Also see the threads on swishing. I've just started trying this out today after reading about it. My gums and teeth were achy all day, and within 30 seconds of starting swishing the pain went. That was 8 hours ago now and the pain hasn't returned :)
I've stopped using toothpaste with Fluoride in it as I believe that can make the gum problem worse and now use the old-fashioned Baking Soda (or Bicarbonate of Soda as we call it in the UK).
I think if we are honest, most of us have neglected our teeth at some time. I know I have in the past. I have some pretty bad gum disease affecting my lower front teeth - one of these days I'm going to wonder what's crunching when I eat something!!! Don't think my front tooth will make a tasty morsel LOL.