Apparantly there was nothing I could have done to prevent the wisdom tooth from going bad, I do need to have it out (getting that done in a fortnight or so) and the bad tooth caused a tiny bit of decay on the tooth beside it, but that's it. He basically said (without kidding) that once I got this done, it would probably be another 15 years before I needed anything done, barring accident.
So they cleaned out the tooth, drilled it and put in some antiseptic and a temporary filling to tide me over until it comes out. They're a real professional bunch and I didn't feel a thing the whole time except the scraping and pressure (which freaked me out less than it should have). They're in fitzwilliam house on fiztwilliam st (under fitzwilliam hse dental surgery in the yellow pages) and I'd reccomend them to anyone (at least until the tooth is pulled and I cry for a week)