Do I really need this crown on a root canal tooth?

Hi, Dr. Hall,

I had a root canal done on a molar almost 5 years ago. After the dentist did the canal he put in a filling which has recently come out. I went back and he has told me I need a crown put in with posts, I was wondering if this is necessary rather than just getting another filling? What are the pros and cons of crowns? and is it strange that he didn’t originally put in a crown as there’s not much of the tooth left and I think he probably would’ve known the filling wouldn’t last. Any help would be great as I really don’t know what to do.
Thanks,
Melissa from Ireland

Melissa,
The only puzzling part of your situation is why the dentist didn’t recommend a crown when the root canal was first done. Now you’re in Ireland where much of the dental care is publicly funded. I’m wondering if that has something to do with this.

Not every tooth that has a root canal treatment needs a crown. I’ve written before on this blog about the need to be careful in doing crowns on front teeth that have root canal treatments, as a crown will weaken a tooth against lateral stresses. But practically every molar with a root canal treatment does need a crown. The reason is that once a tooth has a root canal treatment it tends to become more brittle over time and more susceptible to breaking. Molar teeth in particular are the most susceptible of breaking in this circumstance for two reasons. They are the teeth furthest back in the mouth, so they receive the greatest chewing pressure. Furthermore, because of their cusps, the stresses on them tend to separate the cusps, which subjects them to a high risk of cracking in two. A crown will protect the tooth against cracking in two.

So yes, I would do the crown.

And a post or posts would be needed if there isn’t much of the tooth left to hold the crown on—if the tooth is mostly filling. Otherwise you wouldn’t need a post.

– Dr. Hall

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