Re: Root Canal Questions - 1st one kind of urgent
1) Molars should be crowned rather quickly after a root canal, in my oppinion. I know plenty of people that have had molars that were not crowned at all and have no problem, and I have known people who have tried to wait a few months and have the tooth crack. A couple of things to consider when making this decision:
1) what was the condition of the tooth before the root canal - was it fairly strong with good bone around it; did it have a large filling in it that would cause weakening of the tooth before the root canal?
2) what is the size of the filling in it now - fillings weaken the tooth if they are big, so if a great deal of the crown is filling, it is at risk of chipping.
3) Do you have any oral habits that may stress the tooth a lot and put it at risk - clenching and grinding, crunching ice, biting hard candies, and even chewing gum, as the filling in it is probably just a temporary.
It takes a while for a relatively healthy tooth to become brittle after root canal. Therefore, if the tooth was strong before your root canal and your teeth in general are of relatively good quality (you don't have genetically weak teeth), waiting 4 months should not be a problem, though there is a risk. I think as long as you feel you are a good candidate to wait and you are careful not to stress it way too much, you will be fine.
As for the types of crowns. First, there is a small amount of mercury in metal fillings and crowns. There are a very few people that are mercury sensitive and they have a problem with mercury in dental restorations. These are the cheapest types of crowns and really they are quite good and will probably cause you no trouble what so ever. Gold crowns do not contain mercury, nor do crowns made of all high noble metals. Porcelain and porcelain fused to metal do look better, particularly in the front, but they are not as strong as the different metal types. Personally, I think the metal ones would last you much longer and carry less risk of cracking or breaking. It will not show in the back, so metal really is a good way to go, unless the look really bothers you.