Background <p>External cervical resorption (ECR) is a dental condition characterized by irreversible loss of tooth structure due to periodontal tissue activity, with varied treatment approaches. Evidence on outcomes mainly comes from retrospective studies in specialized settings with limited follow-up, whereas population-level real-world data are scarce. The Swedish National Dental Health Registry (SNDHR) provides a unique opportunity to examine treatment patterns and long-term outcomes of ECR at a national level. This study aimed to map treatment modalities used for teeth diagnosed with ECR in routine dental care and to assess tooth survival over extended periods, as well as to explore associations with available patient- and treatment-related factors within the constraints of registry data.</p> Methods <p>Data from the SNDHR between 2009 and 2018 were used to identify adult patients with ECR and associated treatments; only one affected tooth per patient was included, and wisdom teeth were excluded. Teeth receiving initial conservative treatment were followed longitudinally in the registry until extraction, emigration, death, or the end of follow-up in 2023. Descriptive statistics, Kaplan–Meier survival analysis, and Cox regression models were applied to evaluate treatment patterns and factors associated with tooth survival.</p> Results <p>In total, 14,881 teeth with ECR were identified (annual range: 1,132–2,071), of which 42.8% were extracted as the initial treatment and 57.2% received an initial conservative treatment (51.9% female; mean age 60.7 years, standard deviation [SD] 16.7; range 19–99), with or without surgery. The cumulative survival of conservatively treated teeth was 82.7% (standard error [SE] 0.4%) at 5 years, 74.9% (SE 0.5%) at 10 years, and 67.8% (SE 2.1%) at 15 years. In multivariate analyses, increasing age, fewer remaining teeth, molar involvement, and surgical treatment were associated with a higher risk of extraction, whereas root canal treatment performed within ±90 days of the initial treatment had no significant impact on tooth survival.</p> Conclusion <p>In conclusion, this nationwide registry-based study provides population-level, long-term survival estimates for teeth affected by ECR and managed in routine dental practice. Although interpretation is limited by the lack of detailed clinical information inherent to registry data, the findings offer real-world evidence suggesting that teeth selected for conservative management demonstrate favourable long-term survival.</p>