EndoArt: The Science and Craft of Orthograde Retreatment

Course introduction

The first video lecture of the course is dedicated to a brief presentation of the topics that will be covered in the following sessions.

Duration: 7 min

MTA-based protocols and key strategies for successful endodontic retreatment

In this video lecture, Dr. Terauchi presents a comprehensive protocol for successful endodontic retreatments, developed over years of clinical experience in treating complex cases. The session focuses on cases where retreatment is the preferred choice, with particular emphasis on accurate diagnosis, non-odontogenic pain, and the use of MTA as the exclusive obturation material.

The lecture delves into the technical aspects of bypassing ledges and retrieving fractured instruments, as well as MTA-based obturation techniques. A significant focus is dedicated to understanding pain and its implication in post-treatment outcomes.

Dr. Terauchi also shares his clinical data, showing that the consistent use of MTA has drastically reduced the need for surgical intervention.

By the end of the session, clinicians will gain valuable insight into diagnosing challenging cases, managing persistent pain, and maximizing the success rate of non-surgical retreatments through structured, evidence-based protocols.

In particular, this lecture covers the following topics:

• Standardized protocols for retreatment, with MTA as the exclusive canal filling material
• Techniques for bypassing canal ledges and removing broken instruments
• Accurate diagnostic criteria to distinguish odontogenic vs. non-odontogenic cases
• The role of pain assessment and management in improving retreatment outcomes

Duration: 1 h 23 min

Accurate diagnosis in endodontics: from lesion identification to treatment planning

This video lecture explores the critical importance of accurate diagnosis in endodontic retreatment and its direct influence on treatment outcomes.

Through detailed clinical and radiographic criteria, Dr. Terauchi guides clinicians in distinguishing between endodontic and periodontal lesions.

Special attention is given to primary endodontic lesions with secondary periodontal involvement, the diagnostic implications of furcation canals, and the different types of tissue damage (mechanical, chemical, and inflammatory) affecting pulp and periapical health.

The lecture highlights the added diagnostic value of CBCT imaging, particularly in revealing hidden lesions, anatomical complexities, and influencing retreatment protocols.

In particular, this lecture covers the following topics:

• Differentiation of endo-perio lesions and identification of primary endodontic involvement
• Mechanical, chemical, and inflammatory causes of pulpal and periapical damage
• Diagnostic value of CBCT imaging in detecting lesions and anatomical variations
• Role of accurate diagnosis in guiding retreatment strategies and infection control

Duration: 1 h 28 min

Removal of Gutta-percha root fillings

This focused lecture addresses the limitations of gutta-percha as a root canal filling material and its implications for long-term endodontic success. Despite being widely used, gutta-percha lacks intrinsic antibacterial properties and can easily become contaminated by biofilm-forming bacteria.

Dr. Terauchi discusses how fillings that appear radiographically adequate—reaching the canal terminus—do not always result in healing, especially if infected gutta-percha remains within or beyond the canal. The lesson explores how such contamination is a common cause of persistent apical periodontitis and underscores the importance of thorough disinfection and material selection during retreatment procedures.

This session provides valuable insights for clinicians aiming to improve success rates by moving beyond traditional materials and adopting biologically sound treatment approaches.

In particular, this lecture covers the following topics:

• The biological limitations of gutta-percha in preventing reinfection
• The role of biofilm contamination in persistent apical periodontitis
• Why radiographic adequacy of root fillings doesn't guarantee healing
• Critical considerations for material choice in endodontic retreatment

Duration: 28 min

How to remove the gutta percha filling materials

This hands-on LIVE DEMO session complements the previous theoretical lecture by showing the clinical application of gutta-percha removal techniques on a simulation model.

Dr. Terauchi demonstrates step by step how to efficiently remove gutta-percha using a dedicated kit, combining manual and ultrasonic instruments.

The session focuses on real-time handling of hand files and three different ultrasonic tips, offering practical guidance on how to approach complex retreatment cases where existing filling materials must be eliminated with precision.

This live demonstration provides clinicians with a clear and replicable protocol to improve efficiency and predictability during the gutta-percha removal phase of endodontic retreatment.

