Initial root canal therapy does not always result in healing for a multitude of reasons. Retreatment could also result in another failure unless the causes of the failure are identified and removed.  First, an accurate diagnosis is always the key to success especially in retreatment. Second, failure to adequately disinfect the root canal system may result in nonhealing if the causes of the failure are mainly odontogenic. Bacteria may persist following initial treatment due to the areas that were inaccessible to instrumentation and irrigation. Causes of treatment failure may include inaccurate diagnosis, lack of tooth isolation; inadequate cleaning, shaping, and irrigation; and an incomplete obturation. In addition, iatrogenic accidents such as separated instruments and ledge formation can also be serious problems leading to failure because of the inability to disinfect the canal system apical to those obstructions. In retreatment those mishaps that can adversely impact the treatment outcomes should be properly managed. Therefore, in the one-day lecture, the ideal management of those nonhealing cases will be discussed and presented:

Accurate diagnosis and treatment planning

• How to differentiate odontogenic pain from non-odontogenic pain
• Diagnosis in retreatment

Removal of gutta-percha root filling materials and biofilms

• Why do the gutta-percha root fillings have to be removed in retreatment?
• What is the most efficient technique to remove root fillings?

Updated techniques to remove broken files

• Preparation techniques for broken file removal
• Broken file removal techniques

Management of ledged canals

• How do you prevent ledge formation?
• What are the predictable and practical techniques to bypass ledges

MTA obturation in retreatment (Perforation repair)

• Comparisons of clinical properties and root canal preparation between gutta-pecha and MTA as a root filling material
• Predictable techniques for MTA obturation

First part
Vital Pulp Therapy in Deep Caries: Rethinking the Irreversible Pulpitis Diagnosis
Pulpectomy has long been considered the standard treatment for teeth with carious pulp exposure and those diagnosed with irreversible pulpitis. However, histopathological evidence challenges this approach by showing that pulp necrosis is a gradual process. In its early stages, necrosis is confined to the superficial pulp, with a transitional zone leading to deeper vital but inflamed tissue. The advancing front of infection is consistently confronted by a dense accumulation of polymorphonuclear leukocytes, which gradually gives way to chronic mononuclear inflammatory cells, and eventually, relatively healthy, non-inflamed tissue at the periphery. This lecture will present high-definition clinical video documentation demonstrating how to visually identify the infected pulp front, selectively remove diseased tissue through partial pulpotomy, and preserve the vitality of the remaining pulp. The exposed pulp wound is then protected with biocompatible and potentially bioactive materials, supporting healing and continued function. This biologically driven approach offers a conservative, evidence-based alternative to full pulpectomy, even in cases traditionally diagnosed as irreversible pulpitis.

Second part
Root Canal Infections: A Multifaceted Biological and Clinical Challenge
This lecture explores the complex progression of pulp degeneration and microbial colonization within the root canal system. Special emphasis will be placed on the formation and organization of bacterial biofilms, not only within the main canals but also in lateral canals, isthmuses, dentinal tubules, and other anatomical complexities that often escape traditional instrumentation and irrigation. Advanced histological and microbiological evidence will be presented to demonstrate how biofilms may extend beyond the confines of the root canal system, contributing to extraradicular infections, a condition that challenges conventional endodontic approaches and may require surgical intervention.
The session will also critically examine key clinical decision points, such as the management of lateral canals and the determination of the apical extent of instrumentation and obturation. Controversial topics will be addressed in the light of current scientific evidence, including the biological relevance of achieving apical patency and the clinical significance of so-called “missed anatomy.”