Common Errors during Root Canal Treatment

Endodontic procedures are intricate and require precision, attention to detail, and a thorough understanding of root canal anatomy and physiology. Despite advancements in dental techniques and technology, procedural errors remain a significant challenge during root canal treatment. These errors can compromise the success of the treatment, leading to discomfort, reinfection, or even tooth loss for the patient.

In this blog, we will explore the common procedural errors encountered during various stages of root canal therapy — access opening, canal shaping and cleaning, and obturation. Each stage presents unique challenges, from treating the wrong tooth or missing canal orifices to more severe complications like ledge formation, instrument separation, or irrigant-related mishaps. By understanding these errors, their causes, and ways to prevent them, clinicians can ensure a higher success rate and improved patient outcomes.

Classification of Procedural errors:

1. Related to access opening of the pulp space
2. Related to canal shaping and cleaning
3. Related to obturation

I. Procedural errors related to access opening of the pulp space

The main errors and challenges faced during access opening procedures are as follows:

• Treating the wrong tooth:This can occur due to an incorrect history or an improper diagnosis of the tooth. In addition, failing to consider radiographic evidence and relying solely on clinical symptoms often leads to errors, especially in cases of referred pain. To ensure accurate diagnosis and treatment planning, a detailed history, thorough clinical examination, and radiographic evidence must be considered. Pre-marking the tooth to be treated can further reduce the chances of treating the wrong tooth. Moreover, preparing the initial access cavity before placing a rubber dam can help prevent such errors.

• Incomplete removal of caries: Leaving caries partially untreated can result in a weakened tooth structure even after endodontic treatment. Clinicians often focus on removing the infected carious tissue but may overlook the affected carious areas, which can cause reinfection and eventual failure of the treatment due to coronal leakage by the secondary caries. Therefore, complete removal of the carious lesion should be a primary focus before proceeding with the access opening.

• Access opening through full-coverage restoration: When a tooth requiring endodontic treatment already has an existing crown with a good marginal seal, crown removal may not be necessary. However, maintaining proper bur orientation and parallelism with the tooth’s long axis during access opening can be challenging. Failure to do so may lead to incomplete caries removal, perforations, or inadequate cleaning and shaping, ultimately causing endodontic failures.

• Inability to locate extra canals (missed canal orifices): Failing to locate all canals is one of the primary reasons for endodontic failure. This often arises from insufficient knowledge of canal anatomy, improper access cavity design, or incomplete deroofing of the pulp chamber. Preoperative periapical radiographs and radiographs taken during cleaning and shaping from different angulations can help identify all the existing canals more effectively.

• Iatrogenic perforations: Cervical perforations typically result from incorrect bur direction, such as when the bur is not aligned parallel to the tooth’s long axis. During caries removal, care must be taken to avoid removing healthy enamel and dentin to prevent such complications. The depth and angulation of access bur penetration should be confirmed before proceeding with access cavity design. Perforation at the furcation is also quite common, for this excessive flooding of the chamber with blood should be promptly evaluated, as it is often the first sign of a potential perforation.

II. Procedural errors related to canal shaping and cleaning

Common Procedural Errors Encountered During Canal Shaping and Cleaning:

• Canal blockage and ledge formation: Canal blockage typically occurs due to apical compaction by dentinal debris during the shaping and cleaning of the root canal. To prevent this, instrumentation should be performed sequentially, and working length recapitulation should be done periodically. Additionally, copious amounts of irrigants should be used, and regular inspection of the files for wear is essential.
  A ledge refers to an artificially created deviation in the root canal wall, which obstructs the passage of an instrument to the apex of an otherwise patent canal. It can be caused by incorrect assessment of root canal curvature, errors in determining root canal length, or using non-curved instruments in highly curved canals. Regular recapitulation with smaller files, maintaining canal patency, working passively without forcing files, and taking good preoperative radiographs can help prevent ledge formation. Management involves using thermoplasticized gutta-percha to seal and close the canal.

