How to handle a cracked tooth

[Paxiled]

I've been having these amorphous pains in my mouth, and after a cavity was filled in this tooth it hurts to bite on it.  I went to see a different dentist because the one I've had for a long time just doesn't seem to be able to ever properly diagnose what's going on with me.  I saw my wife's dentist and was diagnosed with a cracked tooth  -- he used a powerful light to show me how it was cracked.  He offered me two solutions -- a crown, which he said was only a 50/50 proposition, or the better option, get a root canal and in that way learn how far down the crack is and whether the tooth can be saved (it's a longitudinal crack).  What I don't understand is, how can a root canal save a cracked tooth?  It will still be cracked and even more brittle (I've already lost three teeth that had root canals to infections and cracks).  Can you explain how this will help save the tooth?  

[Jerome Tsang, DDS]

Cracked teeth are the worse in terms of predicting success of treatment.  I think that's where your confusion or difficulty in deciding comes from.  No one really know exactly where the crack is.  So without knowing, we don't know what type of treatment is required.  On top of that, cracks are small so sometimes you can't see how far it goes so results are more unpredictable.  You could try the conservative route and see how it goes if you're willing to be patient.

[Paxiled]

Sorry, confused the side of the mouth there -- lost two on the top left, this one is on the bottom right next to two other teeth with old root canals.

[Paxiled]

So what's the best course of action?  The conservative route, just getting a crown and still having a live tooth?  Killing the tooth with a root canal, which might or might not find the crack and how deep it goes but the best outcome is a brittle dead tooth still, I assume, with a crack in it?  I guess I still don't understand the best way to go.  A root canal will give me three in a row on the bottom left, I just had that situation on the top right lead to two cracked root canal teeth and two extractions and nothing yet in their place because the first extraction took over a year to stop hurting for unknown reasons.  I need to eat, so I'd like to save the tooth, but obviously don't want still another root canal tooth if I can help it and certainly don't want another extraction but I'm still quite confused on the best course of action.  Thank you again.

[Jerome Tsang, DDS]

The root canal doesn't guarantee that the tooth will be saved either.  It depends on how deep the crack is.  By doing the root canal, we can access the area and take a better look at how deep the crack goes.  If we don't do the root canal, then we try to avoid getting near the pulp chamber where the nerve is, but at the same time, we don't access as much since we're trying to be more conservative.  There's a possibility that once they access it, the crack may be too deep and the tooth will need to be removed.