Negative Pressure Disinfection and Obturation of a Mandibular Premolar With Type IIIb Dens Invaginatus: Case Report and Treatment Considerations

Dens invaginatus presents complex anatomical challenges in endodontic treatment, particularly in its severe form, Type III, where the invagination extends through the root and into the periapical tissue. The intricate morphology often complicates effective disinfection and obturation, leading to potentially higher treatment failure rates. The present case describes the noninstrumentation root canal treatment of a dens invaginatus Type IIIb in a second mandibular premolar associated with apical periodontitis. After CBCT mapping of the complex anatomy, modified negative pressure irrigation and passive ultrasonic activation were used to disinfect the complex anatomy. A CBCT-assisted negative pressure bioceramic obturation technique was used to seal the extraordinary anatomy. The 5-year CBCT follow-up shows healing of the periapical lesion and the optimal distribution of the obturation material in the highly complex anatomy.