Whatever you do...... don't go cheap on the lens and flash !!! D80 works well also. You can always find used equipment as described earlier......D200(used) works awesome also and you can find those from people that always want to upgrade. The most important factors with the Nikon's for dentistry is:
1)exposure control(ttl) 2) colour balance 3) depth of field control.
You always want to shoot in Aperture Priority. The Nikon D80-D300 allows very high F-stops at those macro distances that allow you to see anteriors better than a High Def TV.
shots with a 32 F-stop yield incredible depth of field.
Invest in the 105mm Nikkor lens and R1 flash (don't need C1 component for dentistry),save the $$$ if you have to on the camera body. When buying used cameras, ask the vendor to send you a few images of blue sky taken with the camera. Check the images for repeatable dark spots from image to image. Internal sensor may be damaged.
Great Photography yields Great Business !!! The photography should pay for itself within a few cases.
I'm on vacation til the 28th. Back in trenches that Monday. Post your email and I'm happy to send you my Nikon camera settings and photography protocol.
, James
ps. Load those amazing images onto Microsofts Skydrive and view them with an iPad for build ups and Q.C. ..... stunning quality!!! Your doctors will be blown away!!!