A Multimodal Model for Caries Screening Using Intraoral Images and Questionnaires

To develop a multimodal deep learning model for dental caries screening in children by integrating intraoral photographs and questionnaire-based data, and to compare its performance against that of a unimodal model utilising images alone.

In total, 7671 images (3913 occlusal and 3758 smooth surfaces) were collected from children across different dentition stages. Oral health questionnaires were also conducted. The images were clinically labelled into three categories: caries-free, early caries, and moderate-to-severe caries. A multimodal model integrating intraoral images and questionnaire data was trained and evaluated against an image-only unimodal model. The performance metrics included accuracy, precision, recall, F1 score, and the area under the receiver operating characteristic curve (ROC-AUC). SHapley Additive exPlanations (SHAP) analysis was conducted to interpret feature importance.

For the multimodal model, occlusal surface classification achieved an accuracy of 92.3% for the caries-free category, 89.2% for the early caries category, and 93.7% for the moderate-to-severe caries category, with ROC-AUCs of 0.967, 0.911, and 0.972, respectively. The performance of smooth surfaces was similarly strong (an accuracy of 92.1% for the caries-free category, 96.7% for the early caries category, and 93.4% for the moderate-to-severe caries category), with ROC-AUCs of 0.938, 0.908, and 0.963, respectively. Incorporating questionnaire data improved recall for the early caries category without compromising overall accuracy. SHAP analysis provided interpretable insights into model decision-making.

Compared with the image-only unimodal model, the multimodal deep learning model increased early caries recall while preserving overall diagnostic performance.

This study describes a multimodal caries intelligent screening model, demonstrating its potential as a population-level screening tool. However, further large-scale, multicentre validation is necessary to confirm its generalisability and effectiveness.