth. Despite documented risks, including tooth decay and heavy metal toxicity, the psychosocial drivers behind this trend remain under-researched in provincial settings. Objectives: To identify the psychosocial and structural factors influencing the intention and adoption of fashion orthodontics among young adults (18-25 years) in Mueang Phayao district, Thailand, by integrating the health belief model and the theory of planned behavior. Methods: An explanatory sequential mixed-methods design was employed. In Phase 1, focus group discussions (n = 34) and in-depth interviews (n = 12) were conducted to explore motivations and perceived risks. These findings informed the development of a Phase 2 quantitative survey (N = 400). Participants were recruited using multistage cluster sampling. Data were analyzed using multivariate logistic regression, ordinal regression with Brant test verification, and structural equation modeling. Results: The prevalence of ever or current orthodontics use was 19.8%, with 22.0% reporting high intention within the past 12-months. Subjective norms (peer influence) were the strongest predictors of both behavior (adjusted odds ratio [aOR], 1.46; 95% CI, 1.26-1.69) and intention (proportional OR [pOR], 1.52; 95% CI, 1.33-1.74). Favorable attitudes and high perceived behavioral control significantly increased uptake, whereas higher oral health literacy and perceived risk acted as protective factors. Structural barriers to standard care, such as long waiting times (median 28 days), further encouraged young adults toward unregulated alternatives. Conclusions: Adoption is primarily driven by social norms and aesthetic desires rather than medical necessity. Interventions should focus on behaviorally informed risk communication and improving access to licensed orthodontic services to protect young adults’ oral health.