Management of calcified canals during root canal treatment. A systematic review of case reports

Introduction

Calcified root canals are a frequent challenge in endodontics. They occur when hard tissue builds up in the canals, leading to partial or complete loss of the canal space. Calcified metamorphosis or pulp canal obliteration is defined as pulpal response to trauma characterized by rapid deposition of hard tissue within the canal space; entire space may appear obliterated radiographically due to extensive deposition, even though some portion of the pulp space remains in histological sections (American Association of Endodontists, 2020). This condition affects approximately 4–24% of teeth requiring root canal treatment (Doranala et al., 2020). They occur when minerals such as calcium salts accumulate within the root canal space, hardening dentin and blocking the passage (Maia et al., 2019; Gürsoy Emek et al., 2022). Calcification can occur either partially or completely, which complicates the process of locating, cleaning, and shaping the canals necessary for effective disinfection and filling (Moradi Majd et al., 2014).

Why do these calcifications occur? Calcifications in root canals may develop from aging, trauma, inflammation, or other pathological factors (Ishak et al., 2020; Heptania, Farahanny & Abidin, 2022; Lewis & Aggarwal, 2023). Dental injuries resulting from substantial force may cause internal bleeding in the pulp cavity and subsequent inflammation which leads to deposition of minerals in the canal. These cases are mostly seen in the anterior teeth of young adults (Chaudhary & Chaudhary, 2022). As age advances, there is an increase in the amount of deposition of secondary dentin, which may contribute to calcification (Freire et al., 2021). Conditions like pulp stones or pulpal sclerosis can also cause calcific material deposition. Also, the presence of deep caries or previous procedures like pulp capping can introduce irritants or materials that promote hard tissue formation (Majid & Elemam, 2015; Yang et al., 2016; Nazar, George & Mathew, 2022).

Locating a calcified root canal during the preparation of the access cavity leads to a variety of challenges, mainly because of limited visibility and variations in the anatomy of the canal (Kumar et al., 2022). Effectively managing these cases is key to achieving successful endodontic outcomes. Failing to address them can lead to persistent infections, treatment failure, and possibly tooth loss (Freire et al., 2021; Gürsoy Emek et al., 2022). Restricted space within the root canal can lead to an increased risk of fracture of both hand and rotary instruments. It also makes it difficult to achieve the required biomechanical preparation (Almohaimede, 2018; Doranala et al., 2020).

Proper management of these cases is crucial for relieving symptoms, ensuring long-term dental health, and improving patient comfort. By using newer techniques, treatment outcomes can be enhanced, and the risk of complications can be reduced.

Treatment of cases with canal obliteration is discussed in many case reports. With the careful use of hand files, chelating agents like ethylenediaminetetraacetic acid (EDTA), and proper irrigation using sodium hypochlorite, it is often possible to successfully negotiate even heavily calcified root canals. The use of dental operating microscopes has been shown to improve accuracy during procedures and may lead to better treatment outcomes (Doranala et al., 2020). Step-back preparation reduces risks like perforation or ledging of the canal. Rotary nickel-titanium (Ni-Ti) systems proved to be valuable in the mechanical shaping of root canal space (Almohaimede, 2018). For successful treatment outcomes, it is essential to plan the treatment meticulously along with the use of cone beam computed tomography, which can provide detailed insights into anatomy such as the extent and location of calcification, and helps in identifying the position of the calcified canal by utilizing 3D print guides (Freire et al., 2021).

Various management techniques are described in the literature for managing these cases but still, it lacks a clear standardized approach (Raghuvanshi, Jain & Kapadia, 2015). Case reports provide great details about techniques for managing included cases, but they are not frequently reviewed systematically. A thorough exploration of these case reports will help to review the most successful techniques which can provide an evidence-based guide for clinicians and also it can point out areas that require further study.

This review aims to summarize techniques mentioned in case reports for managing calcified canals, focusing on effective methods, clinical outcomes, success rates, and common complications. It addresses three key questions:

1. What are the most effective techniques?

2. What are the outcomes and success rates?

3. How are common complications managed?

This review will systematically compile and analyze case reports on managing calcified canals, focusing on methods, outcomes, and associated complications. It aims to provide clinicians with effective strategies, improve treatment outcomes, and highlight research gaps for future advancements in endodontics.

Materials and Methods

A thorough systematic review of case reports was conducted. Research was accredited with PROSPERO database under reference number CRD42023460967 and adhered to guidelines set out by PRISMA 2020, Cochrane Handbook for Systematic Reviews of Interventions, version 5.1.0, and JBI Reviewer’s Manual, 4th Edition (Hilton, 2024; Page et al., 2021).

Results

Study selection

The first electronic database exploration resulted in 5,109 titles from PubMed/Medline, the Cochrane Library, and Directory of Open Access Journals (DOAJ). There were 38,832 items that were referenced twice. Two separate reviewers looked over abstracts and chose 1,271 titles that were relevant; 517 titles were deemed unrelated to the subject and were subsequently deleted. Altogether 126 articles were chosen for complete article assessment after reviewers had examined and discussed them. Manually searching reference lists of chosen studies did not turn up any further publications. Only 34 studies made it through pre-screening, inclusion/exclusion criteria, and PEOS question processing. Data extraction and statistical analysis were performed on 34 studies that were incorporated in the qualitative synthesis (Fig. 1).

