In our last post, we discussed the process of shaping and cleaning canals during root canal treatment (RCT). But because the field of operation for such a procedure is tiny, the instruments used to accomplish this type of therapy must also be quite small.
Various types of hand and rotary files, and ultrasonic inserts/tips are available to create a glide path, removing calcifications, negotiating twists and turns, and mechanically cleaning canals, leaving smooth walls. Often, hand files are first used to create patency to the radiographic terminus in the apical one-third of a canal, establishing working length, though opinions vary on this.1Advanced Endodontics. Glide Path Management. Available at: https://www.endoruddle.com/jit/detail/84/Glide+Path+Management+Working+Length+Patency. Accessed December 10, 2018.
Many innovations have centered on creating endodontic files that resist breaking inside canals. While high-quality stainless steel files have been developed to offer more flexibility, many endodontists will point to the advent of nickel-titanium files as being a major milestone in dentistry. The material is strong, yet flexible enough to handle canal curvatures without breaking.
Most clinicians likely use a combination of instruments. But they often start with hand files of varying sizes. These include an assortment of color-coded reamers, broaches, and a head-spinning array of files. Of these, the K file is probably the most ubiquitous, followed by the H file.
Rotary versions of hand files are also available for use with engine-driven handpieces. These include rotary and reciprocating handpieces. Both systems are effective at shaping canals, and the choice of which to use is a personal one.
Ultrasonic units have been enjoying increasing popularity for RCT applications in recent years. They implement ultrasonic insert/tips, which come in many sizes and configurations to address various intraoral locations and adapt to dental anatomy. 2Stone R. Inside job. Mentor. 2017;8(10):18–23.
Endodontic Files Innovations
File design improvements are aimed at supporting the concept of three-dimensional endodontics — the ability to address all aspects of canal anatomy. And many are being created to do this with a single file. Newer designs include variations in taper or pitch, said to enhance safety, flexibility and cutting efficiency; the ability to compress or expand within the canal to better hug morphology and reach difficult spots; safety tips to prevent iatrogenic mishaps; and innovations in flute design to enhance canal wall contact while efficiently moving debris coronally.
The genesis of these innovations is said to stem from advancements in imaging. Three-dimensional imaging has revealed that what everyone thought were thorough canal preps when seen with two-dimensional imaging, were actually not so thorough. 3Stone R. Shape-shifters. Mentor. 2016;7(11):21–24.
Endodontic files are tiny, and can easily disappear down patients’ throats. Additionally, irrigants can be caustic, and should not be swallowed. Although dental dams are recommended by the American Association of Endodontists for use in RCT, studies show that more than half of general dentists who perform the procedure do not use them, for a number of reasons, including inconvenience, perceived lack of necessity, and patient refusal. 4Lawson NC, Gilbert GH, Funkhouser E, et al. General dentists’ use of isolation techniques during root canal treatment: from the National Dental Practice-Based Research Network. J Endod. 2015;41:1219–1225. 5Discordance between the presumed standard of care and actual clinical practice: the example of rubber dam use during root canal treatment in the National Dental Practice-Based Research Network. BMJ Open. 2015;5:e009779. 6Hill EE, Rubel BS. Do dental educators need to improve their approach to teaching rubber dam use? J Dent Educ. 2008;72:1177–1181.
Instead of simply relying on the use of cotton rolls for isolation as a way to avoid using dental dams, some clinicians are employing systems such as Isolite for RCT procedures. By using Isolite, clinicians can shield their patients’ throats, while also benefitting from continuous suction, retraction, a patient-friendly bite block, and illumination. Such a system offers protection in the absence of a dental dam — for whatever reason.