Root canal dentistry drill. This long, thin drill is designed to drill down to the root canal of a tooth during root canal dentistry. This surgery can take several hours. The first stage is the drilling, cleaning and disinfecting of the tooth's root canal. The cavity is then filled. One technique is to use an injection gun to fill the hole with the hot gutta percha gum (over 200 degrees Celsius). The temperature and the use of an injection gun ensures the gum fills all of the hole. This specialist technique helps avoid later infection, which can result in an infected tooth that needs to be extracted, and can also cause damage to the jaw bone.