The Survival and Success of Teeth With External Cervical Resorption: A Multi-Centre, Retrospective Study

To evaluate the survival and success outcomes of teeth affected by external cervical resorption (ECR) managed using three distinct treatment strategies, with periapical radiographs and small field of view cone beam computed tomography used for diagnosis and treatment planning.

This retrospective, multi-centre cohort study analysed 296 teeth diagnosed with ECR across five specialist endodontic practices between 2009 and 2024. Management approaches included periodic review (Treatment 1), external repair with or without endodontic intervention (Treatment 2), and internal repair (Treatment 3). Treatment selection was based on clinical and radiographic characteristics, including lesion accessibility, symptomatology, and the presence of bone-like tissue. Patients underwent annual clinical and radiographic review. The primary outcome was tooth survival; secondary outcomes included success (asymptomatic and healed) and failure (extraction due to progression or non-restorability). Kaplan-Meier survival estimates and Cox proportional hazards models were applied.

A total of 296 teeth from 233 patients were followed for a mean of 2.9 years (range: 12-123 months). Estimated cumulative survival rates at 1, 2, 5, 7, and 10 years were 95.5%, 93.3%, 85.7%, 80.5%, and 80.5%, respectively. Multivariable analysis demonstrated that internal repair and higher Patel lesion classifications, particularly circumferential involvement greater than 180°, were associated with a higher extraction hazard. The Heithersay classification was not significantly associated with survival. Estimated cumulative survival rates were 93.6%, 90.2%, and 59.1% for Treatments 1, 2, and 3, respectively.

Higher estimated survival was observed among teeth selected for periodic review, followed by external repair and internal repair. Greater three-dimensional lesion extent, > 180°, was associated with an increased extraction hazard. Treatment selection was influenced by lesion characteristics and clinical judgement; differences between treatment groups should be interpreted as associations rather than evidence of treatment superiority. External repair remained viable, whereas internal repair was associated with a greater risk of failure. The Patel (3D) classification was more strongly associated with survival outcomes than the Heithersay (2D) classification and supports detailed lesion characterization and treatment planning. Treatment decisions should be guided by lesion extent, accessibility, symptoms, and evidence of reparative activity. The findings represent associations observed within a retrospective cohort.