Researchers have found in a new research that primary teeth affected by Regional odontodysplasia show marked microstructural abnormalities and weakened mechanical properties, highlighting the importance of early intervention and long-term monitoring to prevent further dental complication.Regional odontodysplasia (ROD) is a rare, localized disorder of tooth hard tissues that can affect primary and permanent dentitions. However, its definitive etiology remains unclear and only a few studies have reported the detailed microstructures and mechanical characteristics of the affected teeth. This study investigates the microstructural and mechanical characteristics of primary teeth affected by Regional odontodysplasia . A total of two Regional odontodysplasia -affected primary teeth from two different cases underwent clinical examinations. In addition to control samples of caries-free retained primary teeth, the affected samples were examined using micro-computed tomography (micro-CT), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and nanoindentation analysis. Results: Clinical findings revealed yellowish discoloration, rough surfaces, and root resorption on the affected teeth. Radiographs indicated hypocalcified enamel, widened pulp chambers, and delayed development of permanent teeth. Micro-CT showed affected teeth with thinner and uneven enamel, disordered dentin, and reduced mineral density. X-ray diffraction analysis found reduced crystallinity. Scanning electron microscopy and TEM analyses revealed hypoplastic and loosely packed enamel crystals, whereas dentin exhibited disorganized collagen fibrils and poorly mineralized crystals. Energy-dispersive X-ray spectroscopy analysis showed a reduced calcium/phosphorus ratio and an increased magnesium/calcium ratio in the affected enamel. Nanoindentation tests found reduced hardness and elastic modulus in Regional odontodysplasia -affected enamel compared with control teeth.Regional odontodysplasia -affected primary teeth display significant microstructural abnormalities and compromised mechanical properties, underscoring the need for early intervention and long-term monitoring to prevent complications.Reference:Jiang, W., Shen, M., Wang, J., Bian, M., Zheng, H., Zhou, Z., Shi, Y., & Wu, Z. (2026). Microstructures and mechanical characteristics of primary teeth affected by regional odontodysplasia. Journal of Applied Oral Science, 34, e20250499. https://doi.org/10.1590/1678-7765-2025-0499Keywords:Study , Odontodysplasia; Primary teeth; X-Ray microtomography; Electron microscope tomography, Jiang, W., Shen, M., Wang, J., Bian, M., Zheng, H., Zhou, Z., Shi, Y., & Wu, Z.