ApPENDIX
F:
DEALING WITH THE CURVED CANAL
DEALING WITH PROBLEMS OF THE CURVED CANAL:
BLOCKAGE, LEDGES,
TRANSPORTATION, ZIPS, ELBOWS AND STRIPS If all canals were straight, endodontics would be much simpler and require minimal instruction. Howev足 er, the truth of the matter is that all canals are curved to some extent. The greater the curvature, the more difficult the problem and the more complicated the cleaning and shaping of the curved canal. Complexity and degree of curvature is what generally makes molar endodontics night and day different from "simple" anterior RCT. Start all canals with a gentle bend in the file. Blockage: You can block yourself out quickly and easily even in a straight canal in two ways: I.Failure to religiously use lubrication (such as Glyde, RC Prep, etc .) in the canal during initial nego足 tiation with your scouting file. This is especially true with a vital pulp. Believe it or not, if you poke into the pulp without lubrication, the collagen will form a solid mass in the canal which can become harder than the dentin. Failure to lubricate at the outset and following can prevent you from ever reaching patency. 2. Failure to religiously irrigate (NaOCI) and 3. Failure to recapitulate to patency with your #10 or #15 patency file following each active instru足 ment will generally guarantee a blockage as the dentin chips and filings can quickly create a plug which is harder than the dentin of the canal. If you have ever drilled a hole in concrete, you know that you must stop periodically and blow or wash out the filings or else your drill ceases to advance. The principle is the same. Sometimes, blockages can be cleared or bypassed successfully, but blockages seriously and unnecessarily escalate the difficulty and time requirements of the job. It is much easier and more desirable to prevent the blockage by adherence to these basic principles. Curved Canals: With curved canals, one becomes concerned with not only blockage, but also ledging and transportation of the canal which leads to apical zipping and elbow creation as well as possible api足 cal perforation or even strip perforation. Curvature of canals vary greatly and can be qu ite severe (F ig. 1). Note the 75 degree curve on the mesial canal. This would be a challenge to treat successfully for any endodontist. The 25 degree curve seen on the distal canal is considerably easier to treat but demonstrates the same principles but to a lesser severity. Your lab teeth should have been selected to have no greater than 20 degree curves. Of course, you will encounter non-selected canals in the Clinic. You must understand how to deal with these curves which are found in all teeth .
Figure 1
Endodontics Manual II
- 82-
Revised 09/'09