Root Canal 101

Young Bui, D.D.S.
Root Canal 101

Young Bui

ROPER rubber dam isolation is the important first step in performing a root canal treatment. If there is not enough tooth structure above the gum line to place the clamp on, you must first build up the tooth. Mix a small amount of Ketac cement and inject it onto the tooth structure as you would with a core build-up. Once the Ketac is set, you can clamp the tooth without causing injury to the gingiva. Next create a straight-line access. If you are worried about perforation, the PulpOut® Bur is a good instrument to use. It has a stop to prevent you from going too deep and a non-cutting tip barrel diamond to create the perfect straight-line access. This will allow sufficient light into the chamber for you to locate the canals easily.
Once the canal is located, use a #6 or #8 reamer to negotiate down to the apex. Next, get the working length using the apex locator. The reamer should be a nice fitting one in order for you to get a proper reading. Instrument the canal using the Safesiders® reamer up to #25. Be sure to flood the chamber with sodium hypochlorite during the instrumentation process. The solution will aid in removing debris from the canal to prevent blockage and also act as a lubricant. After you have reached the apex with a #25 reamer, use the #2 Gates Glidden (GG) to go down the canal. Do not use force once the forward progress stops. By using force, you will pack debris into the canal and block yourself up. Irrigate and renegotiate the canal with a #10 reamer to the apex to break up the debris build-up. Use a #2 Peeso reamer in a light pecking motion down the canal. It should go down easily by following the path of the GG. Again, do not use force once there is resistance. You will either perforate or ledge out if you push too hard. Irrigate and renegotiate with a #15 reamer to the apex. Once the canal is clear of debris, go in with the Safesiders #30-40 reamers to the apex. Next go in with the orange NiTi 30/.04 to the apex. Irrigate with EDTA and then go in with the brown NiTi 25/.08 to the apex. If you have a hard time getting this file down, you might want to go back in with the GG again to see if it gets down any farther. You do not have to get it down all the way to the apex. Irrigate with EDTA again after the last instrument and then soak it with 2 percent chlorhexidine for at least two minutes. Dry up the canal and apply EZ-Fill® cement along the canal wall with the bi-directional spiral. Fill the canal using the appropriate size gutta percha point. I normally use the Diadent 30/.06 taper point if I can get the brown NiTi down to the apex and if the working length is 21 mm or less. If the working length is longer, then I would use the medium point from Dentsply. Remove the excess cement using cotton pellets soaked in alcohol.
If you happened to ledge out with a Peeso reamer, take a #10 reamer and make a bend at the tip. Insert the reamer down to the point of the ledge and twist the reamer until it falls back into the canal. Now take a #10 Hedstrom and do the same thing with it. Once you get the Hedstrom beyond the ledge, start to ream up and down along the ledge wall to create a smooth curve for the reamer to go in smoothly. Keep on doing this process as you increase the size to a #30 Hedstrom. By this time, the ledge should be smoothed out and the #30 reamer should get past the ledge easily without pre-bending.

September - October 2006

Do not use force once the forward progress stops.

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For a very effective antibacterial irrigation liquid, use 2 percent chlorhexidine, NOT Peridex, which is only 0.12 percent.