07 January 2022

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Guided endodontics for treatment calcified canals

Lara Figini

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The American Association of Endodontists classifies endodontic treatment of obliterated canals as a high level of difficulty. The individualization and shaping of the calcified root canal represent a challenge to manage even when using an operating microscope. Potential procedural errors include overextension of the access cavity, iatrogenic perforation, separation of shaping files, and deviation of the root canal from the original path, all of which prevent the clinician from achieving the correct working length. To improve treatment planning and simplify the technical procedure, digital technology can be helpfull. Superimposing images on a patient's Cone Beam Computed Tomography (CBCT) enables the design of a three-dimensional (3D) guide. Similar to the 3D planning of dental implants, even in guided endodontics the correct rotation, angulation and positioning of the drill can be virtually predefined. This method allows the clinician to locate calcified root canals while minimizing procedural complications.

Materials and methods
In a clinical study, published on Journal of Endodontics, February 2021, the authors illustrated clinical cases in which severely calcified canals were treated using a custom three-dimensional (3D) guide designed by overlaying a conebeam computed tomographic scan with an intraoral scan of the patient. This 3D guide allows the clinician to gain direct access to the obliterated root canal. The study presented cases of seven adult patients (aged 27 to 53 years) with a previous history of dental trauma, treated between 2015 and 2017.

Results
None of the teeth responded positively to thermal or electrical tests, although the sensitivity to palpation was observed in 4 cases and to percussion in 2 cases. Radiographic examination, which included a periapical radiograph (Kodak RVG 6100; Carestream Health, Rochester, NY) and a selective CBCT scan (Newtom 5GXL; Newtom, Verona, Italy), revealed an apical lesion in 6 of the 7 teeth and PCO advanced in all teeth. Surgical planning software (BlueskyPlan, Libertyville, IL) was used to design the 3D guides which were then printed and proper fit occurred. The endodontic treatment was then carried out under isolation with a rubber dam, and the design of the access cavity was carried out. Working length was determined using an apex locator (Raypex 5; VDW, Munich, Germany) and digital radiography. The root canal shaping was performed using the ProTaper Next system (Dentsply Maillefer, Baillagues, Switzerland) or WaveOne Gold instruments (Dentsply Maillefer) under irrigation with 5.25% sodium hypochlorite. In 2 teeth, calcium hydroxide was left for 3 weeks as there was uncontrollable suppuration in the first session. All root canals were sealed with hot gutta-percha using the continuous wave technique. No patient reported discomfort on percussion or palpation 1 year after treatment if periapical healing was evident.

Conclusions
From the data of this study, which must be confirmed in other similar studies, it can be concluded that guided endodontics can be considered a safe and fast approach and can be considered a predictable technique for the localization of calcified canals, thus minimizing complications .

Clinical implications
Guided endodontics guarantees direct access to the canal, preserving greater tooth structure and avoiding associated iatrogenic accidents.

For additional information: Guided Endodontics for Managing Severely Calcified Canals