The material may be, but what about the process? And the process dictates the hardware. The 510k submission will specify what hardware was used to demonstrate substantial equivalence to an already approved marketable device. How does the FDA know that your Formlabs printer will cure the resin substantially equivalent to the way (say) the NextDent 5100 does? Without a 510k and accompanying documentation, it doesn't.
Ask Formlabs about this specifically? "Is the part that we make with the material you sell us, when used in your printer, an FDA approved Class II medical device?" Don't ask a salesperson, ask technical support. Or better yet, ask someone like Tim Torbenson at evo820.