PaXNet: Tooth segmentation and dental caries detection in panoramic X-ray using ensemble transfer learning and capsule classifier

Arman Haghanifar, Mahdiyar Molahasani Majdabadi, Sina Haghanifar, Younhee Choi, Seok-Bum Ko

Abstract: Dental caries is one of the most chronic diseases involving the majority of the population during their lifetime. Caries lesions are typically diagnosed by general dentists relying only on their visual inspection using dental x-rays. In many cases, dental caries is hard to identify in x-rays and can be misinterpreted as shadows due to the low image quality. In this research study, we propose an automatic diagnosis system to detect dental caries in Panoramic images, which benefits from various deep pretrained models through transfer learning to extract relevant features and uses a capsule network to draw prediction results. Using a dataset of 470 Panoramic images, our model achieved an accuracy of 86.05% on the test set. The obtained score demonstrates acceptable detection performance and an increase in caries detection speed, as long as the challenges of using Panoramic x-rays are taken into account. Among carious samples, our model acquired recall scores of 69.44% and 90.52% for mild and severe ones, confirming the fact that severe caries spots are more straightforward to detect and efficient mild caries detection needs a larger dataset. Considering the novelty of current study as using Panoramic images, following work is a step towards developing a fully automated system to assist domain experts.