Detecting white spot lesions on post-orthodontic oral photographs using deep learning based on the YOLOv5x algorithm: a pilot study

Abstract

Background: Deep learning model trained on a large image dataset, can be used to detect and discriminate targets with similar but not identical appearances. The aim of this study is to evaluate the post-training performance of the CNN-based YOLOv5x algorithm in the detection of white spot lesions in post-orthodontic oral photographs using the limited data available and to make a preliminary study for fully automated models that can be clinically integrated in the future.

Methods: A total of 435 images in JPG format were uploaded into the CranioCatch labeling software and labeled white spot lesions. The labeled images were resized to 640 × 320 while maintaining their aspect ratio before model training. The labeled images were randomly divided into three groups (Training:349 images (1589 labels), Validation:43 images (181 labels), Test:43 images (215 labels)). YOLOv5x algorithm was used to perform deep learning. The segmentation performance of the tested model was visualized and analyzed using ROC analysis and a confusion matrix. True Positive (TP), False Positive (FP), and False Negative (FN) values were determined.

Results: Among the test group images, there were 133 TPs, 36 FPs, and 82 FNs. The model's performance metrics include precision, recall, and F1 score values of detecting white spot lesions were 0.786, 0.618, and 0.692. The AUC value obtained from the ROC analysis was 0.712. The mAP value obtained from the Precision-Recall curve graph was 0.425.

Conclusions: The model's accuracy and sensitivity in detecting white spot lesions remained lower than expected for practical application, but is a promising and acceptable detection rate compared to previous study. The current study provides a preliminary insight to further improved by increasing the dataset for training, and applying modifications to the deep learning algorithm.

Clinical revelance: Deep learning systems can help clinicians to distinguish white spot lesions that may be missed during visual inspection.

Keywords: Artificial intelligence; Deep learning; Dentistry; Photography; White spot lesions.

Fig. 1

Diagram of the white spot lesions segmentation model development steps

Fig. 2

Correlogram showing YOLOv5x performance

Fig. 3

White spot lesions segmentation on intraoral photograph using the AI model. The graphs of the ROC analysis results for white spot lesions segmentation

Fig. 4

Confusion matrix showing the YOLOv5x segmentation performance for the test sample

Fig. 5

The graphs of the ROC analysis results for white spot lesions segmentation

Fig. 6

a. Precision-Confidence Curve. b. Recall-Confidence Curve. c. F1- Confidence Curve. d. Precision-Recall Curve