Will i go for false teeth or not?

2 of the lower jaw molars was extracted.my dentist told me that i should have false teeth because those upper molars which doesnt have partners at the bottom will extrude and expose their roots in due time.is it true or she just want some money out of me?

Sounds a little fishy. I'd get a second opinion.

She is correct. The teeth will eventually try to fill in the gaps themselves causing spreading and loose teeth

Yes, when a tooth is unopposed they will usually begin to grow towards the empty space. Their roots my not become exposed as the bone will usually grow down with them, but by hanging down below your other teeth they will begin to cause food impaction and eventually a gum problem. Many a time I've had patients finally decide to do something after the teeth have extruded and then it's a MAJOR problem to bring the teeth back into alignment with crowns, as usually a root canal has to be done also. It's a lot better to bite the bullet and go with your doctor's recommendation. However, your choice is going to be either a partial denture or implants from what I can gather by what you've said. A partial will NOT feel or chew like real teeth and you need to talk this over before you go ahead with treatment.

When a tooth is extracted it's counter starts to "look" for something to meet! If you lost a bottom tooth, the top one starts to drop down looking for something to meet. It will keep on dropping down, coming out of it's position in the jaw, exposing rooth surface which is very prone to decay, opening gaps between the teeth where food can impact causing decay on the adjacent tooth... Not a good scenerio.
Dentisty, unlike most medical professions, is very mechanical. Top teeth need bottom teeth to hit and bottoms teeth need the top ones.
I don't know how old you are, but we recommend for all our patients, both young and old, to replace posterior molars. They help to maintain the vertical dimention of your mouth, (you've seen old people with their faces caved in) and you need molars to chew properly.
Talk to your dentist and if you still double that she is giving you proper treatment, get a second opinion.