I don't believe oil pulling does anything significant as far as chelating metals like mercury.
I have a tooth where a filling fell out so long ago it's ridiculous. Instead of going to the dentist I just keep putting in this temp filling compound I get from the drugstore. But more times than not it gets sucked out when I oil pull. This isn't due to chelation since there's no metal in the temp filling - but just to the oil viscosity and swishing action.
Also I've done chelation before and the metalic taste of my fillings as they were dissipating was very strong for days. Never experienced any such thing with oil pulling, and never heard anyone else mention it.
That said, the question of whether chelation is a good or bad thing if you have metal fillings is hotly debated around here.
Most say never ever do chelation if you have metal (mercury) fillings because it will cause the mercury to start and continue to leach out. As if you're somehow throwing the switch of a pipeline to the Mercury in your filling that can't be turned off.
I dunno. Personally I felt amazing when I did the chelation even with an entire mouthful of mercury fillings. And a week or so after doing the chelation the metalic taste of my fillings did go away.
My body felt so clean, energetic and renewed. This sounds strange but the sensation was as if someone replaced all my salty blood with fresh water blood. Weird, but that was what it felt like in a nutshell.
If the Chelation weren't so expensive I'd continue doing it often - although I do continue to take chlorella.
I personally believe the proof of natural medicine and healing is in how it makes you feel. And theories aside, chelation really made me feel great, and it's not like anything adverse happened after the fact.
(If you're interested you can find the oral chelation product I used at extremehealthusa.com)