10 Common Endo Mistakes (And How to Fix Them) by Dr. Reid Pullen

Dentaltown Magazine  

by Dr. Reid Pullen

I practiced as a general dentist for five years and struggled with root canal treatment before entering an endodontic residency. I was inefficient, had poor technique and was lucky to obtain a good result. I cringe when I think about those early patients and the probable failure. But every problem has a silver lining: Even though I struggled with failure, I also learned a lot about success and augmented my training with educational journals, workshops, books and classes. Over time the keys of the endodontic kingdom started to unlock the beauty of root canal treatment and I became fascinated with improving my endodontic care.

Now, I want to help dentists avoid common maladies and perform effective, efficient and excellent endodontic treatment on simple and medium-difficult cases. Here are 10 solutions to mistakes that I routinely see when general dentists perform root canal treatment.

1. Incorrect armamentarium

I remember working in an office near Los Angeles as a general dentist. I was performing a molar root canal and asked for another #10K file. The assistant said, “I’m sorry, we’re all out of those.” That moment never left me. I am a big proponent of having the correct tools for the job. How can you perform quality root canal treatment without the right instruments?

So, what are the intangibles?

1. 21mm, 25mm and 31mm #6–80 K hand files. Buy one pack of the larger files #50–80 in each length. Make sure you have plenty of #6, #8 and #10K files. These are the files that you will use the most. Use these for only one case and then throw them away.
2. Electronic apex locator. These devices are extremely accurate in electronically measuring working length and save you treatment time. I love the ProMark Apex locator from Dentsply Sirona.
3. New shaping files with an endodontic motor. I love the ProTaper Gold and WaveOne Gold shaping systems. These shaping systems allow me to efficiently shape the canals and achieve a very predictable, beautiful shape.
4. Obturation systems such as GuttaCore or GuttaSmart. These systems allow you to perform predictable 3D obturation.

2. No rubber dam

It’s imperative to use a rubber dam for every endodontic case. It’s the standard of care. The rubber dam prevents microbes in the oral cavity from contaminating the root canal system. It retracts the lip, cheek and tongue and allows you to focus on the treatment tooth. It also keeps the patient safe and prevents sodium hypochlorite and 17% EDTA from running into the oral cavity. Also, if you drop a file into the mouth, it falls into the rubber dam, not down the throat.

3. Missed canals

Accessing and locating all of the canals is one of the general dentist’s main concerns when performing endodontic treatment. One question I often hear when I lecture is, “How do I find all the canals?” The answer is vision and experience. Let’s start with high-magnification loupes and a bright light source: You can treat what you can see. Secondly, assume all molars are guilty of four canals until proven innocent of three. Third, take high-quality straight and angled periapical radiographs and a bitewing. The bitewing helps you determine how calcified the pulp chamber may be or if a large pulp stone is present. Use CBCT if you have one. Preplan your access by viewing the axial slices. Look for extra anatomy and refer back as needed during access.

4. Non-negotiation to patency

This is one of the most important pillars of endodontics: If you can’t get to the end of the canal, you can’t be sure you cleaned it all. If any part of an infected canal is not clean, there could be potential for reinfection. After coronal flare with the ProTaper Gold SX, I take a #10K 25mm file, dip the tip into RC Prep and insert it into the canal until it hits resistance. I then reciprocate it gently through the resistance and continue to advance down the canal until I either hit a “brick wall” or pop out the foramen.

On simple cases, the #10K file will exit out of the foramen (patency) and you’ll sometimes feel a little pop or give as it enters through the minor constriction, then out into the periapical tissues. If the #10K hits a “brick wall,” then most likely there is a slight apical curve. I remove the #10 file and select a #8K 25mm file and create a 45-degree apical bend with my fingernails. I then place the file back in the canal down to the block and take the file on a walk around the cul-de-sac of the apex.

By slightly lifting up on the file, then rotating the curved part of the file around the apex, I can usually find where the canal curves and subsequently negotiate to patency. One trick to make this process easier is to first shape the coronal and middle thirds of the canal with a ProTaper Gold Shaper 1 (purple) file. This opens the coronal/middle thirds and allows the #10K file to easily advance down to the apex. Shape only the coronal/middle thirds and shape short of where the #10K extended.

5. Inaccurate working length

Everything follows negotiation to patency because electronic apex locators work predictably off patency (the file exiting the canal foramen 0.5mm into the periapical tissues). But many dentists first fail to negotiate the entire length of the root, then become lost inside the tooth and cannot obtain an accurate working length. The most efficient way to do this is to first negotiate to patency and then use the electronic apex locator.

I love the ProMark and Root ZX II because they provide a very accurate working length. I recommend leaving the lip clip on through the appointment and confirming your working length during shaping.

6. Shaping without an open glide path

In my opinion, the three pillars of endodontic treatment are negotiation to patency, accurate working length and open glide path. Many dentists skip endodontic treatment steps and fail to obtain an open glide path, then wonder why the file separated or why they ledged the canal. It’s imperative that you have a slip-and-slide glide path for the shaping file to advance down the root effectively and safely. Creating an open glide path is fairly easy because of advances in file metallurgy allow the newer glide path shaping files to effortlessly cut an open glide path. I like to first get a loose #10K file to working length, then run a ProGlider or WaveOne Gold Glider nickel titanium file down the canal to create a nice open glide path.

