STS is the New Automated Endo Standard

Lynchburg, Virginia ...

August 26, 1994
Latest Update Saturday, January 17, 1998

Well, I've bitten the bullet! Watch for an announcement soon.

The STS sysem which we have been using for the last three or four years will soom be replaced with the new Fine Cut Endo Handpiece

We are now teaching the Successor To Sonics (STS) system as the main method in the Automated Endo course.

Sonics and ultrasonics are still there but in a minor role.

In mid-July I had occasion to do a root canal on my father who is a very young 81 years of age.

It was the lower right first premolar.

It was a fairly straight-forward 21mm canal that had to be probed for almost it's entire length, meaning that when I started circumferentially filing the canal was size 15 for its entire length.

After gaining access and measuring, I decided to use the STS as an orifice opener.

I began spiraling down using a size 25 Fine Cut File and in less than a minute I was at the 3mm point and just for fun, decided to circumferentially file for a few seconds.

After another 30 seconds, I was able to drop a size 40 to the 3mm point.

At that point concept became reality for me.

This thing really works!

Since then several techniques have emerged for use with the STS system.

  1. It is still necessary occaionally to move the file in and out of the canal to keep water flowing to remove debris.

    I have found that moving the file almost completely out of the canal and reinserting it every five or six seconds is more than adequate to prevent debris buildup.

  2. A couple of drops of water every few seconds is all that is needed for washed field.

  3. Doing flat, ovoid, crescent shaped, and ribbon shaped canals are especially easy with the STS by using a crossover method.

    Since the STS cuts so fast you don't want to leave it in any one place for very long as it will cut a pretty good groove.

    On a flat surface keep changing the angle of approach and pretty soon you can feel the roughness disappear.

    The motion is a sweeping motion.

  4. Push-Pull probing with the STS is also easy.

    It is interesting to note that since the file only moves up and down about 0.8 mm there is very little danger of buckling while probing.

    Even if the file hits dead into something the downward pressure will simply bow the file, not buckle it.

    There are a few caveats, however.

    Since the Fine Cut File has a positive rake, it goes in easier than it comes out.

    If you are probing a curved canal where the canal is already larger than the file you are using, the file will tend to pull itself in as the linear oscillation pushes the file inward and your tendency is to follow it.

    It would be necessary to hold back on the STS to get it to cut on each out stroke.

  5. Removing old cement filling material is also easy.

    Select a file that is smaller than the canal and with lots of water flowing, push the file into the canal.

    The effect is that of a pointed tool on a jack-hammer.

    The file gets driven in on each down stroke.

    Since the cement breaks away on the up stroke, there is no tendency to pull itself in.

  6. Circumferential filing around curved canals REQUIRES that you pre-curve.

    If an aneurism can be created by hand filing, it will be created in almost no time with 500 strokes per second in the STS system.

  7. If you are very careful and have a good apical length measurement and don't blame me for your mistakes, you can also dress the apex to size by probing the last 3mm with a size 20.

    You lose the accuracy of the hemostat stop but there is very little danger of breakage because the file bows, not buckles.

  8. Recent research into file wear shows that all files get dull after several hundred strokes and they are become less and less effective.

    I suppose the same is true of Fine Cut Files.

    It is not a good idea to re-use these or any files.

  9. If you turn the STS on before entering the canal with the file, the file tends to flop around and makes it difficult to get the point in the orifice.

    Orifice opening helps.

    If you simple hold your finger against the side of the file while entering the canal it helps stabilize it and make introduction easier.

  10. The basis of the free-floating action of the Fine Cut System is that there is a little up and down freedom of movement in the file well of the Fine Cut Adapter.

    This can cause trouble when probing.

    Since the STS only moves up and down a small amount, the result is that the file doesn't move up and down enough.

    There is a little trick you can use to eliminate this problem when probing.

    Simply put the file in the adapter head first, then slide the Safety Shroud against it holding it in place.

    Now the file movement is much more vigorous.

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