Meeting the Challenge of Curved Canals

Young Bui, D.D.S.
Meeting the Challenge of Curved Canals

Young Bui

NE of the greatest challenges in performing root canal therapy is instrumenting an S-curve or a reverse curve. You need to take it slow and be patient with your instrumentation. The most important thing is to maintain patency. Patency is the key to a successful navigation of the curves. I have had many experiences in which I skipped one little step and ended up blocking myself out. Once you have blocked the canal in a case like this, you can forget about trying to unblock it. Just fill it to that point and call it a day. The worst thing you can do is to use a crown-down technique to open up the canal. Doing so can pack debris down the canal, resulting in a roadblock. The following is a step-by-step process that I used in cleaning the two molars seen in the x-rays.
    The first step is to get the #6 or #8 reamer down to the apex, using an apex locator. If you can’t get the reamer down all the way, you might want to consider sending the case out to a specialist.
    Once the apex has been reached, fill the chamber with sodium hypochlorite. The sodium hypochlorite will lubricate the canals during instrumentation and aid in the removal of debris. I began by cleaning the canal 1 mm beyond the apex to keep it patent.
    After using each reamer in the sequence of increasing sizes, I would go back in with the #8 reamer to make sure that I did not block myself out.
    Once I reached the apex with the #25 reamer, I took a #2 Gates Glidden down the canals with a light pecking motion. Do not force it. Just let it ease into the canal. If you force it, you will block yourself out or ledge the canal.
    Irrigate the canals and go back in with the #8 reamer to keep it patent.
    Next I took the #2 Peeso reamer down the canals with the same light pecking motion. Always remember to irrigate and re-instrument the canals after each step to prevent blockage.
    After the Peeso, I instrumented the canals up to a #30 reamer. I then took the 30/.04 NiTi (orange) down to the apex. This is a great instrument for removing debris along the walls of the canals at the apical end.
    I finished the instrumentation with the 25/.08 NiTi (brown).
    The canals were then dried with paper points and coated with EZ-Fill® cement. I used a fine gutta percha cone to coat the canals with the cement. You will break the bi-directional spiral in curved canals like these. I used a single cone to fill each of the canals with cement. The x-rays that follow show the beautiful results that can be obtained with the SafeSiders® technique in dealing with curved roots.

April - June 2009


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FIGURE 5	FIGURE 6

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Remember to make sure to get a reliable, accurate, and repeatable reference point when taking your measurement control. Sometimes it may be necessary to flatten a cusp tip rather then use the cusp slope when measuring. You can use an indelible marker to make a small mark on a crown surface to give yourself further accuracy and repeatability during the visit. Also remember to re-measure as you instrument because canal straightening ultimately can shorten your measurement control by .5 mm to as much as 1 mm.

Doug Kase