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Discoloured Teeth: It’s Not Black & White

dentistry & oral surgery featured free

Were you told to “watch” these discoloured teeth when you entered small animal practice?

I know I was!

But WHAT are we “watching” for exactly? The colour to change? Signs of oral pain? Evidence of tooth root ‘abscess’?

I am here to tell you just “watching” will not provide you with any meaningful information.

So what is meaningful when it comes to discoloured teeth?


Let’s take a quick step back to WHAT makes a tooth discoloured.

Teeth can have external staining or discolouration or internal discolouration. We are talking about the INTERNAL discolouration here.  That grey-to-beige-to-pink-to-purple gradient of discolouration is a BRUISE. What you are seeing is hemoglobin particles that have been able to make it into the dentinal walls following hemolysis within the pulp tissue secondary to trauma.

When you think of the discolouration of a tooth as a bruise, it’s easy to understand that this indicated a non-vital of DEAD tooth.

This conclusion is supported by the literature. The first paper published on discoloured teeth in 2001 found that 92.2% of discoloured teeth were found to be non-vital based on gross examination of the pulp tissue.1  The second paper published on this topic, found 87.6% of discoloured (instrictically stained) teeth were non-vital based on pulp necrosis on histopathology.2 There was also another 3.1% of these teeth that had evidence of pulpitis on histopathology. While it cannot be assumed, it can by hypothesized that those teeth with pulpitis would go on to develop pulp necrosis – given a 90.7% rate of non-vitality.


What about radiographs to be sure?

For me the most interesting result of these two studies is that ONLY 57% of these teeth that were confirmed to be non-vital HAD radiographic signs (wider pulp chamber and/or periapical pathology. That means that using radiographs to decide on treatment is ONLY 50:50.

While radiographs are important, and should be taken on every patient as part of every Comprehensive Oral Health Assessment & Treatment(s) – COHAT; they are not as reliable as the literature when it comes to discoloured teeth.


Putting this into a clinical setting:

Every discoloured tooth should be documented as such, and the owner should be informed of the 90-93% probability of non-vitality. Therefore, I personally recommend making the recommendation of treatment (Root Canal Therapy or extraction) based on the oral examination findings of discolouration, not based on radiographs.

HERE is why:

IF you radiograph a discoloured tooth and it DOES have signs of non-vitality you have only increased your certainty of non-vitality from ~90-93% to 100%;

Similarly, IF that discoloured tooth has a normal radiograph WITHOUT signs of non-vitality you have only reduced your certainty of non-vitality from 90-93% down to 80%.

So pleaseeeeee do not just “watch” these teeth – educate your pet owners are the facts about discoloured teeth and let’s get them TREATED!


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 About the Author: Amy Thomson, DVM, DAVDC

Dr. Amy Thomson is a dentist and oral surgeon, and completed her residency at University of Wisconsin-Madison. Prior to pursing residency, Amy started her career as a general practitioner. She finds that unique experience helps her provide guidance and knowledge that is helpful and applicable for general practitioners that want to provide the best oral care!


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