Assessment of volumetric changes after regenerative endodontic procedures using semiautomated and 3D U-NET automated CBCT segmentation: a retrospective cohort study

This retrospective cohort study evaluated volumetric changes in dental pulp and root structure of necrotic teeth after regenerative endodontic procedures (REPs) compared to contralateral counterparts (CON) using semiautomated segmentation and a 3D UNet model. Data from 23 teeth with REPs and their CON were analyzed. Semiautomated segmentation was performed using ITK-SNAP and 3D Slicer CMF on scans taken before and 12 months post-treatment. Measurements included root length, volume changes (dentinal wall, intracanal calcification, and pulp) below the Biodentine plug. Automated pulpal segmentation utilized a 3D UNet model trained on 400 samples from the ToothFairy dataset, achieving a Dice Similarity Index of 0.76, Intersection over Union of 0.61, and Hausdorff distance of 2.15. REP teeth showed no significant differences in root volume or dentinal changes compared to CON. REP significantly reduced pulp volume in mature teeth (-4.86 mm3 vs. -1.34 mm3, p = 0.05), with lesser changes in immature teeth (-3.20 mm3 vs. -6.44 mm3, p = 0.12). Significant root length differences (p = 0.04) were observed between mature and immature teeth with REPs. The 3D UNet model and semi-automated method for volumetric pulp assessment showed excellent agreement (ICC = 0.92, p < 0.001). Bland–Altman plots indicated good agreement between the two methods in measuring pulpal volumetric changes. REPs yield comparable findings to CON in root volume and dentinal wall changes, while significantly reduced pulp volume in mature teeth compared to CON. Distinct patterns of intracanal calcification and root length changes between mature and immature teeth were identified. A deep learning model can expedite post-REP pulp volume evaluations. Understanding volumetric changes in dental pulp and root structure is vital for assessing REP success, facilitating clinical decision-making, and improving outcomes in regenerative endodontics.