Most patients having a root canal do not find it to be a painful procedure. Most Dentists have a great deal of experience in getting teeth anesthetized.
If I am starting a root canal and my initial attempt(s) at achieving anesthesia do not achieve the desired results, there are a number of additional options available, including intraligamental, intrapulpal and intraosseous anesthesia.
Assuming that my initial block or anesthetic was not entirely effective, I find that many times intraligamental injections make a root canal patient comfortable. Intraligamental injections results usually are best achieved when a dentist uses a special intraligamental syringe that delivers a few drops of anesthesia under pressure at the four corners of a tooth. When properly administered, this type of anesthesia will make a patient comfortable during their root canal. The only drawback is that occasionally teeth given an intraligamental injection become slightly tender for a day or two when a patient applies chewing pressure.