They pull it because thats the cheepest option, vs. rootcanal or crown. they told me that, "well do you have $3,000 bucks? if not just get it pulled."
I've had 3 root canals. Paid $100 for each one. It's called Dental Insurance, and is a perk of being gainfully employed in the US. It means I get to keep my teeth, which helps me remain employable in the better paying jobs. It's a viscous circle. 
They are going to drill a very large hole in the top of the tooth and dig out all the nerves and blood vessels. Then they will take little wires and picks and dig out the same from each root while taking xrays to make sure they have reached the bottom of each root. Then they will cauterize everything with a red hot poker. They will fill the hole and take a cast of your tooth. You will have to come back again in a few weeks to have the temporary filling removed and a permanent one put in. At the same time they will grind away a large amount of your tooth to leave a peg-shaped stub, after taking a mold of your original tooth. You will then come back in about a month to have a crown (created from the mold they took) placed over the stub. Once you have a root canal that tooth is devitalized (dead) and the crown keeps it from fracturing as it grows brittle over time.
This procedure can save your tooth for years or decades. Eventually the crown will fail or the tooth will fracture and you will have to have it pulled, but I think 20 years is a pretty average run before that has to happen. I had one tooth that had to have 2 root canals followed by an apicoectomy (an oral surgeon has to put into your jaw and remove bone to get at the roots from the other side) but I still have the tooth.
Good luck, and tell us how it goes.
omfg 
details on procedure are greatly appreciated, thank you!
but omfg
I didn't get a crown with the rootcanal treatment.
They did drill a hole like MLA told, but, left most of the molar intact. With a very fine drill cleaned each of the root canals. Using X-ray to make sure they were thorough indeed, and, two times I had the older dentist, he also sniffed the tiny brushes, to make sure there was no putrid scent on it after the cleaning. Then they filled it with a clove-oil smelling disinfectant substance, and put a temporary filing in.
I've had three root canal treatments. one time the infection was that big that I got a course of anti-biotics to take too. After a couple of weeks I came back, the temporary filling was removed, the roots cleaned and filled, and a permanent filling put in. That one then got polished to make it feel good.
I'm glad that I went for the procedure. Very happy to still have my molars.
One of my teeth needed the cleaning procedure twice, before the permanent filling was put in.
The procedure can be done without something as complicated as a crown. And, my teeth look and feel good.
MLA is right, it is not painful.
You'll get a local sedation, if needed. But, if the dentist is sure all nerve-ends are already dead because of the infection, it can be done painlessly without sedation. If there is even a bit of the root alive, you'll be sedated. (I'm scared shit-less of sedations, so, I've had two of them without, without a problem.)
