Research progress on the clinical diagnosis of secondary vertical root fractures

Vertical root fracture is a type of longitudinal crack originating from the roots of teeth that can occur in vital teeth and teeth after root canal treatment. It is a hard tissue disease of teeth with a complex etiology and poor prognosis. The vertical root fracture that occurs in teeth after pulp treatment is called secondary vertical root fracture (SVRF). A comprehensive judgment should be made based on clinical signs such as pain, swelling, tooth looseness, sinus located near the gum edge, and deep and narrow isolated periodontal pockets, as well as apical films such as periodontal membrane widening, vertical and root bone loss, and “halo” or “J” shaped transmission shadows around the root. For teeth suspected of longitudinal root fractures, three-dimensional imaging such as cone beam computed tomography (CBCT) should be used to assist in the diagnosis. If CBCT shows a defect in the buccal or lingual bone plate, it can increase the possibility of diagnosing SVRF. The setting of CBCT parameters should be optimized by using small field CBCT, enhancing dye-assisted applications, and metal artifact reduction (MAR) tools to reduce the impact of artifacts and improve the accuracy of CBCT diagnosis of SVRF. Magnetic resonance imaging (MRI), digital subtraction radiography (DSR), optical coherence tomography (OCT), and other imaging techniques can detect cracks of different widths, and artificial intelligence (AI) diagnostic technology and predictive models provide further auxiliary means for SVRF diagnosis. SVRF cannot be determined through noninvasive methods, and the final diagnostic method is to detect the presence of SVRF through direct observation within the root canal and during flap surgery.