Dear Lyari, Let's use the Socratic method. Does Polymethyl Methacrylate really BELONG in the buttocks? If so, why didn't God or Evolution (you choose...) put it there? For those of you who do not know, PMMA (Polymethyl Methacrylate) is an epoxy-like cement widely used to fix and secure orthopedic (knee, hip, shoulder) joints in bones. PMMA comes in powder form and when mixed with saline solution (and any antibiotics you may), it becomes a sticky honey-like gel which gives off heat and sets into a stone hard cured concrete which will hold anything in place. PMMA has ALSO been used to fill in bony depressions on the skull and forehead as well as temporarily fill in bone defects (trauma, cancer, infection) while the surgens wait for swelling to go down. Placing PMMA in the buttocks will result in an unnatural feel AT BEST, even if sand like particles are used. Putting larger PMMA particles will be analagous to sitting on pebbles or rocks. As with other fillers containing PMMA, no names mentioned, it will be hard to remove and occasionally will find its way to the surface with small holes chronically draining sandy particles.