Question.

Is it permissible to mix polymerized methyl methacrylate with the monomer, when making an embedding medium for undecalcified bone?

Answer.

Using polymethylmethacrylate powder or beads does not affect the polymerization process, but it does make the preparation of the partly polymerized embedding mixture easier and safer.

You may care to refer to the following paper.
Difford, J. (1974) "A simplified method for the preparation of methyl methacrylate embedding medium for undecalcified bone." Medical Laboratory Technology 31: 79-81.

John Difford
Royal Free Hospital
London, England.
(adford[AT]compuserve.com)