“I understand DYMAX has a masking material that is biocompatible or had biocompatible testing done on it?”
DYMAX provides a selection of adhesives (http://www.dymax.com/products/medical/index.php) that have been tested according to ISO 10993 and are biocompatible in the cured stage.
A medical-grade material is typically not needed for temporary masking applications where the light-curable resin acts as a manufacturing aid only and is being removed before the end product is finalized.
"Is there a UV-curable adhesive that when cured conforms to USP Class VI and passes ISO 10993 requirements for permanent implant?"
Unfortunately, not that I am aware of. Technically, most light-curable adhesives are acrylated urethanes or epoxy-based systems, and would not survive permanent implantation. There are other hybrid light-curable technologies, but as far as I know none have been released technically for long-term implantation. In addition, the legal liability is too high for most applications. Perhaps something from the dental cement industry might be a suitable option.
"Are methanol, ethanol, acetone, or acetonitrile FDA approved?"
These solvents are generally not FDA approved. These particular solvents bond plastic together by melting the plastic, and then allowing the plastics to intermingle. As the solvent evaporates, the plastics harden to form a strong plastic weld between the plastics. The choice of which grade of solvent you buy is up to the medical device manufacturer (higher purity equals higher price). Since solvents evaporate and do not remain in the bond line, they are not normally tested for biocompatibility.