Dear Christine,

I wonder if you could advise whether there is anything that I can do for my dog, Zac. A couple of days ago I noticed that one of his canines has turned a light shade of pink/grey. I went to see the vet I normally go to and he said that the dog was not in pain (because he did not flinch when the vet pressed his tooth), that there was no infection/abscess, that the gums looked nice and normal and that he probably has cut the blood supply to the tooth by banging it into something hard. When I asked whether root canal therapy would help, he said that he would not recommend it. However, I am concerned that the pulp and nerve will get infected at some point, if they
are dead.

We care about Zac and if, in the long term, root canal therapy would prevent the tooth from becoming infected, I would come with him to have it done. I would really appreciate your advice on Zac’s options and outcome if he has something done and if not.

Thanks,
Alison

DR. CHRISTINE’S REPLY:

Dear Alison,

Thanks for your email, this is something that I do get asked a bit so you’re not alone in your confusion.

Basically, if the tooth is discoloured from the inside, there is significant bruising of the highly sensitive pulp tissue inside the tooth.
If this is fairly widespread over the tooth, it is highly likely to be dead inside (a study published in Canada looking at these teeth found something like 93% were dead). This is because compression and swelling causes the pulp tissue to die (like a brain injury within the skull, the tissue can’t expand within the hard tooth, so the pressure builds up and the cells die).

The cases which MAY be still alive tend to be either in very young dogs where the root of the tooth is still growing (these have an open root so the pressure from swelling can be relieved more easily through the opening), or in teeth where there is a very localised patch of
discolouration (as the rest of the tissue may survive and repopulate the injured area).

If a tooth is dead and filled with dead tissue, this is like a sitting time bomb for infection. Bacteria from the body like to find their way to dead tissue (it is so tasty for them!!). Once they get into the tooth, antibiotics can’t reach them so they cause chronic infection.

It is impossible to predict when this happens by looking from the outside. Once the tooth is dead, the nerve dies so the tooth isn’t sensitive to touch. In humans, dead teeth are often painless as long as they don’t get infected (my 3 year old son has two black and grey front teeth from where he smashed them into a table while trying to fly like a superhero – they really hurt for a week or two, but now don’t hurt at all). However if they do get infected, he will let us know as they will hurt like crazy, and then we will know we need to see the dentist again.

The problem with dogs is that they don’t like to tell us when they have a sore tooth. As pack animals, they instinctively hide their pain, so they don’t appear weak or unable to pull their weight with hunting. This would lead them to being demoted in the pecking order, or thrown out to fend for themselves. I have seen teeth ripped in half by whipper snippers and chainsaws, with the nerve hanging out, that were intensely painful, yet the dog acted ‘normally’ and even ate dinner.

So without Zac telling you if/when it gets infected, you are really playing a waiting game, he will tell you when it is excruciating, but not until it becomes so sore that he cannot physically eat. The infection is deep in the jaw (for a canine the end of the root is about 2-3 teeth further back in the mouth) so you rarely even see any swelling.

Basically the two options come down to:

1. Wait and see – but as he may be infected without us knowing, I’d highly recommend monitoring it with dental xrays over time so we can detect deep infection in the jaw if it occurs. This requires an anaesthetic each time to take the xray. Xray changes in these things can also lag weeks to months behind, as you need to lose a fair amount of the bone due to infection before the xrays can detect the change in density. Therefore Zac may be sore for a period before we can tell.

2. Treat on the assumption that it is highly likely to be dead, and has a fair chance of getting infected at some stage. The options would be extraction or root canal, both procedures remove the dead tissue so the mouth can heal, obviously extraction means there is no tooth there, while root canal preserves the tooth. We can work out the best option for Zac when we see him.