Shaping and Cleaning for Successful Root Canal Treatment

By Rebecca Stone January 22, 2019

In today’s climate of minimally invasive dentistry, root canal treatment (RCT) makes sense. Instead of extractions and implant placements, the patient’s own tooth can be strengthened and left in place. To accomplish this, any infected tissue in the canals must be removed, and the canal walls shaped, cleaned and disinfected.

Creating a Smooth Contour

Ultrasonic, rotary or hand files — or a combination of these — are used to shape and smooth canal walls by eliminating infected tissue, calcifications, and other irregularities. Whichever approach is used, the smoother the resulting structure, the better. 1Stone R. Inside job. Mentor. 2017;8(10):18–23.

During the shaping process, debris accumulates in the canal that must be removed. Mechanical instrumentation can only take out so much. Yet, thorough cleaning and disinfection of canals are paramount to success. This is where irrigants come in.

Cleaning and Disinfecting

Irrigants provide lubrication for instruments but they are also bacterial agents used to help cleanse canals, dissolving or flushing out debris. Such agents typically include sodium hypochlorite, chlorehexidine gluconate, and ethylenediaminetetraacetic acid. But the ticket to this particular kind of root canal nirvana comes courtesy of irrigant agitation. 2Stone R. Inside job. Mentor. 2017;8(10):18–23.

There are numerous irrigation techniques, including an apical negative pressure system. This technology pulls (rather than pushes) irrigant down to the apical third, safely delivering it to working length while minimizing the risk of blowing through the apex.

When ultrasonic energy is used, agitation and acoustic streaming (rapid fluid movement) help to drive the disinfecting solutions into the far reaches of canal structure that would otherwise go untouched. 3Stone R. Inside job. Mentor. 2017;8(10):18–23.

One of the best-known techniques used to agitate irrigants is passive ultrasonic irrigation (PUI), which is performed without simultaneous instrumentation. It involves placing the irrigant via a syringe, and then agitating it via a noncutting, oscillating file tip or a smooth wire. This results in acoustic streaming and cavitation to enhance the cleansing reach of the irrigant. 4Stone R. Inside job. Mentor. 2017;8(10):18–23.5Mozo S, Llena C, Forner L. Review of ultrasonic irrigation in endodontics: increasing action of irrigating solutions. Med Oral Patol Oral Cir Bucal. 2012;17:e512–e516.6Nielsen BA, Baumgartner JC. Comparison of the EndoVac System to needle irrigation of root canals. Available at: Accessed December 5, 2018.

Isolation During RCT

Because one of the main goals of root canal treatment is to disinfect canals, tooth isolation during root canal treatment is necessary to minimize the risk of contamination from oral bacteria present in saliva. The American Association of Endodontists recently reaffirmed its position that the use of rubber dams is the standard of practice due to its function as a barrier. Dental dams also improve visualization and provide a measure of safety against aspiration of tiny files or caustic irrigants. 7American Association of Endodontists. Dental Dams: AAE Position Statement. Available at: Accessed December 5, 2018.

Yet, countless studies show that rubber dams are used by less than 50% of general dentists when performing RCT. A number of reasons for this are cited, ranging from inconvenience to patient refusal. 8Madarati AA. Why dentists don’t use rubber dam during endodontics and how to promote its usage? BMC Oral Health. 2016;16:24.9Gilbert GH, Riley JL, Eleazer PD, Benjamin PL, Funkhouser E; National Dental PBRN Collaborative Group. Discordance 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. 10Anabtawi MF, Gilbert GH, Bauer MR, et al. Rubber dam use during root canal treatment: findings from The Dental Practice-Based Research Network. J Am Dent Assoc. 2013;144:179–186. 11Hill EE, Rubel BS. Do dental educators need to improve their approach to teaching rubber dam use? J Dent Edu. 2008;72:1177–1181.

But rather than completely operating without a net, some are reported to at least use other measures such as cotton rolls and dry angles. Still others report using Isolite as a sole means of isolation or in combination with other methods. 12Gilbert GH, Williams D, Korelitz JJ, et al. Purpose, structure, and function of the United States National Dental Practice-Based Research Network. J Dent. 2013;41:1051–1059.

The Isolite system provides improved retraction, a bite block and illumination. But most importantly, it provides throat protection against instrument or irrigant aspiration.

When it comes to root canal treatment, isolation of the tooth can help ensure success. Isolation of the throat can save a life.