What Dentists Learn At Our Endodontic Workshop

• The superior utilization of stainless steel reamers compared to K-files
• The superior use of relieved stainless steel reamers compared to K-files
• The use of relieved stainless steel relieved reamers in a 30o handpiece oscillating at?3000-4000 cycles per minute.
• That using these reamers in the 30o oscillating handpiece virtually eliminates instrument separation.
• That reamers that are immune to breakage can be applied aggressively against all the canal walls cleansing them better than the centered shaping of rotary NiTi.
• That limiting high frequency oscillations to such short arcs of motional also prevents the?instruments from distorting the canals.
• That the instruments can be used multiple times because they will not break.
• That the high frequency of oscillations activates the irrigants and along with the application of?the reamers against all the canal walls results in three-dimensional debridement.
• The 02 tapered stainless steel relieved reamers provide more room for the irrigants that allow?
• ?more debris to go into solution and less likely to be impacted apically with loss of length.
• The bidirectional spiral cement applicator coats the canal walls without driving the cement?over the apex prior to placing the profited gutta percha point.
• A single well-coated point placed into a canal already coated with sealer produces a three-dimensional seal without the need for additional points.

What are?the main points that the attendees of the workshop take away?

• That systems are available that virtually do away with the concerns of instrument separation.
• That such systems are motor-driven minimizing hand fatigue while reducing procedural time requirements.
• That instruments invulnerable to separation can be vigorously applied against all the canal walls giving them the ability to debride oval canals and thin isthmuses.
• That short arcs of motion even at high frequency eliminate canal distortions when using the stainless steel relieved reamers.
• That relieved stainless steel reamers are far less likely to impact debris apically compared to?K-files.
• That single point room temperature obturation using the techniques taught in this workshop?result in three-dimensional obturation.
• That the cost of oscillating instrumentation is a small fraction of the cost of rotary NiTi.

To focus on one of the main attributes of 30o oscillating reamers, namely the prevention of instrument separation, let’s discuss the series of events that is likely to take place when the dentist breaks an instrument in the canal.

• First we try to remove it. Removing any separated instrument is rarely an easy task. If it separates around a curve, the attempts to remove it can take a lot of time and potentially sacrifice a good amount of supportive dentin. It should be noted that many of the systems developed to remove separated instruments are themselves quite expensive without producing predictable successful results
• If the instrument cannot be removed attempts are made to negotiate around it. This can also take a great deal of time and inadvertently worsen the situation by causing perforations and an even greater loss of tooth structure.
• If the dentist cannot negotiate around the separated instrument, he/she may leave it as it is and hope for the best, elect to have apical surgery or to extract and place an implant.

We are obviously better off if we do not have to confront these decisions by not breaking instruments in the first place. Yet, rotary remains quite popular despite this undesirable shortcoming for the following reasons:

• They do away with a good portion of hand fatigue when compared to the traditional manual use of K-files in canal preparations.
• Engine-driven they often shorten the procedural time requirements making the dentist more productive and profitable. This positive comparison is pretty much always compared to the traditional manual canal preparations.
• The rotary NiTi instruments designed as reamers are less likely to apically impact debris reducing the chances of loss of length. Again this favorable comparison results from being compared to the manual use of K-files.

The reasons cited above, all have a common thread. They are improvements most appreciated when compared to K-files used manually, the system most dentists employed exclusively prior to the introduction of rotary NiTi. The implication espoused by rotary NiTi advocates is that stainless steel incorporating the design of a K-file and used manually represents the sole way they can function and one should not expect any further innovations in their usage, a conclusion that is not supported by reality.

If one is going to compare the latest iteration of rotary instruments to stainless steel, it makes sense that the comparison should be against the latest version of stainless steel, namely engine-driven oscillating relieved twisted reamers confined to 30o arcs of motion at a frequency of 3000-4000 cycles per minute. This comparison nullifies the advantages of reduced hand fatigue, greater productivity and impacted debris attributed to rotary NiTi while adding the advantages of the elimination of instrument separation and canal distortion, something associated with the traditional use of K-files.?

To support the positive claims for superior debridement, cross-sections of oval canals show no signs of residual tissue left in the canals. Is this data valid? Are cross sections showing no signs of residual debris left in the buccal and lingual extensions of oval canal after debridement with the oscillating reamers convincing? If not, why not? When a video shows complete removal of simulated pulp tissue in thin bucco-lingual isthmuses of 3D printed teeth, is it reasonable data to infer that the instruments are effective? Again, if not why not? Depending upon the agenda of those making these judgments it is or it isn’t. For me, the most direct way to gain trust when addressing the dental community is by providing an environment where the dentists can test the claims made for the approach we advocate, namely endoodontic workshops.?

