Determining Pulpal Status – The Cold Test

An accurate determination of the status of the pulp is a critical element in achieving the correct diagnosis and treatment plan.  How the pulp responds to a thermal challenge, both for a specific tooth and comparatively in relation to adjacent and opposing teeth, gives the dentist important information about the health of the pulp tissue.

Our textbooks give a list of diagnostic categories for the pulp from normal to necrotic.  Each of these categories; normal, reversible pulpitis, irreversible pulpitis, pulpal necrosis, comes with a list of how the pulp responds to thermal challenge.  The challenge for the dentist is that the pulpal health proceeds through a continuum from normal to necrotic.  This continuum can change slowly or quickly, from when the patient first becomes aware of their tooth till the pulp becomes necrotic.  To further complicate the issue is the timing of when we actually do our testing.  We may be in between the categories and the thermal responses may not line up with a specific diagnosis.  Nonetheless, we should have a well thought out, repeatable protocol for pulpal testing.

The first go to pulp test for me is the cold test.  There are a number ways to test for cold.  We can blow air or spray water on the tooth and determine the patient response.  We can place a stick of ice on the tooth.  Alternatively, we can use a spray refrigerant such as ethyl chloride.  Each of these techniques may elicit a pulpal response.  The key is that the cold challenge needs to be isolated specifically to a single tooth at a time.  Air or water spray can be difficult to limit to one tooth.  For this reason, the use of air or water spray is not the cold test of choice for me.

Refrigerant sprays such as ethyl chloride can be useful and can be colder than ice which is helpful in calcified teeth or teeth with crowns.   The refrigerants rely on condensing water from the humidity in the air and turning it into ice.  They are very convenient, easy to use, and can be easily localized to an individual tooth without overlap.   My experience is that as the humidity in the office changes the degree of ice developed from the refrigerant can vary from one season to the next and sometimes from one day to the next.  Another concern is that the degree of coldness changes over time as the refrigerant vaporizes and the amount of ice on the cotton applicator decreases.  This can result in variability of response through a quadrant.

My choice for the cold test is a simple stick of ice.  It is easy and cheap to have around, easy to isolate to a specific tooth and is extremely consistent from one tooth to another in the same or opposing arches, as well as from one patient to the next, regardless of the day or season.

We make the ice in office.  We take empty, sterilized, anesthetic cartridges with the rubber plunger removed, fill them with water and freeze them in the staff room fridge/freezer.  When a cold test is required, simply hold the cartridge in your hand and with cotton pliers remove the stick of ice.  Wrap it in a 2×2 with 5-6 mm of ice exposed.  Place the ice stick on the neck of the tooth in the gingival third and soak up the ice melt with a cotton roll.

Ask the patient tell you when they first feel the cold (or some like sensation), remove the ice, and ask the patient when the feeling has gone.  Completely.   Note the degree of the tooth response, usually 0, +, ++, or +++, and how long till the tooth returns to normal sensation.  A key point is to look at their eyes as the ice hits the tooth.  You often see a change in the pupils or squinting of the eyelids when a painful response has occurred regardless of what they say to you.  A lingering response to cold challenge that lasts longer than 30 seconds is often an indication of a degenerating, pulpitic pulp requiring endodontic intervention.



Dr. Howard Bittner, DMD, CAGS

Dr. Howard Bittner, DMD, CAGS

Dr. Bittner was born and raised in the Surrey / Langley area. Following his pre-dental training at Simon Fraser University, he received his Doctor of Dental Medicine from the University of British Columbia in 1982 and his Certificate in Advanced Graduate Studies in Endodontics from Boston University’s Goldman School of Dental Medicine in 1995.
Dr. Bittner was in private practice in general dentistry for 11 years in Langley before his Endodontic specialty training. He has been practicing Endodontics since 1995.
In his free time, Dr. Bittner loves to participate in a variety of sports including golf. He also enjoys being a grandfather to 4, which if you ask him is just the best!

On November 9, 2017, posted in: News for Doctors by

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