This question is one that we get, probably, more often then any other.
Below is a picture from a patient that we saw for the
first time yesterday. You will notice that towards the
top of the picture there is a chip out of the tooth.
The tooth has a large metal filling already and is in a weakened state.
How long this tooth will last till it suffers a more significant break is
almost completely up to the patient.
If the patient went on an all yogurt diet then the tooth would last a long time.
If the patient had a corn-nut addiction it may last 12 hours.
There is really no way to tell.
Best thing to do is obviously to get it fixed.
But if you can't then the best thing is to make sure that you
don't chomp down on anything really hard on the side until
you can get it fixed.