Methods of forming antimicrobial resin compositions comprising silver nanoparticles are disclosed, wherein the resin compositions that are generated exhibit lower initial color, reduced color shift upon storage and reduced levels of spontaneous polymerization. Such methods generally comprise: combining a silver-containing material with a self-cure and dual-cure base resin in situ wherein the base resin does not contain a catalytic amine; and adding a catalytic resin to the mixture of the resin and silver-containing material in order to form the final cured resin. Antimicrobial polymeric materials formed by said methods are also disclosed.