Comprehensive treatment of dens invaginatus type IIIBGašpirc, Boris (Avtor) Hitij, Tomaž (Avtor) Hočevar, Luka (Avtor) dens invaginatusimmature permanent toothinterdisciplinary managementIntroduction. Dens invaginatus (DI) is a rare developmental anomaly characterized by invagination of the enamel organ into the dental papilla, creating complex internal anatomy. Type III DI, according to Oehlers’ classification, presents diagnostic and therapeutic challenges, especially in teeth with incomplete root development. Early diagnosis and proper management are crucial to prevent pulpal and periodontal complications, preserve tooth vitality, function and aesthetics. The aim of this report is to describe the long-term interdisciplinary management of a rare DI type IIIB, highlighting diagnostic challenges, treatment strategies, successful tooth preservation, and importance of long-time controls. Case outline. A maxillary lateral permanent incisor with DI type IIIB in a 9-year-old boy presented with peri-invagination periodontitis while maintaining pulp vitality and incomplete root formation. A staged, minimally invasive approach was adopted, initially focusing on periodontal surgery and regenerative therapy to control infection while preserving pulp vitality and allowing continued root development. After more than two years of successful vitality maintenance, irreversible pulpitis developed, requiring complex orthograde root canal treatment followed by apical surgery. Long-term follow-up exceeding nine years demonstrated complete periapical healing, stable periodontal conditions, functional integrity, and retention of the tooth in the dental arch. Conclusion. Early diagnosis of DI is essential, as type III cases pose major challenges to pulp preservation and root canal treatment and are often considered for extraction. This case shows that long-term tooth preservation is achievable despite complex anatomy using an individualized, interdisciplinary approach.20262026-08-06 10:09:15Neznano31703UDK: 616.314-007-089ISSN pri članku: 0370-8179DOI: 10.2298/SARH260219048GCOBISS_ID: 284991747slNa spletni strani revije Srpski Arhiv Za Celokupno Lekarstvo (Serbian Archives of Medicine) navedeno: Serbian Archives of Medicine is an Open Access Journal. All articles can be downloaded free of charge and used in accordance with the Creative Commons AttributionNonCommercial 4.0 International (CC BY-NC) licence (http://www.srpskiarhiv.rs/en/home/, http://www.srpskiarhiv.rs/global/doc/Uputstvo_October_2025.pdf).