New strategies and technologies may help to improve the success rate of calcified root canal negotiation. Challenges during negotiation in canal spaces that are unobstructed from the canal orifice to the apical foramen are minimal and both negotiation and instrumentation are typically uneventful.
With aging, hard tissue gradually forms along the root canal walls. Further, tooth wear, operative procedures, vital pulp treatment, and regenerative endodontic procedures may encourage the formation of hard tissue in the pulp canal space. However, dental trauma, auto-transplantation, and orthodontic treatment can accelerate this deposition and cause narrowing or closure of the root canal known as root canal calcification. There are two types of calcification: partial calcification, in which the pulp chamber is occluded and the canal constricted but identifiable; and complete calcification, in which the pulp chamber and canal are hardly or not identifiable.
In a study, published in the Journal of Clinical Medicine, investigators reviewed the existing methods for navigating and managing calcified root canals. Performing procedures to clear the residual root canal may increase the risk of ledging, false canal creation, perforation, and tooth weakening.
Although conventional endodontic therapy on root canals with severe calcification may be challenging and increase the risk of procedural issues, specialized instruments and dedicated negotiation concepts have been developed. Study investigators noted that conventional techniques, operating microscopes with coaxial illumination, magnification, and stereoscopic depth perception and high-resolution cone-beam computed tomography (CBCT) can all be used to negotiate to the apical third of calcified root canals.
The investigators indicated that radiographs can aid clinicians in diagnosing and evaluating factors involved in root canal calcification. However, radiographs that show clear canals can be difficult to navigate with endodontic instruments as a result of inaccuracies in the true clinical size of the canals.
Conversely, CBCT has demonstrated its effectiveness at identifying root canal calcification in prior research. This method has been shown to aid clinicians in locating root canals, creating stents for precise alignment, and depth control of the bur. Compared with CBCT, endodontists improperly identified 40% of root canals. The investigators suggested that CBCT may allow for the avoidance of unnecessary stents. Still, they noted that the choice of CBCT view size could affect image resolution.
During root canal negotiation, small files are used for initial pathfinding; however, these tools can become damaged or break without successfully navigating the canal space. The investigators proposed interchangeably using modified size 8 and 10 K-files—with diagonally sliced tips—to minimize vertical pressure, enhance penetration potential, and increase the effectiveness of calcified root canal traversal. It is advised to replace the tools prior to the occurrence of damage.
In addition, pathfinding instruments with work-hardened or fiber-reinforced stainless-steel alloy have recently been introduced to improve root canal negotiation. These tools—including the Canal Pathfinder, Pathfinder CS, C +Files, D-finder files—incorporate modified tips, tapers, and cross-sectional designs to streamline penetration of the calcified or fibrotic structures. Furthermore, long-shafted burs may aid in deep troughing along the axis of the obliterated roots, facilitate the identification of calcified canal orifices, and enhance clinicians' visibility during the procedures.
No conflicts of interest were disclosed.