In particular, this lecture covers the following topics:

• Introduction and use of the gutta-percha removal kit
• Manual techniques with specialized hand instruments
• Application of three ultrasonic tips in different clinical situations
• Step-by-step protocol for effective and safe gutta-percha extraction

Duration: 21 min

Root filling materials removal

This detailed video lecture focuses on advanced techniques for removing set MTA obturation material using ultrasonic tips combined with chemical agents such as EDTA.

Dr. Terauchi demonstrates how to effectively disrupt and dissolve hardened MTA within the canal, emphasizing the synergy between mechanical and chemical methods.

The lecture also covers protocols for removing biofilms by combining rotary and hand instruments with ultrasonic irrigation, ensuring thorough canal disinfection.

Special attention is given to managing ledged canals, including the characteristics of ledge formation and the appropriate materials and techniques to bypass them safely.

Clinicians will gain a comprehensive understanding of how to handle challenging retreatment cases involving MTA and biofilm removal while maintaining canal integrity.

In particular, this lecture covers the following topics:

• Ultrasonic disruption of set MTA and EDTA chemical dissolution
• Combined mechanical and ultrasonic techniques for biofilm removal
• Efficient irrigation protocols for enhanced canal cleanliness
• Strategies and materials for bypassing and managing ledged canals

Duration: 49 min

Demo for bypassing the ledges

In this video lecture, Dr. Terauchi introduces refined techniques for bypassing non-visible canal ledges, an advanced challenge often encountered during retreatment procedures.

When pre-curving the tip becomes impractical, innovative solutions like the newly designed fan-shaped ultrasonic tips offer improved control and flexibility.

The session reviews three main techniques: the hand instrumentation technique, the slow rotation technique, and the 90-degree T-mode approach.

Emphasis is placed on file selection, rotational speed modulation, and maintaining tip alignment with the original canal path to prevent iatrogenic damage.

Participants will discover practical tools and strategies to approach ledge bypassing with confidence and precision, even in the most complex root canal anatomies.

In particular, this lecture covers the following topics:

• Use of fan-shaped ultrasonic tips for navigating non-visible ledges
• Hand instrumentation technique and the importance of maintaining tip curvature
• Slow rotation and 90-degree T-mode techniques for bypassing complex curvatures
• Selection of files and insertion strategies to preserve canal anatomy

Duration: 1 h 04 min

LIVE DEMO: bypassing non-visible ledges: practical techniques on model

This LIVE DEMO session puts into practice the key techniques discussed in the previous lecture on bypassing non-visible canal ledges.

Using a simulation model, Dr. Terauchi demonstrates how to safely and effectively navigate ledged canals through a combination of hand instrumentation, controlled rotation, and fan-shaped ultrasonic tips.

The demo offers a step-by-step visualization of instrument handling, file selection, and tip orientation—providing clinicians with clear, actionable methods for maintaining the original canal path and minimizing procedural errors.

This hands-on session is essential for endodontists seeking to master precision-ledged bypassing in anatomically complex retreatment scenarios.

In particular, this lecture covers the following topics:

• Real-time application of hand instrumentation and slow rotation techniques
• Use of fan-shaped ultrasonic tips to improve access and control
• File selection and insertion dynamics in ledged canals
• Practical strategies to maintain the original canal trajectory

Duration: 26 min

MTA obturations in endodontic retreatment: a biological alternative to gutta-percha

This lesson explores the rationale behind the use of MTA as a root filling material in non-surgical endodontic retreatments, offering a biologically superior alternative to traditional gutta-percha.

Dr. Terauchi analyzes the limitations of gutta-percha and sealer-based fillings, particularly their poor sealability and susceptibility to reinfection.

The session presents a direct comparison between the clinical protocols and anatomical preparations required for MTA versus gutta-percha obturation. Emphasis is placed on the long-term benefits of MTA, including enhanced biocompatibility, sealing ability, and its capacity to reduce the need for surgical interventions.

This presentation is particularly valuable for clinicians aiming to improve retreatment outcomes by integrating more reliable and biologically stable materials.