Risk of bias assessment

It is presented in Fig. 2.

Consistency in reporting

All studies consistently provided information regarding demographic characteristics, clinical presentation, screening tests used, treatment, post-operative condition, and takeaway lessons. While some reports did not utilize CBCT, they still provided information through detailed clinical and radiographic records. However, it is important to note that CBCT offers more comprehensive three-dimensional information, which may enhance documentation quality in complex cases.

While multiple reports claim they successfully treated calcified canals without CBCT, the inconsistent utilization of this advanced imaging technology may lead to treatment planning bias. CBCT provides a better visualization of canal anatomy and the extent of canal calcification, which can affect treatment decisions and their respective outcomes. The studies which relied on conventional 2D imaging alone may have either had a much more difficult time negotiating the canal or were incomplete assessments. Outcomes amongst these reports may not be entirely verifiable, and the lack of CBCT imaging on occasion may have actually understated the procedural complexity or diagnostic certainty.

Variability in reporting patient history

There is significant variability in the reporting of patient history. Several studies were marked as “Unclear,” indicating that the patient history was either not well-documented or was insufficiently detailed. It is a significant limitation because understanding a patient’s history is important for the interpretation of outcomes of provided treatment.

Lack of reported complications

Out of 34 case reports, none of them reported adverse effects, which is unusual. This suggests that there could be underreporting or an actual lack of adverse events.

Overall appraisal

A total of 27 out of 34 studies were rated as ‘Low’, which is likely due to gaps in reporting, especially regarding patient history and the lack of adverse event documentation. Only seven studies were rated as “Moderate,” which suggests that they had more thorough reporting or a stronger methodological approach.

The overall quality of the studies, indicated by the “Low” appraisal ratings for most, suggests that while they were generally strong in areas like clinical presentation and treatment descriptions, they lacked thorough documentation of patient history and adverse event reporting. These gaps may limit the reliability and applicability of the findings, which highlight the need for more rigorous and comprehensive reporting standards in future research.

Discussion

Managing cases of canal calcifications is one of the most challenging aspects of endodontic treatment due to the obstruction of the canal space, which can affect the success rates. This review analyzes various case reports and highlights key strategies and advanced techniques that have shown promise in overcoming these challenges.

The reports showed that conventional techniques are valuable, but they have notable limitations during the management of these cases. Traditional methods, particularly the use of rigid hand instruments (K files and C+ files) and 2D radiographic imaging, do not often work well when managing the complicated and narrow anatomy found in calcified root canals. These instruments cannot provide great flexibility and tactile sensitivity and expose operator error during these difficult situations. These conventional procedures may increase the risks of procedural errors, including instrument fractures, ledges, transportation, and canal perforations (Doranala et al., 2020; Nabavi, Navabi & Mohammadi, 2022). In addition to that, conventional radiography provides two-dimensional images that may not accurately represent the three-dimensional structure of the canal, which complicates diagnosis and further treatment.

However, advancements in endodontic instruments and techniques have significantly improved the predictability of outcomes, even in complex cases. Many case reports stated that the use of Ni-Ti files in these cases is beneficial with fewer procedural errors (Gopikrishna, Parameswaran & Kandaswamy, 2004; Raghuvanshi, Jain & Kapadia, 2015). Also, the introduction of file systems like continuous rotary systems like Pro-Taper and reciprocating single file system such as Wave One consistently showed improved outcomes while maintaining original canal curvatures. These results may be attributed to its properties like flexibility, shape memory, and superior cutting efficiency (Hegde et al., 2019; Nabavi, Navabi & Mohammadi, 2022).

In cases with apical pathologies, inclusion of calcium hydroxide as an interappointment medicament has been identified as beneficial in promoting healing (Majid & Elemam, 2015; Raghuvanshi, Jain & Kapadia, 2015). However, as case reports suggest, the role of antimicrobial photodynamic therapy (aPDT) is gaining attention as a complementary method in disinfection, particularly in cases involving resistant bacterial strains like Enterococcus faecalis (Hegde et al., 2019).

The use of devices such as dental operating microscopes (DOM) and magnification loupes allowed for improved diagnosis and canal negotiation in these situations. Magnification and radiance delivered by a dental microscope and magnifying loupes allow the operator to locate the orifices of these canals, which are not discernible by the naked eye.

Cone beam computed tomography serves as a powerful adjunct in the management of these cases as it delivers a three-dimensional view of the tooth structure, unlike 2D radiography. It enables accurate visualization of calcifications, canal variations, and anatomical landmarks and also scales down errors in diagnosis and treatment planning (Doranala et al., 2020; Freire et al., 2021; Gürsoy Emek et al., 2022). Out of the reviewed case reports, most of them show success rates of more than 85 percent with the resolution of symptoms and radiographic signs of periapical healing with follow-up ranging from 1 year to 5 years in most of them. The higher success rates reported may be influenced by early diagnosis and the application of modern techniques, highlighting the potential clinical value of these tools (Kiefner et al., 2017).

