If you are interested in an endodontic refresher lecture, come and join me next Thursday at the Pacific Dental Conference (PDC 2019). Two and a half hours lecture filled with pictures and videos demonstrating the initial endodontic treatment.
Irrigating the canals…probably the easiest part of providing root canal treatment, yes?
I think I graduated from dental school years and years ago with a deeply instilled fear of perforation, a reluctance to tackle calcified teeth, and anxiety whenever I waited for my obturation film to emerge from the processor. Irrigating the root canal was the breeziest part of treatment, to my memory. I placed an irrigating tip into the canal, made sure it didn’t bind in any place, it was probably hanging around the coronal or mid-root part of the canal, and I pressed the plunger a few times. Presto! Irrigation done. Right. Right?
Reading up on the irrigation literature these past few years has changed my thinking about the importance of irrigation, and it is a procedure that I spend a lot of time on now, probably equalling instrumentation! Many advocate viewing shaping of the canal with rotary instruments as a means to allow irrigants to effectively reach the most apical portion of the root canal. Many would be surprised to see that if our irrigation needle tips are not placed in the apical third of the root canal, we may not be achieving effective irrigation. The easiest way to show this is through a little home made video here, which shows me irrigating in a plastic canal, with a 30 gauge needle, using a fair amount of pressure, equal to about 5 ml/min. The needle tip is held about 3 or 4 millimeters from the “end” of the root canal. Notice how the exchange of irrigant only extends a small distance beyond the end of the needle tip:
Based on some of the literature to date, here are a few suggestions for achieving effective irrigation using a conventional irrigation method:
1. Use a flexible, small gauge irrigation needle, for example, a 30 gauge needle or smaller, that is designed with a closed-end and side-vent (for patient safety). I find that it is quite difficult to use an irrigation needle bigger than a 30 gauge needle, unless the root canal is very large.
2. Prepare the root canal to an adequate apical size and taper such that a small gauge irrigation needle can be placed within 1-2 mm of the working length, or at least in the apical third.
3. Use very gentle finger pressure! A high irrigation flow rate (e.g. high finger pressure) is not required; recent research shows that high pressure/high flow rates does not correlate to “better cleaning”.
4. Activate your irrigants! Use of a sonic or passive ultrasonic tool, such as the EndoActivator by Tulsa, or the Irrisafe file by Clinical Research Dental can make your irrigation more effective. There are many options for agitating your irrigants, and I try to “energize” each irrigant that I use for at least 45-60 seconds per canal, per irrigant, after the majority of the cleaning and shaping has been done.
If you like reading journal articles, here is my recent paper on the “theoretical measured pressure” that the periodontal ligament might feel when we are irrigating root canals. We also have a review paper on irrigation of the apical third in the journal Endodontic Topics, have a read. Send us a message if you can’t find it. Park Shen Haapasalo 2013 irrigation JOE
When I went through my undergraduate dental training, I was taught that MB2 canals in upper molars are there 60-70% of the time. Newer tools and techniques show us that MB2’s are always there whether or not we can get to it. As a matter of fact I tell our endodontic residents at UBC that “if you haven’t found it, you have missed it“.
Here are some pointers on how and where to find the canal that can potentially result in endodontic failure if left untreated, specially if the tooth is necrotic to begin with:
“After about ten years of first appearing on the market, currently Thermafil obturators are completely modified and form an integral part of a complete and sophisticated system of root canal obturation that, when used correctly, can give optimal results. — W. Ben Johnson”
The reported advantages of Thermafil include: shortness of learning curve, speed of clinical application, apical control of fill, conservative enlargement of root canal (when compared to other warm gutta percha compaction techniques), three-dimensional obturation and apical sealing ability, etc.
In my opinion, shorter treatments do not allow for adequate disinfection of the canal system, speed compromises the quality, apical control of fill is nonexistent with this technique, and conservative enlargement of root canal is not always beneficial since some degree of apical enlargement is necessary to allow for proper disinfection by irrigants.
If used correctly (proper size obturator in a single, adequately-instrumented canal and following the manufacturer’s recommendations), 3-D obturation and apical sealing ability are the major advantages of this obturation technique.
Inappropriate case selection for the use of Thermafil obturation technique is demonstrated above. This case shows how Thermafil would give us a false sense of achieving an “optimal” obturation in challenging cases such as this. There was only one obturator used in the canal system that splits into three apically.
As I mentioned in my previous post I Love Sealer Puffs!, extrusion of obturation material into the uncleaned and unshaped portion of the canal system (lateral canals, fins, isthmus, irregular areas, etc.) does not translate into success. The prerequisite for any obturation technique is adequate shaping and cleaning of the entire system, and the only reason for endodontic failure is the presence of micro-organisms.
During re-treatment procedures, removing the gutta-percha dry (if possible) is preferred. Simply because it is less messy. But I often find myself use a bit of C-form (what we call chloroform in the office) specially when I have to negotiate the very last part of the gutta-percha close to the apex. I also use it quite often when I re-treat cases with carrier-based obturation material. And, what a mess that creates!
To get rid of this “soup” of gutta-percha from the access cavity and to continue working in a very clean and controlled environment, alcohol should be used as the next irrigant. It clumps up all the softened gutta-percha to the point that it can easily be rinsed off by water spray or picked off by instruments.
Once the gross removal of gutta-percha from the canals is complete with alternating use of C-form and alcohol, I usually use EDTA as it will continue to clean the remaining of the softened gutta-percha from the canal system.