PRAD++: Toward Robust Periapical Radiograph Analysis Through Dataset and Model Advancements

With the growing application of deep learning (DL) in dental image analysis, numerous datasets and models have been proposed. Periapical radiographs (PR), as one of the most common imaging modalities in clinical dentistry, play a critical role in endodontics. However, due to the high cost of manual annotation and interpretation challenges caused by poor projection and imaging artifacts, publicly available high-quality PR datasets remain scarce, severely limiting the development of DL-based PR analysis models that rely on large-scale annotated data. To address this issue, we introduce PRAD++, a large-scale PR analysis dataset annotated by clinical experts, consisting of 10,000 PR images with multi-level annotations, including 9 pixel-level segmentation categories and 17 image-level classification labels. Building upon PRAD++, we propose PRNet++, an end-to-end PR analysis network. The framework leverages the Multi-scale Wavelet Convolution (MWCN) network and the Channel Fusion Attention (CFA) mechanism to effectively model and integrate multi-scale features. In addition, an Expert Prior Injection (EPI) loss is designed to incorporate domain-specific dental knowledge into the learning process, refining classification predictions based on segmentation outputs to ensure accuracy and clinical interpretability. Extensive experiments on the PRAD++ dataset demonstrate that PRNet++ consistently outperforms state-of-the-art (SOTA) methods, achieving an average DSC of 81.25% for segmentation, alongside macro- and micro-averaged PR-AUCs of 66.58% and 79.10% for classification. Significantly surpassing the runner-up, PRNet++ exhibits enhanced robustness and interpretability in clinically challenging categories. Furthermore, comprehensive ablation and visualization analyses validate the efficacy of individual components and the parameter sensitivity of the EPI loss.