An x-ray is one of the most common tests used to examine tooth root damage. However, this is not the only test your dentist may subject you to if he or she suspects tooth nerve damage. Other possible tests include:
This is one of the simplest tests the dentist may perform. It just requires the use of a solid dental instrument, which the dentist uses to tap the tooth suspected to be harboring root damage. The test works because the crown and dentin part of a tooth may look normal while its interior is decayed.
The vibrations from the tap are transferred to the roots nerve, and you are likely to feel pain if the tooth that is being tested has a degenerated root. Dentists usually start the test by very light taps that are then increased in intensity to gauge how painful the tooth is.
The electric pulp test is used to determine the vitality of the nerve inside your tooth. It gives an indication of whether the nerve is dead or alive. In this case, the dentist introduces an electrical current to your tooth by holding a probe against the tooth. If your tooth is alive, then you will get a tingling sensation in it. You shouldn't be concerned about electrical shock because the current used is very weak.
A thermal test is another form of vitality test that determines the status of a tooth's nerve. This involves applying hot and cold stimuli to your tooth and noting the effect.
Dentists have different techniques for applying cold stimulus to a tooth. For example, your dentist may dampen a piece of cotton wool with ethyl chloride (a refrigerant) and place it on the tooth. If you feel the cold, or if it relieves toothache, then there is a problem with the root or nerves.
As for a hot stimulus, the common mode of application is via the use of a heated Grater Taper (GP). The dentist may coat the tooth with a small film of petroleum jelly so that the GP doesn't cause damage. If you feel pain that doesn't go away immediately after the GP is withdrawn, then you may be having a damaged nerve.
Note that one test may not exclusively reveal the presence of root damage; a combination of several tests may be necessary for a proper diagnosis. This is because there may be other dental problems that may elicit similar responses if a single test is used. For example, you may feel pain (even without nerve damage) if you have excessively sensitive teeth.