Heat testing for dental pulps

 Today I had a situation where I had to heat test some teeth to diagnose where the patient's pain was coming from. The situation was lingering pain from a lower molar elicited by hot and cold stimuli. The cold test was being inconsistent and wasn't reproducing the lingering pain that the patient was describing. I was given a Q tip to carry the cold spray but I find that looser materials such as cotton rolls or cotton pellets are better at carrying the liquid and will retain the cold for longer. It may have been that my method for cold testing wasn't efficient enough at carrying the cold into the tooth. The carrier for cold will warm up quickly once in the mouth and it may not be cold enough to elicit a response from the pulpal nerves.

I wasn't getting anywhere so I decided to heat test the pulps. It has probably been about 5 years since I've had to do this but in the odd time that it is used, it is very useful in reproducing their pain. A few methods for heat testing exist and I've heard of people using heated GP sticks as well as cotton pellets to carry hot water similar to cold tests. However, a few endodontists have said that they think the most reliable method is to use hot water under rubber dam so this is the method that I use. A few points:

-Normal pulps should have little to no response to the heat similar to when you have a cup of coffee or tea. The C fibres are the ones that depolarise in response to heat and these aren't normally activated without significant inflammation in the pulp. 

-The first tooth I tested, the second molar had no response but he did have a response when the dam leaked and burnt his gingiva slightly. Ensure the rubber dam has a good seal. I placed it the conventional way with a winged clamp but didn't manipulate the clamp to ensure a good seal. I found it much easier for subsequent tests to stretch the dam over the tooth then place the clamp. A very stretch dam such as Roeko Flexidam is really useful in getting the dam stretched all the way to the posterior. The purple dam is also slightly thicker than other dams so it is more difficult for the heat of the water to travel through the dam and harm the tissues. 

-Test the most posterior tooth first to ensure there are no false positives from water leaking backwards and hitting a more posterior tooth.

-As C fibres are the ones that react to the heat, expect a profound pain response from the patient. This will be a deep ache and elicit a strong emotional response. The patient in this case felts severe pain from the first molar. Ensure your assistant has the slow speed suction ready to clear the water once the patient has a response. If the response is strong and you are sure of the diagnosis then get the dam off and give local anaesthetic to get the patient out of pain. Have the syringe ready to go before you start the test. This is important as from the pain history, the pain will be severe and lingering and simply suctioning the water out won't stop the pain.