With time, many clinicians have preferred the use of ultrasonic tips along with dental microscopes, which improve visualization and accuracy during access preparation. This approach enables clinicians to navigate canal calcifications more efficiently. Ultrasonic tips can selectively remove tooth structure and provide better tactile feedback, which improves access to calcified canal systems (Almohaimede, 2018; Takeichi, 2021). This technique helps lower the chances of making errors during procedures, like creating perforations or unnecessary removal of dentin, which are often seen with traditional methods.

Recent advancements like the introduction of 3D print guides along with dynamic navigation systems improved the accuracy and efficiency of navigating and shaping these canals. These methods can be routinely used in calcification cases and are particularly useful in teeth with complex root canal anatomy. As described earlier, CBCT provides three-dimensional visualization of the canal space, which helps in the fabrication of 3D print guides. Static guides are fabricated using CBCT data and 3D surface scans, allowing for preoperative planning and the creation of customized guides that direct the bur along a predefined path. Due to a lack of adjustability, static guides are not able to change their direction in case of any variation in the canal during procedures (Krastl et al., 2016; Gonçalves et al., 2021). With these printed guides, one can precisely navigate canals with minimal risk of canal perforation or transportation.

On the other hand, dynamic navigation systems allow real-time tracking, which further improves success rates in locating and navigating canals (Lara-Mendes et al., 2018, 2019; Tavares et al., 2020).

Dynamic navigation systems can remarkably allow flexibility during the procedure, which reduces the chances of errors. Because of its ability to provide real-time feedback, which helps in the negotiation of canals more accurately, even less experienced clinicians can use it efficiently. However, certain factors like specialized training, high initial investment, and maintenance costs limit its use (Panithini et al., 2023). As technology progresses and costs become more affordable, dynamic navigation systems will probably see more widespread acceptance in the industry. The incorporation of these principles into everyday practice will boost clinician confidence and competence and also improve patient outcomes by decreasing procedural risk and optimizing treatment efficacy (Lewis & Aggarwal, 2023).

One significant limitation of this systematic review is the mini-level of evidence; case reports are descriptive reports that provide rich clinical information. The included reports exhibited extreme heterogeneity across treatment protocols, diagnostic methods (for example, CBCT or 2D radiographs), demographics, experience of the operator, and length of follow-up. The heterogeneity and small sample sizes, and the frequent absence of information regarding aetiology (e.g., trauma vs. age-related), limits the generalizability of the findings. Additionally, the preponderance of favourable outcomes and the absence of complications raise questions of publication bias and selection bias, contextually shifting success rates, which averaged upwards of 85%. Success rates should be interpreted with caution, as there is little guidance in the form of defined meanings for clinical success or common protocols for follow-up.

Significantly, this evaluation found no research that directly compared techniques in a standardized clinical context, thus limiting our ability to assess relative effectiveness. Despite this evaluation showing trends, e.g., the increased use of CBCT technology, dental operating microscopes, ultrasonic devices, and guided endodontics, there was no possibility of conducting any comparative analysis. Quality clinical studies, e.g., Krastl et al. (2016) and Kiefner et al. (2017), reported the higher accuracy of guided navigation systems compared with traditional methods, particularly in the management of severely calcified canals. These external studies are helpful for context and demonstrate the necessity for a consideration of wider clinical evidence to complement case-based evidence.

For these reasons, our results should not be interpreted as definitive, but hypothesis-generating. The data provides preliminary evidence to indicate support for advanced methods but is not robust enough for more generalized recommendations. Future research should focus on prospective, multicenter studies with sufficient sample sizes, standardized outcome measures, and longer-term follow-up. Randomized controlled trials comparing traditional with contemporary approaches (e.g., guided endodontics, dynamic navigation, antimicrobial photodynamic therapy (aPDT), and newer Ni-Ti file systems) are dependent on understanding each method’s relative effectiveness, safety, costs and patient-related outcomes. Future studies should focus on promoting research innovation in the area of chelating agents, imaging and access pathways (e.g., 3D printing and artificial intelligence guided navigation) and encourage and generate a more comprehensive series of clinical guidance to help dentists predictably manage calcified canals.

Conclusions

This systematic review highlights the effectiveness of advanced tools like CBCT, DOM, and Ni-Ti systems. It also emphasizes the need for a comprehensive and individualized approach when managing calcified canals. The incorporation of these technologies into everyday endodontic practice can enhance treatment success, especially in cases where conventional methods are lacking. Also, recognizing the present limitations of case reports such as their heterogeneity and small sample sizes, is important. Future research should focus on standardized treatment protocols, long-term studies, and exploring new technologies to improve the management of calcified canals. Clinicians need to stay updated on these advancements and carefully consider their pros and cons to ensure the best patient care.

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