• Deviation from normal canal anatomy: Deviations in canal anatomy can present as zipping, elbow formation, or transportation. Zipping refers to apical transportation of a curved canal caused by improper shaping techniques, while transportation refers to a deviation of files externally from the original path during shaping and cleaning, especially when larger files are used. Initial shaping with smaller files minimizes this risk. Elbow formation, often associated with zipping, occurs as a narrow region of the root canal at the point of maximum curvature as a result of the irregular widening that occurs coronally along the inner aspect and apically along the outer aspect of the curve.

• Separation of instruments: Instrument separation usually happens when an instrument is forced into the dentinal structure or overused. Fracturing of the instrument in the apical third is often difficult to bypass, while in the coronal third, the separated instrument can usually be removed or negotiated to the apex. Prognosis and management depend on the level of instrument separation (coronal, middle, or apical third), instrument size, degree of infection, operator skill, patient motivation, and the planned treatment course. Many instrument retrieval kits are available on the market today, widely used by endodontists. These kits can be conveniently explored on our website, DentalKart.

• Obstruction by previous obturating materials: Retreatment of a previously endodontically treated tooth requires the complete removal of gutta-percha. This can be achieved using several techniques, including mechanical instrumentation with H files or Gates-Glidden drills, heat to soften and sear the gutta-percha, gutta-percha solvents, ultrasonics, or a combination of these methods.

III. Procedural errors related to obturation

• Underfilling of gutta-percha: This usually occurs due to a loss of working length caused by irregular recapitulation and insufficient irrigation. A small-sized file can be used for recapitulation to help dislodge the packed dentinal mud, along with copious irrigation using sodium hypochlorite. A confirmatory radiograph with the master cone should be taken before completing the obturation process.
• Overfilling of gutta-percha: Overextension of gutta-percha into the canal often results from the loss of apical constriction caused by perforation due to over-instrumentation or inaccurate working length determination. Nerve paresthesia may result from overextension caused by overfilling. This can be prevented by accurate working length estimation using an apex locator and radiographs. The master cone should be evaluated in the apical third before proceeding with obturation. In wide canals, the master cone should be placed slightly short of the apex so that it flows into the constriction and apical ramifications during thermal compaction. Apical stops are mandatory, and reproducible reference points must be identified and consistently followed throughout the treatment to prevent overextension.

Other related mishaps

• Aspiration or ingestion of endodontic instruments: Aspiration typically occurs when the procedure is performed without the use of a rubber dam. Such accidents can be life-threatening and may result in legal action against the dentist. This is a preventable procedural error, making it essential to use a rubber dam to avoid such mishaps.

• Tissue emphysema: Tissue emphysema is primarily caused by two factors: a blast of air used to dry a canal or exhaust air from a high-speed drill directed toward tissue instead of being evacuated to the rear of the handpiece during apical surgery. This results in rapid swelling, crepitus, and erythema. To prevent this, dentists should avoid blowing air into an open canal.
• Vertical root fracture: Vertical root fractures may occur due to excessive force during lateral compaction of gutta-percha during obturation. Diagnosis involves hearing a crepitus-like or crunching sound along with a pain response from the patient. These fractures can be prevented by avoiding over-preparation of the canal and applying controlled and minimal force during the obturation process.
• Irrigant-related mishaps: Common irrigant solutions, such as sodium hypochlorite, can cause periradicular tissue necrosis, particularly in cases involving an open apex. The severity of damage can range from mild to severe. Sodium hypochlorite extruded beyond the root canal may cause chemical burns, leading to necrosis of periradicular tissues, both intraorally and extraorally, affecting the skin and subcutaneous tissues. This can be prevented by irrigating with a copious saline solution to rinse off sodium hypochlorite from the periradicular areas, along with the administration of hydrocortisone injections.

Conclusion

Root canal therapy is a cornerstone of endodontics, demanding precision and an in-depth understanding of procedural nuances. By staying aware of potential errors and implementing preventive measures, clinicians can deliver predictable and lasting outcomes. Modern advancements in endodontic equipment and techniques, many of which are available at DentalKart, make it easier to overcome challenges and refine treatment protocols.

At DentalKart, we’re committed to supporting dentists with high-quality instruments, materials, and resources to enhance clinical practice. By continuously improving skills, staying updated with innovations, and utilizing reliable products, we can elevate patient care and ensure the long-term success of endodontic treatments.

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