Almost as important as the prevention of rotary instrument separation is the consequence of the steps needed to prevent it, namely the precaution to use them in the least resistant centered position, one of several precautions rotary advocates recommend to reduce the incidence of separation. Indeed, the most telltale evidence we have that rotary NiTi has shifted the emphasis from canal debridement to keeping the instruments intact is the emphasis that is placed on keeping the NiTi instruments confined to the widest central portion of the canals. In the days before rotary NiTi, endodontists knew they needed to cleanse the canals in three-dimensions. Hedstroms were invented to lean against the canal walls and scrape them clean by implementing the pull stroke. This process took effort, a good deal of hand fatigue, but it was implemented because endodontists understood that the primary goal of instrumentation is to clean the canals as well as possible.

Today with the use of rotary often unable to thoroughly cleanse oval canals lest their chances of breakage increase significantly, there is no compensating procedure suggested for rotary’s deficiencies in this aspect of instrumentation. Yes, the rotary advocates could suggest the supplemental use of Hedstroms, but introducing a manual system to compensate for the shortcomings of rotary goes against the branding of rotary NiTi as a paradigm improvement. So, the argument advanced today for this particular shortcoming of rotary’s is that it is no shortcoming at all. Rather it did its job in creating a greater tapered undistorted funnel the length of the canal and full debridement is now the job of any of the new and very expensive laser activated irrigation systems.?

What cannot be solved by rotary is now defined as outside of rotary’s responsibilities and is laid at the feet of ever more expense irrigation systems to compensate for the inadequate debridement that by the newly applied definition is not a goal rotary is even supposed to address. From a marketing point of view, rotary is best sold on the basis of convenience.

• Less hand fatigue always being compared to the manual use of K-files
• And now with the more conservative rotary preparations that are in vogue today, a reduction in time, less expense and and a reduced chance of separating an instrument.

As the song goes, you’ve got to accentuate the positive, eliminate the negative, latch on to the affirmative, don’t mess with Mr. In-between.

Today, the standard for excellence is the white line to the apex, a recognition of cleansing and obturation that gives minimal information about what is happening in the wider bucco-lingual plane of oval canals, an anatomic configuration that the majority of the canals have. With the recognition that convenience is rotary’s strong suit, the manufacturers are developing rotary instruments that create a glide path further reducing hand fatigue and developing instruments that in what appears to be simple anatomy don’t even require the creation of a glide path. All these innovations are most safely used if they are not extended beyond their centered positioning.

From a strictly convenience point of view, in those cases that offer minimum resistance nothing is quicker than 1 or 2 rotary instruments. The situations that conform to this rapid and easy use may make up a good portion of the teeth the general dentist elects to do. The more complicated anatomy does not offer the same benefits of minimal hand fatigue and less time with no concerns for breakage. If the dentist wants to expand his/her abilities it will pay for them to adopt systems that are inherently safer as the anatomy becomes more complex. Nevertheless, it is the above conditions with little consideration given to the state of debridement beyond a white line to the apex as seen in periapical x-rays that determines the value many dentists give to the system they are employing.

To have an impact with an oscillating system the dentist should know that this system devoid of separations has the increased ability to cleanse in three dimensions and that is an important factor in long range success, something they may be interested in, considering many of the teeth will be restored by the same dentist. If he/she realizes that superior debridement is possible while completely avoiding the possibility of instrument separation, this could be a deciding factor in using the oscillating system.

No breakage, better cleansing resulting from internal routing and targeted instrumentation of a 30o oscillating system as compared to the centered shaping of rotary NiTi. Reusability is also a plus with systems virtually immune to breakage. It is also worth stating that the reduction in hand fatigue is reduced even more with the 30o oscillating systems. The dentist should understand that the rotary experience in so-called “simple” anatomy is an entirely different experience as the anatomy becomes more complex. With ever greater pulpal complexity, safety is increasingly based on keeping the arcs of motion confined to levels that don’t exceed 45o thereby eliminating separations and preventing the instruments from introducing distortions.

Rotary does not provide for a one system fits all situations solution. A dentist can be sold on a system dealing with simple anatomy only to find severe limitations as the canal anatomy becomes more complex. The real deficiencies reside in the studies that clearly show inadequate debridement of oval canal?when using rotary systems. Despite these deficiencies, the dentist generally does not react negatively to this information if the mesio-distal periapical x-ray looks good. That is a defect in the educational system that is not unexpected considering the students learned the systems supplied by the rotary manufacturers. It is unlikely that the education the students receive is going to point out the deficiencies in the system they are directed to use. Indoctrination rather than education. The educational system produces students unappreciative of the essential goals of instrumentation and then takes advantage of that inadequate education to foist upon them techniques that don’t address the core issues of instrumentation.

It’s a bit of a vicious cycle, something that routinely appears when money is the arbiter of what takes center stage.

Regards, Barry