The very word “Root Canal” is enough to strike terror into the heart of an otherwise compliant dental patient. So what are root canals and why are they often feared?
Figure 1 shows the anatomy of a tooth with enamel (the white external part of a tooth) and dentin (the yellow part of the tooth under the enamel) and blood vessels and nerves (pulp) inside the tooth. For a variety of reasons the pulp can become inflamed or necrotic (dead) and have to be removed. The process of removal of the pulp and filling the pulp chamber is called a “root canal”.
The process of doing a root canal is the process of removing the pulp (either alive or necrotic), and filling up the resulting space. Figure 2 shows the pulp being removed with an endodontic hand file. Generally pulp is removed first with hand files and then with rotary Nickel Titanium files.
The process of removing the pulp is frequently the most painful part of the root canal procedure. To be pain free it requires good anesthesia. Neither Nitrous Oxide (laughing gas) or IV Sedation (a needle in the arm) alone will give adequate anesthesia. Good block or Infiltration anesthesia or Intraosseous anesthesia is required for a pain free experience. Intraosseous anesthesia is the injection of local anesthesia directly into the bone surrounding the tooth, and nearly always gives a pain free result. A good question to ask your root canal doctor is whether or not he uses intraosseous anesthesia.
After the pulp is removed the empty space of the root canal system must be filled. The accepted filling material is called “Gutta Percha”. Usually the Gutta Percha filler is coated with a substance call “sealer” to fill in the gap between the GP Point and the canal walls, as illustrated in Figure 3.
After completion of the root canal process the tooth is “hollow”, and it is frequently recommended that the tooth have a crown (cap) to strengthen it. Sometimes it is also recommended that the canals be reinforced with metal “posts” to give the restored tooth more strength.
If all this sounds simple it really isnʼt. No discussion of root canals would be complete without mentioning the things that can go wrong. Figure 4 shows what is called an accessory (side) canal. Failure to fill these canals can result in root canal failure. Figure 5 shows a highly curved canal that could not be instrumented. Figure 6 shows a crack in the root of the tooth which frequently leads to root canal failure.
So, should root canals be done by a specialist (endodontist)? Although the probability of success in root canal treatment is the same (90%), endodontists have tools that most general dentists donʼt have. Such things as CT Scan Machines, Surgical Microscopes, and Gentle Wave cleaning systems. Sometimes these things can make a difference.