We received this tip video from the Seattle Study Club in their Sep 2017 email:

The only thing we would like to add is that not all surgical guide materials are created equal.  Because of the temporary nature of a surgical guide, a lab can pretty much choose to use any clear or semi-clear biocompatible fda listed resin.  However, some cured resins tend to slowly disolve while exposed to isopropyl alcohol, so an IPA bath for 15 minutes in an ultrasonic cleaner could impact the dimensional stability of the guide, again depending on the material used.

Micron SG resins are resistant to disinfectants and can also be sterilised using gamma rays and autoclave. The use of an autoclave does not affect the dimensional stability so Micron surgical guides can be used in every operating theatre.