In particular, this lecture covers the following topics:

• Why MTA obturation is preferred over gutta-percha in retreatment cases
• Limitations of traditional gutta-percha and sealer fillings
• Step-by-step comparison: MTA vs. gutta-percha preparation techniques
• Clinical benefits and sealing properties of MTA in complex retreatments

Duration: 1 h 28 min

LIVE DEMO: MTA obturations in retreatment: step-by-step application on model

In this LIVE DEMO, Dr. Terauchi shows the clinical application of MTA obturation techniques in endodontic retreatments using a simulation model. Building on the theoretical concepts presented in the previous lecture, the session focuses on how to properly prepare the canal system and deliver MTA with precision and control.

The demonstration contrasts the procedural nuances between MTA and gutta-percha fillings, highlighting the specific instrumentation and timing required for successful placement. Special attention is given to handling MTA’s physical properties and ensuring a hermetic seal to optimize treatment outcomes.

This hands-on lesson provides clinicians with a replicable protocol for incorporating MTA into retreatment workflows, aiming for long-term clinical success and reduced surgical needs.

In particular, this lecture covers the following topics:

• Clinical steps for preparing the canal for MTA obturation
• Techniques and instruments used to place MTA effectively
• Differences in handling and delivery between MTA and gutta-percha
• Key tips to achieve a dense and biologically stable root filling

Duration: 18 min

Minimally invasive and predictable removal of broken instruments

This lesson explores the critical factors that influence the success of broken file removal in endodontic retreatment. Through the analysis of a challenging clinical case involving two fractured instruments—one visible and the other non-visible, both extruded into bone—Dr. Terauchi outlines the decision-making process that drives predictability and clinical outcomes.

A detailed comparison is made between removal strategies for visible and non-visible fragments, including canal enlargement, ultrasonic tip usage, and space creation along the inner canal wall. The lecture emphasizes the diagnostic importance of CBCT imaging for precise localization, length assessment, and treatment planning.

With a focus on minimizing dentin loss while maximizing removal efficiency, this session offers a step-by-step guide for clinicians aiming to master one of the most delicate procedures in modern endodontics.

In particular, this lecture covers the following topics:

• Clinical criteria and imaging techniques to plan fractured instrument removal
• Differences in approach for visible vs. non-visible broken files
• Step-by-step use of ultrasonic tips for conservative and effective removal
• The role of retained instruments in healing outcomes and retreatment success

Duration: 1 h 26 min

Advanced ultrasonic techniques for removing non-visible broken files in severely curved canals

This lecture focuses on the complex challenge of removing non-visible broken instruments located beyond severe canal curvatures, exceeding 30 degrees. Dr. Terauchi presents advanced ultrasonic instrumentation strategies specifically developed to navigate and access fractured files in anatomically demanding situations.

Two preparation techniques are compared—180-degree and 90-degree approaches—detailing the scenarios in which each method offers optimal visibility and access. The lecture outlines critical steps for conservative dentin removal, tip positioning, and the precise manipulation of ultrasonic energy to safely dislodge fragments embedded deep within curved canals.

By mastering these advanced techniques, clinicians can significantly improve their success rate in fractured instrument retrieval while preserving tooth structure and minimizing iatrogenic damage.

• In particular, this lecture covers the following topics:180° vs. 90° canal preparation techniques for fractured file access
• Strategic removal of broken files beyond severe (>30°) canal curves
• Step-by-step application of ultrasonic tips in curved canal anatomy
• Clinical tips to optimize visualization, access, and dentin preservation

Duration: 1 h 02 min

LIVE DEMO: Ultrasonic removal of non-visible broken files in severely curved canals

In this LIVE DEMO, Dr. Terauchi demonstrates the clinical application of advanced ultrasonic techniques for removing non-visible fractured instruments located beyond severely curved root canals. Using a simulation model, he replicates the anatomical challenges posed by curvatures greater than 30°, offering a step-by-step visual guide to the 180-degree and 90-degree preparation strategies.

The session focuses on optimizing access and visualization without compromising dentin integrity. Viewers will gain practical insights into tip selection, movement control, and precision targeting of the broken fragment within tight canal curvatures.

This hands-on demonstration reinforces the theoretical concepts covered in the previous lecture and equips clinicians with actionable protocols for one of endodontics’ most technically demanding procedures.

