Diagnosis and prediction of periodontally compromised teeth using a deep learning-based convolutional neural network algorithm

Abstract

Purpose: The aim of the current study was to develop a computer-assisted detection system based on a deep convolutional neural network (CNN) algorithm and to evaluate the potential usefulness and accuracy of this system for the diagnosis and prediction of periodontally compromised teeth (PCT).

Methods: Combining pretrained deep CNN architecture and a self-trained network, periapical radiographic images were used to determine the optimal CNN algorithm and weights. The diagnostic and predictive accuracy, sensitivity, specificity, positive predictive value, negative predictive value, receiver operating characteristic (ROC) curve, area under the ROC curve, confusion matrix, and 95% confidence intervals (CIs) were calculated using our deep CNN algorithm, based on a Keras framework in Python.

Results: The periapical radiographic dataset was split into training (n=1,044), validation (n=348), and test (n=348) datasets. With the deep learning algorithm, the diagnostic accuracy for PCT was 81.0% for premolars and 76.7% for molars. Using 64 premolars and 64 molars that were clinically diagnosed as severe PCT, the accuracy of predicting extraction was 82.8% (95% CI, 70.1%-91.2%) for premolars and 73.4% (95% CI, 59.9%-84.0%) for molars.

Conclusions: We demonstrated that the deep CNN algorithm was useful for assessing the diagnosis and predictability of PCT. Therefore, with further optimization of the PCT dataset and improvements in the algorithm, a computer-aided detection system can be expected to become an effective and efficient method of diagnosing and predicting PCT.

Keywords: Artificial intelligence; Machine learning; Periodontal diseases; Supervised machine learning.

Figure 1. Overall architecture of the deep CNN model. The dataset for the PCT images (224×224 pixels) is labeled as the input. Each of the convolutional layers is followed by a ReLU activation function, dropout, maximum pooling layers, and 3 fully connected layers with 1,024, 1,024, and 512 nodes, respectively. The final output layer performs 3 classifications using the Softmax function.

CNN: convolutional neural network, PCT: periodontally compromised tooth, ReLU: rectified linear unit.

Figure 2. Multiclass classification confusion matrix with and without normalization using a deep CNN classifier. The diagonal elements are the number of points where the predicted label was the same as the actual label, while the non-diagonal elements were misinterpreted by the classifier. The higher the diagonal value and the darker the shade of blue, the more accurate the diagnosis of health and periodontally compromised teeth (A, B) Premolars without/with normalization. (C, D) Molars without/with normalization.

CNN: convolutional neural network.