Pulp testing for calcified pulps

Root canal systems calcify and dentine undergo scleroses in response to function, ageing and insults to the pulp such as repeated thermal or chemical insults (erosion, caries). As the dentinal tubules close, the ability for fluid movement to stimulate the pulp is reduced. Deposition of secondary and tertiary dentine increases the bulk of avascular tooth structure between the environment and the pulp tissue. This is beneficial for protecting the teeth against further insult but does raise difficulties during diagnosis of dental pain.

When we are diagnosing pain we want to identify the odd tooth out e.g if there is a pulpitis we want to identify which tooth has an exaggerated response to stimulus compared to the surrounding teeth or if there is a pulp necrosis we want to see which tooth has no response compared to the surrounding teeth. Dentine sclerosis and pulp recession makes all responses less obvious and can complicate diagnosis.

Technically the majority of tests we utilise for determining vitality test sensibiliy or the pulp's ability to initiate nociception. This ability may be absent in vital pulps. Pulp vitality testing on the other hand would be testing the presence of a blood flow through the pulp system of which there are no widely used methods.

Electric pulp tests runs an electric current through the tooth to more directly stimulate nociceptors. Electrical conduction through the tooth will be more efficient than thermal conduction therefore this test is very useful for calcified pulp systems. Do be sure to isolate the tooth in question from the adjacent teeth by drying them from saliva and using a plastic matrix strip between the teeth especially if there are adjacent amalgams present. Failure to do so may result in false positives. Use a conductor such as toothpaste to allow the electrical current from the tester tip to contact the tooth surface well and be sure to follow the instructions as all systems will requite separate skin contact with the patient to complete the circuit.

Traditional cold spray on a cotton pellet may not be as effective in calcified cases as the pellet quickly equalises its temperature before placement on the tooth. Oversaturating the pellet with cold spray may lead to leakage of the fluid onto the adjacent teeth and gingiva. Consider using CO2 ice which is directly connected to the source of cold. This can reach far lower temperatures and will stay at a constant temperature throughout. Using a whole cotton roll and spraying the end of it will allow more cold spray to be soaked in and will stay at a cold temperature for longer as well as having a higher surface area to contact the tooth with. However it can't reach as low of a temperature as CO2 ice due to the temperature of the spray as it exits the nozzle.

As well as being less likely to elicit a response in the first place, calcified pulps may give a vague sensation that the patient may be unsure if they should respond to. You must leave the cold stimulus on the tooth for long enough to ellicit a proper response. If the patient is unsure, try again but leave the cottol roll on for a few seconds longer.



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