In the November 2017 newsletter, I talked about cold testing teeth to determine pulpal vitality. The cold test is by far the most commonly employed of the pulp tests and for the most part the easiest to use.
The hot test, while used less frequently, is another important pulp vitality test. As with cold testing, there are a number of methods to do a hot test. We can place a rubber dam on the tooth and submerge the tooth in hot water. The water has to be hot. I like it hot enough that I can’t leave my finger in it for longer than 1-2 seconds. A second method is to use some heated compound or gutta percha (GP). Place the bubbling hot GP, heated with a lighter, on the wet buccal surface of the tooth. A third way is to wrap a cotton roll dipped in the hot water over the buccal, occlusal, and lingual aspect of the tooth.
The key with all hot test is to keep the heat on the tooth until the patients reports a response. This may take up to a minute. I ask the patient to tell me when they first feel the heat. At that point, I remove the heat and then I ask the patient to tell me when the sensation is gone. It also helps to have the patient rate the pain response on a scale of 1-10.
My preference is the hot water/cotton roll method. It is easy to use and contain the heat to just one tooth. Again, make sure the hot water is very hot. I use a 180-degree hot water dispenser and will often microwave the water for another 10-20 seconds. I wrap the cotton roll over the tooth and hold it in place until I get a response. Watch the patient’s eyes. That will often indicate a response and the degree of the response before the patient tells you verbally.
I use the heat test when the patients reports in their history they are experiencing pain to hot foods or drinks. Pain to hot that lingers is indicative of a damaged pulp requiring endodontic treatment. Of note, a negative response to a hot test is not indicative of pulpal health or pulpal death. Some calcified teeth just do not respond to heat. Always keep some ice handy when doing the hot test. A tooth which has no response to cold may, depending on the stage of pulpal degeneration, respond with intense pain to heat. Applying cold to the tooth will usually abort the pain created by the hot test. As with all pulp tests, multiple tests need to agree to reach a confident pulpal diagnosis.