i know perfusionists make pretty good money, especially with calls and what not. To leave that job completely and pursue dentistry seems like a risky movement. Not saying you won't get in, I think it would be wiser for you to work for a few more years, save up as much as you can (spending only a bare minimum), then start taking classes. I am not sure what classes you are planning on taking, but I am guessing you are trying to retake some science courses and more upper level courses? or prereqs that you haven't taken?
Also, doesn't your hospital have some kind of education assistance for benefited employees? You can also think about doing part time, and get at least some education benefits.
That science GPA is going to be the biggest hurdle for you, take only as much classes as you can handle. I've seen people taking lots of upper level science in 1 semester in hopes of redeeming their bad GPA, but a lot of them actually did badly and shut the door for themselves completely.