In particular, this lecture covers the following topics:

• Practical application of the 180° and 90° ultrasonic access techniques
• Step-by-step removal of non-visible files beyond curved segments
• Instrument selection and tip control for enhanced precision and safety
• Strategies to minimize dentin sacrifice while maximizing success rates

Duration: 1 h 02 min

Ten second rule for instrument removal

This lesson presents a preliminary study exploring the time-efficiency and predictability of ultrasonic removal of non-visible broken instruments during endodontic retreatment. Results show a striking pattern: when ultrasonic tips successfully mobilize a fragment, removal typically occurs within 10 seconds. If the file does not move within that window, attempts beyond 10 minutes often fail.

Dr. Terauchi discusses the anatomical and mechanical factors that affect this predictability, such as file length, diameter, and canal curvature severity. He also demonstrates a protocol combining ultrasonic tips with additional tools like Piezoflow and Endo Shaper to enhance removal success in complex cases. Clinicians will gain a deeper understanding of when to persist, when to reconsider, and which techniques can increase the odds of safely retrieving fractured files.

In particular, this lecture covers the following topics:

• Clinical relevance of the “10-second success rule” in fractured file removal
• How fragment size, length, and canal curvature impact ultrasonic effectiveness
• Use of complementary tools: Piezoflow, ultrasonic tips, and Endo Shaper
• Strategic decision-making when ultrasonic removal becomes inefficient

Duration: 40 min

LIVE DEMO: strategies for removing non-visible broken files with ultrasonics

In this LIVE DEMO session, Dr. Terauchi shows the application of ultrasonic techniques for removing non-visible broken instruments within severely curved canals. Participants will discover the “10-second rule” as a predictor of removal success: if the fragment does not begin to move within 10 seconds, prolonged attempts are unlikely to succeed.

Using a high-fidelity simulation model, Dr. Terauchi walks through various removal protocols involving ultrasonic tips, Piezoflow, and Endo Shaper systems. The session illustrates how file length, diameter, and curvature influence access and effectiveness, and provides visual guidance on adjusting strategies in cases of limited response.

This demonstration bridges theory and practice, equipping clinicians with real-time decision-making tools and technical accuracy in one of endodontics’ most delicate procedures.

In particular, this lecture covers the following topics:

• Live demonstration of the “10-second rule” in fractured file removal
• Use of ultrasonic tips, Piezoflow, and Endo Shaper on a simulation model
• Adjusting technique based on file visibility, anatomy, and curvature
• Clinical decision-making when ultrasonic efforts become inefficient

Duration: 41 min

Advanced techniques for long broken file removal

This lesson focuses on the clinical management of long or deeply positioned broken instruments, particularly those located around severe canal curvatures. Dr. Terauchi presents the use of burs to carefully access and retrieve longer fragments, minimizing dentin sacrifice and procedural risks.

The session highlights the integration of ultrasonic irrigation systems like Piezoflow, which assist in dislodging fragments through enhanced acoustic streaming and debris clearance. A detailed flowchart is also provided, outlining the clinical decision-making process based on file visibility, location, and canal anatomy.

Through a combination of precision instrumentation and step-by-step planning, clinicians will be better equipped to approach even the most complex instrument removal cases.

In particular, this lecture covers the following topics:

• Rotary bur techniques for safely accessing and retrieving long broken files
• Application of Piezoflow for ultrasonic irrigation and biofilm disruption
• Management of broken instruments located around severe curvatures
• Strategic treatment planning through a structured removal flowchart

Duration: 8 min

LIVE DEMO: Practical removal of long broken files using rotary burs and piezoflow

In this LIVE DEMO, Dr. Terauchi demonstrates the practical application of advanced techniques for removing long broken files, especially those located around severe canal curvatures. Using a detailed simulation model, he showcases the use of rotary burs for precise dentin removal and fragment access, combined with Piezoflow ultrasonic irrigation to enhance fragment mobilization and cleaning.

The demonstration also walks through a clinical flowchart guiding treatment planning and decision-making during the removal process. This hands-on session bridges theoretical concepts with real-time practice, providing valuable insights for clinicians facing challenging fractured instrument cases.

In particular, this lecture covers the following topics:

• Use of rotary burs for accessing and removing long broken instruments
• Application of Piezoflow ultrasonic irrigation to assist fragment removal
• Techniques for managing broken files in severe canal curvatures
• Step-by-step clinical workflow for instrument removal decision-making

Duration: 48 min