Your dentist told you that he was about to conduct a cold test on your tooth. That made you raise an eyebrow because you have no idea what that even means. Then he proceeds to spray a cotton pellet with something in a can for a few seconds and place the pellet on your tooth.
OUCH!
What on earth was that and what was its purpose? Was your dentist trying to torture you for no apparent reason because it felt extremely cold.
Let us explain what the purpose of this procedure is and the meaning of the test results. It may be a little ambiguous to you but you're not alone because a lot of newly graduated dentists don't understand it either.
Most people interpret the results of a cold test on a tooth incorrectly.
Purpose
A cold test on teeth provides information on the vitality status of the tooth pulp but its results are relative and not absolute. Based on the results, your dentist can make a decision whether to treat the nerve with a root canal or not.
Tooth nerve's vitality status
What the cold test tells you is the health status of the tested tooth nerve.
Is it a dead tooth or is it still alive?
If it is alive, is the nerve healthy?
A tooth that has died will not respond to the cold but one that is vital will respond to it. Essentially if the tooth is alive, it will feel the cold while the dead one will not feel anything.
Teeth that feel the cold does not mean it is healthy. It is certainly still alive but the health status depends on how it responds to the cold. A delayed or lingering response is an indication of it being unhealthy despite being able to sense cold.
Relative results
The cold test results do not give absolute results but rather relative results. In other words, we cannot use the same absolute scale to compare patient to patient. What you need to do is to create an individualized scale to evaluate each patient.
The reason is because everyone's nerve responds differently and has a different baseline response. As an example, the cold lingering for 5 seconds could be normal for subject A while an 8 second linger could be normal for subject B. It doesn't mean that subject B is less healthy than subject A.
You need to establish what is normal for each person and compare the tested results to that baseline. Basically the point that we're trying to get across is that the results are relative. Without perspective and taken out of context, the results of a cold test are meaningless.
How to cold test a tooth
The cold test itself is very simple to conduct. It should only take about a minute and requires very little supplies.
Supplies for cold test:
Endo Ice
Cotton pellet
College plier
Gauze
Dry. With a piece of gauze dry the teeth.
Spray. Hold cotton pellet with college pliers and spray it with endo ice for 5 seconds.
Test control tooth. Place cotton pellet on a tooth adjacent to tooth in question.
Remove cotton as soon as patient feels the cold.
Note time it takes to feel the cold.
Note how long the cold lingers.
Spray. Hold cotton pellet with college pliers and spray it with endo ice for 5 seconds.
Test the tooth in question. Place cotton pellet on the suspected tooth.
Remove cotton as soon as patient feels the cold.
Note time it takes to feel the cold.
Note how long the cold lingers.
That's all of the steps for the test. Now all you have to do is to compare the results and interpret what it means. Essentially you should be able to come up with a diagnosis for the status of the tooth's pulp.
Why test a control tooth?
Cold testing a control tooth first provides a baseline response for you to compare results to. After all this is a relative test and you need to know what is considered normal for your patient. If you don't use a control, you won't know what is normal or abnormal.
Since this is a relative test, the results are meaningless or not as meaningful without any context. Knowing how a normal healthy tooth responds will provide a lot of clarity to the results.
How to choose a control tooth
Ideally for the control tooth, you want to choose the same type of tooth in the same quadrant.
If you suspect an upper right molar to be unhealthy, you should use a different upper right molar as the control. Do not use an upper left, bottom left or bottom right molar.
If you suspect an upper left premolar to be unhealthy, you should use a different upper left premolar as the control. Do not use an upper right, lower right, and lower left premolar.
The reason you want to use the same type of tooth in the same quadrant is because they're on the same nerve. Testing a different type of tooth will be testing a different tooth nerve so the baseline for normal may not be as accurate.
Upper incisors are grouped into the anterior superior alveolar nerve.
Upper premolars are grouped into the middle superior alveolar nerve.
Upper molars are grouped into the posterior superior alveolar nerve.
Essentially you want to be testing on the same nerve.
Exception: If the patient is missing the same type of tooth in the same quadrant. If that is the case you would have to use a different type of tooth but choose one in the same quadrant. That does decrease the results certainty but you have to work with what you have.
How to interpret the results
There are three pieces of information taken from a cold test in order to formulate a diagnosis for the tooth's nerve.
Does it feel the cold?
Time it takes to feel the cold.
How long does the cold linger.
Attributes | Healthy Pulp | Unhealthy Pulp |
|---|---|---|
Can it feel the cold? | Yes | No |
Cold onset | Instantaneous | Delayed response |
Cold lingering time | Couple seconds | Long lingering time |
Can it feel the cold?
A dead tooth cannot feel the cold nor is it bothered by it. There will be no response from it if it has truly died. A tooth that is alive will feel the cold and it will be bothered by it.
Vital tooth will feel the cold.
Non-vital teeth will not feel the cold.
Basically, a cold test on tooth with no feeling means it is dead.
Time it takes to feel the cold
The time it takes for the tooth to start feeling the cold tells you how healthy the nerve is. If the response is severely delayed it may potentially mean the tooth is dying.
Instantaneous response means the nerve is lively and healthy.
A severely delayed response means the tooth is probably dying and on its way out.
How long the cold lingers
The cold response should linger for a few seconds at most while the tooth recovers from the stimulus. It should be quick for healthy teeth but for unhealthy teeth it can linger on and on and on. Unhealthy nerves don't recover from stimulus as quickly.
A few second linger means the nerve is healthy.
An extended period of lingering means the nerve is unhealthy.
Examples of cold test interpretations
Here are a couple of cases for demonstrative purposes on how to interpret the results and the treatment needed. If professional intervention is required it would most likely be a root canal procedure, where the unhealthy nerve gets removed.
Example #1
Attributes | Experimental Tooth | Control Tooth |
|---|---|---|
Can it feel the cold? | Yes | Yes |
Cold onset | 3 seconds | 4 seconds |
Cold lingering time | 20 seconds | 5 seconds |
The suspected tooth feels the cold test but it lingers for a lot longer than the control. The tooth nerve is certainly unhealthy.
Diagnosis = pulpitis
Treatment = root canal
Example #2
Attributes | Experimental Tooth | Control Tooth |
|---|---|---|
Can it feel the cold? | No | Yes |
Cold onset | None | 3 seconds |
Cold lingering time | None | 3 seconds |
The suspected tooth cannot feel the cold while the control can, this means that the tooth is most likely dead.
Diagnosis = necrotic pulp
Treatment = root canal
Example #3
Attributes | Experimental Tooth | Control Tooth |
|---|---|---|
Can it feel the cold? | No | No |
Cold onset | None | None |
Cold lingering time | None | None |
If neither the experimental tooth nor the control tooth can feel the cold, the results are actually inconclusive. Just because they don't feel it, it doesn't necessarily mean the tooth is non-vital nor does it need a root canal.
After all this is a relative test and perhaps in this case, cold testing may not be the best form of testing. The chances of multiple teeth being dead are highly unlikely!
Diagnosis = inconclusive
Treatment = try a different vitality test
Takeaway
Cold tests are used on your tooth to check the vitality and health status of the nerve. The results are relative in nature and not meant to be interpreted as absolute values. It is of utmost importance to compare your findings to an appropriate control tooth.
That is the only way to come up with an accurate diagnosis and treatment for the tooth in question. If you're in need of a cold test, our dentists in Long Island City can test your pulp's vitality during the
appointment.
