Evaluating the informational accuracy of large language models in patient‑directed orthodontic retainer guidance: a cross‑sectional comparison of Chat GPT‑4.1, Gemini 2.5, Microsoft Copilot GPT-4.1 and DeepSeek‑V3.

INTRODUCTION: The use of artificial intelligence (AI) in orthodontic practice is increasing rapidly; however, there is a notable lack of research evaluating the accuracy of large language models (LLMs) in educating patients about orthodontic retainers and related guidelines. MATERIALS AND METHODS: This study utilized a cross-sectional, repeated‑measures comparative evaluation design after receiving exemption from the institutional ethics committee. A set of 110 questions related to orthodontic retainers was compiled from previous articles addressing concerns about retainers and approved by a panel of three orthodontists. These questions were submitted to large language models (LLMs), including ChatGPT, Copilot, DeepSeek and Google Gemini. The responses were then reviewed by six independent orthodontists, who rated them using a modified five-point Likert scale. RESULTS: The overall accuracy revealed that 68.6% of responses scored 4, while 15.3% achieved a perfect score of 5. Among the LLMs, Gemini ranked first with 96.8%, closely followed by ChatGPT at 95.6%, indicating comparable high‑level performance between these models, while DeepSeek (76.9%) and Copilot (66.2%) demonstrated comparatively lower accuracy. Gemini produced a higher proportion of perfect scores, whereas ChatGPT consistently achieved strong ratings. The mean ratings across six raters demonstrated strong reliability (ICC = 0.81), reflecting expert agreement. CONCLUSIONS: Findings suggest that AI models such as ChatGPT and Gemini can generate patient‑directed orthodontic retainer information with high informational accuracy under controlled evaluation conditions. However, specialist oversight remains essential to ensure clinical applicability. Future research using larger and more diverse datasets is needed to assess broader educational and communication‑related outcomes.