Single-use rotary files

Oct. 1, 2003
This past summer, we had the opportunity to attend and lecture at the "Roots Summit" in Anaheim. During the meeting, there was a discernible buzz about where endodontics is headed.

Dr. Dr. Ken Koch and Dr. Dennis Brave

This past summer, we had the opportunity to attend and lecture at the "Roots Summit" in Anaheim. During the meeting, there was a discernible buzz about where endodontics is headed. Several speakers addressed the topic of asepsis and single-use items in endodontics. In our opinion, it is about time that endodontics became as dedicated to single-use items as other aspects of dentistry. We are incredulous that many patients will pay more than $1,000 for a root canal, yet they do not receive the dignity of having their own rotary instruments. How would you like to have an implant that previously was in someone else's mouth? We don't think so! Look for the introduction of more single-use endodontic items in the near future. This is a concept that you cannot argue against.

Q: What has been the major hindrance to the single use of nickel titanium rotary files?

A: Easy answer ... money. Most clinicians feel rotary files are too highly priced and consequently, want to use them multiple times. We firmly believe that rotary file prices will decrease. In fact, we believe dental companies can make better files at a lower price, if they seriously want to do so. It is all about margin and price points. Time will tell.

Q: What happens if you use a file multiple times?

A: There are three significant issues with the multiple use of rotary files. The first concern about multiple use is sterilization. Did your staff properly sterilize the file or did they merely wipe it down? What's the consequence of doing neither procedure? Think how many times you have seen a sponge in a dental office with files sticking out. Would you like to have those files in your mouth? We don't think so. The real concern about sterilization is whether it actually occurs.

The second issue is where your staff sterilize the files, but, during ultrasonic cleaning, the rotary files come in contact with some stainless steel items. The result of this interaction (between the nickel titanium file and the stainless steel) has a deleterious effect on the strength of the NiTi rotary files. These rotary files are now, as a result of a detrimental galvanic action, more prone to separation. NiTi rotary files must be kept separate from stainless steel items while in the ultrasonic bath.

The third issue — and a major concern — is the accumulation of cyclic or metal fatigue. Cyclic fatigue is one of the two major causes of instrument separation. The other leading cause is excessive torque.

While you can see evidence of excessive torque by an unwinding of a rotary file, there is no ability to see cyclic fatigue. Cyclic fatigue is insidious. An instrument may "look" fine, but the next time it is placed into a canal, it may break.

Therefore, the only way to control cyclic fatigue is by monitoring the use of the file. The inability to monitor cyclic fatigue is what creates a tremendous advantage to the single use of rotary files. This concept of single use applies to any of the rotary systems currently in the marketplace. Remember, while there are torque-control engines, a cyclic fatigue control engine does not exist. Cyclic fatigue is only controlled through limited use of a rotary file.

The idea of single use or truly disposable rotary files is a new concept that requires serious consideration. This is why it is so important for all practitioners to keep an open mind both clinically and in academics. This means exposing your mind to true endodontic education, not merely indoctrination.

The next few years will see the introduction of many new concepts to endodontics. There will be so many new products and techniques coming together that it will be like an endodontic "Perfect Storm." Consequently, it is paramount that everyone evaluate these new ideas with an open mind, not a closed one. Think through the concepts and consider the techniques.

Let us never forget that the end user - beneficiary — of all our education — is the patient. Rest assured that Real World Endo will help you navigate these new challenges by offering "Just the Facts, Nothing but the Facts."

Dr. Dennis Brave is a diplomate of the American Board of Endodontics and was the senior managing partner of a group specialty practice for 27 years. Dr. Kenneth Koch is the founder and past director of the new program in postdoctoral endodontics at the Harvard School of Dental Medicine. Drs. Koch and Brave together are Real World Endo, an endodontic education company. They can be reached at (866) RWE-ENDO, or visit their Web site at

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