I have recently consulted with my dentist about a molar that has been causing me quite a bit of trouble. It was root canaled, and before that was filled twice because it acted up underneath the original filling and had my entire face all swollen up. The tooth had not hurt after the root canal, but recently half of the tooth broke while I was eating a club sandwich. The tooth does not hurt at all, and I told my dentist I would like it extracted. The wisdom tooth on that side had already been pulled years ago, and yet my dentist said he would not recommend pulling the tooth. My understanding is that dead teeth need to be pulled, why is my dentist so reluctant?
Extractions are probably the most sensitive area medically speaking, for a dentist. We dentists have taken an oath to do whatever it takes to preserve human life, health and well being through the means given to us, and we specialize in keeping teeth in the mouth and functional for as long as possible. That is why the idea of pulling teeth is abhorrent, like the idea of an amputation for the surgeon; a worst case scenario to be avoided at all costs, unless absolutely medically necessary. This is why your dentist is so reluctant to pull that tooth.
Essentially, your dentist has told you that it is not medically necessary to pull the tooth, and there could be a myriad of reasons why s/he chose to do so. Even though dead teeth are usually pulled, there are reasons why you would want to keep the tooth in for a slong as possible, even after its death, particularly if the tooth is not infected.
First off, the tooth may not be dead. Just because the tooth is discolored does not mean that it is dead. In the case of root canaled teeth, sometimes blood can get in the pulp chamber when the pulp is being removed, and this can make the tooth appear reddish, brownish or even black. You can restore the tooth to its original cover with an internal whitening session, and if the tooth is indeed still alive, it will look as good as new.
The other reasons can be considered functional issues. While the tooth may be dead, and although half of it may be missing, it may be in a location where it is fulfilling an important function in biting or chewing. Seeing as this is your hindermost tooth, you are probably using a good deal to chew your food, this maybe the reason it needed to be root canaled initially, and this may also be the reason it ended up breaking. To remove it may tax the joints in your jaws by forcing you to chew on the opposite side more.
Finally, the main reason dentists tend to avoid extractions is because tooth loss is a medical condition and missing teeth weaken the oral environment. The alveolus is a crest of porous bone and ligaments that is beneath your gingiva, on top of your jawbone, essentially fused to it. Once there are no tooth roots in the alveolus, it starts to disintegrate and weaken. Disintegration at one point will cause the teeth next to the tooth that is missing to become looser, and eventually to fall out entirely. This is why sometimes it is better to keep a dead tooth in the mouth for a bit longer. I believe your dentist, after seeing your tooth decided that the dead tooth will probably not become infected or rotten within the next six months, when it is time for a check up anyway. If the condition of the tooth gets worse, it can be pulled anytime. If you are unsure of your dentist, maybe it is time to get a second opinion from someone else.