7. Quick shaping

A lot of dentists I work with in my hands-on workshops just barely shape the apex, then wonder why the gutta percha cone is 2mm short. I call it “pecking the apex on the cheek.” To achieve deep apical shape, you need to “make out with the apex.” Don’t just touch and peck the apex (established working length) one time with the last shaping file; instead, gently shape the apex three to four times. Use a gentle up/down motion three to four times to working length, which should provide deep apical shape and help aid the cleaning of the apical third.

In my hands, the WaveOne Gold and ProTaper Gold shaping systems create incredibly efficient and effective shapes and give me excellent results. I’ve used these files in thousands of my own cases and have been astounded with the results. The safety is astonishing, and I can’t remember the last time I separated either of those files.

8. Inadequate disinfection

It’s so important to use sodium hypochlorite throughout the entire root canal procedure. Never shape without sodium hypochlorite in the canals. I like to use 5–6% sodium hypochlorite. I also believe that enhanced disinfection provides for cleaner canals. The GentleWave system uses multisonic sound waves to power-wash the canal system. It is an excellent cleaning system, but not always feasible for general dentists. The next-best enhanced disinfection tool is the EndoActivator, a cordless handpiece that sonically activates the bleach and QMix or 17% EDTA in the canal system. It is extremely safe and easy to use. I recommend using the EndoActivator for one minute in each canal with sodium hypochlorite, then sucking out the bleach and placing QMix (EDTA/chlorhexidine) and using it for another 30 seconds per canal to remove the smear layer.

9. No cone-fit or size-verifier-fit radiographs

Once cleaning and shaping are complete, the next step is to cone-fit and take a radiograph. This step is important and is often skipped. Select the correct gutta-percha cone that matches the shaping system and try it in the canal. Crimp the cone with cotton pliers at the reference point, then check the measurement: Is it right at your working length, short or long? If it’s short, you may need to reshape. If it’s long, trim the end of the cone with scissors.

Once the cone fits to the established working length, it’s time to take a cone-fit radiograph (I often take a straight and an angled PA). The same is true if you’re using GuttaCore; you must make sure the size verifiers fit to within 0.5mm of working length, then take a size-verifier-fit radiograph. This is the last step before you place a material into a patient’s tooth. Let’s make sure we have an excellent fit before sealing the root system forever.

10. Poor obturation outcome

In my experience, many dentists perform single-cone obturation with or without calcium silicate sealers. It’s not recommended to perform single-cone obturation without a calcium silicate sealer like BC Sealer. I used calcium silicate-type sealers for a few years in my practice and didn’t get the success that I had with warm vertical obturation using Pulp Canal Sealer or ThermaSeal Plus Ribbon Sealer. I’ve gone back these past three years to warm vertical obturation using the newer GuttaSmart fill system, and I now obtain excellent 3D fills with a sealed apex and anecdotally much better success. We must first dry the canals well with paper points, then butter the apical third of the gutta-percha cones with sealer and place into the canal and down to working length. I then burn off the coronal/middle thirds of the gutta-percha cone, leaving an apical plug of gutta-percha. I gently compress the apical plug with a small plugger, then backfill the canal with gutta-percha. There are a few obturation systems in the market that have cordless heat tips and backfill handpieces such as Elements IC from Kerr, but my favorite is the GuttaSmart by Dentsply Sirona.


In the game of endodontics, it’s imperative that we play by the rules of the root canal system. It all starts with the right endodontic armamentarium and a root canal game plan. If you don’t have the right tools for the job, don’t start the job. The rubber dam is one of the key tools and needs to be placed for every root canal treatment.

Once treatment begins, clinicians must have good knowledge of the anatomy and configuration of the different root canal systems and visualize what they’re doing with high-magnification loupes and a bright light source. This is key to proper access and locating the canals. Once all canals have been located and a coronal flare is complete, negotiate to patency with a 25mm #8 or #10K file. Obtain an accurate working length and an open glide path. Shape the entire canal well and disinfect appropriately, taking the time to obtain the cleanest canals possible. Finally, obturate. Fill those canals and provide a long-lasting hermetic seal. Lock away any microbes that may still be in the dentinal tubules from the outside world (periapical tissues). Remember, don’t just get your root canals done, get your root canals won.

Author Bio
Author Dr. Reid Pullen graduated from USC Dental School in 1999, then was stationed in Landstuhl, Germany, for three years with the U.S. Army. He completed a one-year Advanced General Dentistry residency, then practiced general dentistry in Yorba Linda, California, before doing an endodontic residency at the Long Beach, California, VA. Board-certified in endodontics, Pullen has owned a private practice in Brea, California, since 2007, teaches 2-Day Root Camp Boot Camp live-instruction classes and runs Root Canal Academy. Email: reidpullen@rootcanalacademy.com
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