NICKEL-TITANIUM FILES
INTRODUCTION:
The design of the endodontic files has come a long way in the last one hundred years since the first creative soul unwound a watch spring, passed it through a flame to sterilize it and extirpated the first pulp! Although early manufactured metal files were an improvement, they were neither standardized nor flexible. Over the years, we enjoyed the ISO standardization of files, and the flexibility and sharpness of stainless steel instruments, which became the standard for endodontic treatment. In the last five years, we have entered a new era in endodontic file design. The material leading this revolution is nickel-titanium and the changes in instrument design are numerous.
DESCRIPTION:
Nickel-titanium is a space age material of incredible flexibility and strength. Cutting flutes are cut into the instrument, unlike traditional k-files and reamers, which are twisted to obtain a cutting edge. Some of the manufacturers with different file designs are:
- Tulsa: Profile Series 29 - Produced in both hand and rotary style, instruments feature a constant increase of 29% from one size instrument to the next. Instruments are available in tapers of .02, .04, and .06.
- Tulsa: GT Files - These are variably tapered files in four sizes, designed to shape the apical portion of the canal. All instruments are a size 20 at the tip, varying in taper.
- Lightspeed: Features a series of instruments in ISO sizes and half sizes for rotary instrumentation. The instrument consists of a cutting head only (similar to gates-glidden in appearance) on a flexible shaft.
- Quantec: The most recent configuration from McSpadden and the NiTi company.
ADVANTAGES:
The main advantage of nickel-titanium is related to its exceptional elasticity and flexibility, with superior resistance to torsional fracture. As a result, the instruments can produce less apical transportation of curved canals. These properties also allow the use of the instruments in rotary handpieces, and the construction of varied instrument designs.
OUR EXPERIENCE:
We have been using some form of nickel-titanium instruments for the last four years. The early instruments we have tried (many of which are no longer on the market) were not acceptable. More recently, we have been using the Profile instruments, and we are pleased with the results so far. Although we thought they would be significantly faster, that has not been the case. Their ability to negotiate curved canals without apical zipping and stripping is excellent. The use of rotary instrumentation decreases operator fatigue, which is a factor when you're doing it all day!! But beware, there are certain drawbacks. Originally, it was thought that the instruments were extremely resistant to breakage and they could be repeatedly sterilized without loss of sharpness. Regrettably, that is not true. They are better than stainless steel; however, they are susceptible to separation. In addition, the cutting flutes dull with sterilization and the instrument breakage potential also increases with sterilization. Instead of lasting twelve to fifteen uses before retiring a set (the early promises), it is only one to five uses (depending on the system). Last but not least, the instruments are very expensive (about five times more than stainless steel). Overall, we are glad to be able to add the nickel-titanium instruments to our armamentarium, and think they are advantageous.
ENDO FACTS is intended to aid the practitioner in the management of endodontic conditions. Practitioners must always use their own best professional judgement. We neither expressly nor implicitly warrant any positive results associated with this material.
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