Evaluation of LLMs for Automated Dental-to-Medical Consult Letter Generation: Comparative Study

INTRODUCTION AND AIMS: For dental patients with systemic diseases, multidisciplinary care via referral letters is essential for clinical safety. This study evaluated the clinical feasibility and quality of dental-to-medical referral letters generated by Large Language Models (LLMs). METHODS: Using 153 paired datasets, three LLMs - Gemini-2.5-Pro, GPT-5 and MedGemma - generated referral letters via a standardised prompting framework. Two dental clinicians performed a blinded assessment across nine sub-criteria covering content, style and correctness. GPT-5 also performed an automated evaluation. Statistical significance was analysed using Friedman and Wilcoxon signed-rank tests with Holm correction. RESULTS: In the human clinical evaluation, Gemini-2.5-Pro achieved the highest overall performance (TOTAL mean SCORE: 2.9487 with a bootstrap 95% confidence interval [CI] of 2.9345-2.9606), significantly outperforming GPT-5 (2.8818 with 95% CI of 2.8613-2.9008) and MedGemma (2.8613 with 95% CI of 2.8338-2.8865) (P < .05). While GPT-5 showed high clarity in systemic problem descriptions, MedGemma excelled in structural adherence. The overall performance difference between GPT-5 and MedGemma was not statistically significant (P = .3519). Inter-rater reliability was strong in the prompt search dataset (QWK: 0.7175) but lower in the independent test dataset (QWK: 0.1505), reflecting the subjective nature of clinical document assessment; therefore, final human scores were reported as average ratings from two blinded clinicians with bootstrap confidence intervals. Notably, GPT-5's self-evaluation results deviated from human judgment, exhibiting potential model-based bias. CONCLUSION: This preliminary study suggests the potential of Gemini-2.5-Pro for automated consult letter generation, though the low test-set inter-rater reliability (QWK: 0.1505) highlights the subjective complexity of clinical text. To integrate these assistive prototypes into routine clinical application, more systematic studies are required. CLINICAL RELEVANCE: Integrating LLMs offers a promising approach to assisting with dental-to-medical referrals, presenting a potential future benefit of reducing administrative workloads and enabling healthcare providers to focus on safe, empathetic patient care.