A study that tells us what "they" want us to hear

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A study that tells us what "they" want us to hear

Postby BarryMusikant on Fri Jun 04, 2010 4:57 pm

The May 2010 issue of the JOE includes an article titled, Impact of a Retained Instrument on Treatment Outcome: A Systematic Review and meta-analysis authored by Piyanee Panitvisai et al.

The authors concluded in the abstract that “on the basis of the current best available evidence, the prognosis for endodontic treatment when a fractured instrument fragment is left with a root canal is not significantly reduced.” Yet under the discussion, the authors state that “outcome of endodontic treatment is related to effective disinfection of the root canal system and prevention of recontamination. An instrument fragmentg in itself is rarely the direct cause of the problem; it does, however, limit access to the aical part of the canal, compromising disinfection and obturation. The clinical situation (existence of periapical lesion), stage of canal preparation when instrument fracture occurred (canal infection), canal anatomy, fragment position, and type of fractured instrument can significantly influence prognosis and the approach to management.”

The authors concluded that despite the problems associated with fractured instruments blocking access to the apex that the prognosis of a tooth with a fractured instrument within a root canal is not significantly reduced. “The prognosis is lower if periapical pathology is present at the time of treatment, but only to the extent that effective disinfection is compromised. This conclusion, however, might not be fully applicable in general practice conditions because data in this review were derived from specialist practices and well-controlled university clinic.”

Having been an endodontist for close to 40 years I never remember reading an article that discussed the breakage of K-files, the instruments typically used for cleaning and shaping canals. The reasons I believe are obvious. If they did break we knew exactly why they broke and were then able to avoid future breakage. NiTi is a completely different animal. It can break unpredictably despite our most cautious efforts. They can break after a single usage in a host of situations that require a perfectly shaped glide path as a precondition for safe usage. The incidence of breakage has been a part of rotary NiTi since its inception and denying or using research to mitigate the effects is to my mind simply marketing in the guise of research.

The repetitive use of stainless steel files was never an issue either. It took the vulnerability of rotary NiTi to foster the single use concept. An  advocate of rotary NiTi might say all instruments should only be used once and discarded even though all other instruments can be used multiple times without concerns for breakage. To take our mind off that glaring weakness, that is never the reason given for single usage. Rather, we are concerned about prions and mad cow disease. Fine. If this a serious concern, every instrument that ever touches blood must be used once and discarded, a notion that will send medical costs further thru the roof.

Here we had a study clearly stating the blockage of an already infected canal with a broken instrument can adversely affect the prognosis. Yet, in the hands of a specialist or in the controlled environoment of a teaching institute, there is barely a ripple in the prognosis. It would be far more constructive, imo, to teach systems that are designed not to break while shaping canals thoroughly without distortion. Naturally, I vote for what we created, but greater benefits for any system stem from a discussion of what works most favorably, rather than apologizing for a systems defects.

Always happy to hear other points of view.

Regards, Barry
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