Basically, when I was about 15/16 I had really bad toothaches, like the ones you get when your face puffs out (aside from the actual puffyness), and eventually it was so bad and I had work at that point, I saw a local dentist and had it filled (man did that drill the absolute hell out of my gums, and those stupid needles didn't work.....).
Anyway, I'm also 22 now, the filling wore out in barely a year, the tooth has chipped and cracked to a point that there isn't too much left (but it won't fall out on it's own or even if I try to persuade it
It's also practically hollow (I just showed a family member and they confirmed it), as I have noticed lately that when I use tweezers to remove any food like meat and things from it, to keep it from becoming infected, that it is becoming quite black inside, which also when they told me it looked pretty much hollow.
When money is a big problem, I really have no idea what to do about it, and I have heard some rather disconcerning things lately linked to leaving bad teeth like I have (with bacteria build up and such causing problems).
Any advice at all?

