Advertising of orthodontic appliances on websites in the UK: Do they comply with advertising standards? A cross-sectional study

Aim: To evaluate the compliance of websites promoting proprietary orthodontic appliances available in the UK against advertising standards outlined by the Advertising Standards Authority Committee of Advertising Practice (ASA CAP) Code. Design: Cross-sectional study. Setting: Websites promoting proprietary orthodontic appliances available in the UK, including fixed, removable and aligner systems sold as a complete system under a brand name. Methods: A comprehensive, systematic approach was adopted, beginning with a 2020 scoping search on Google and social media platforms (Instagram and Facebook) to identify keywords. Keyword searches were conducted on Google in 2020, 2023 and 2025 to identify relevant websites. To ensure contemporary relevance, only websites identified in the final 2025 search were included for analysis. Raters underwent training and calibration before independently evaluating websites for compliance with advertising standards using bespoke judgement criteria derived from the ASA CAP Code, across four domains: comprehensiveness of treatment information; presentation of treatment information; objectivity of treatment information; and substantiation of claims. Discrepancies were resolved through group discussion to determine agreed scores. Data were analysed using descriptive and inferential statistics (Fleiss’ kappa and Kruskal–Wallis tests). Results: The 2025 search identified 970 websites, of which 39 met the inclusion criteria. Inter-rater reliability showed almost perfect agreement (kappa >0.9). Compliance varied significantly across domains: 45% of all claims provided comprehensive information, 54% had clear presentation, 38% maintained objectivity and only 4% of claims were substantiated with evidence. Nearly all websites (95%) omitted common risks and 92% failed to mention alternative treatments. Direct-to-consumer and tele-dentistry websites showed poorer compliance than dentist-delivered systems. Conclusions: Orthodontic appliance websites showed poor compliance with ASA CAP Code standards. The majority used descriptive language and words in place of numbers to quantify magnitude, alongside subjective content and unsubstantiated claims, with omissions of treatment risks. These findings raise significant concerns about online orthodontic advertising and its potential impact on informed patient decision-making.