Prevalence of Vertical Root Fractures in Root Filled Teeth and Their Clinical and Radiographic Risk Factors: A Modern Case-Control Analysis Based on Surgical Diagnosis

Introduction Vertical root fractures (VRFs) are challenging in endodontic diagnosis. This study determined VRF prevalence and risk factors in root-filled teeth (RFT) requiring endodontic surgery. Methods From 411 RFT that underwent endodontic surgery (2005–2022), 130 VRF cases and 260 randomly selected controls were analyzed. Demographic, clinical, and radiographic data were collected from dental records and images. Multiple imputations addressed missing data. Univariable and multivariable logistic regression analyses with robust standard errors to account for the clustering of multiple teeth within the same patient were performed, with subanalyses for teeth with intraradicular posts and molars. VRF characteristics were analyzed in individuals with available cone beam computed tomography images. Results VRF prevalence was 31.63% among RFT undergoing endodontic surgery. Significant risk factors included age (adjusted odds ratio [aOR] = 1.02), probing depth ≥5 mm (aOR = 2.37), isolated perilateral radiolucency (aOR = 4.05), halo radiolucency (aOR = 2.70), overfilled root canal (aOR = 2.11), and root canal space-to-root-width ratio >1/3 (aOR = 1.52). For teeth with posts, a post space-to-root-width ratio >1/3 increased VRF risk (unadjusted OR [uOR] = 2.46). Cone beam computed tomography findings revealed the absence of the buccal plate (uOR = 1.74) and space between the cortical plate and root surface (uOR = 2.73) as significant factors. Conclusions VRFs affected nearly one-third of RFT requiring endodontic surgery; major risk factors included older age, overfilled root canals, and excessive root canal space-to-root-width ratio. VRF-associated clinical and radiographic signs included probing depth ≥5 mm, isolated perilateral radiolucency, and halo radiolucency.