PMMA Filler for Jaw, Cheeks and Chin?

I would not advise using a Permanent filler such as PMMA in your face. Although the idea of having something permanent injected is appealing, it may cause problems that are hard to correct.
Foreign body reactions such as granulomas are not uncommon and manifest as lumps, redness and pain. Fillers such as Artecoll and ArteSense have been widely used and have had mixed results. They have been mostly used for filling of facial wrinkles and lines.
Very large amounts of this material would need to be injected in order to create any visible change around the jaw and chin and I would not recommend this. The only "permanent" filler that I would use in such a case is Bio-Alcamid (a poly alkyl-imide gel) that works as an "endoprosthesis" by forming a capsule around the gel and thus not degenerating and disappearing.
The advantage is that very large volumes can be injected and it can be removed with relative ease if need be. Unfortunately, this is not available in the U.S.

PMMA is cement. Cement used to anchor hip joints into the bone. Would you really want this in your face, even in small amounts?? If anything goes wrong ie. lumps or bumps or a late infection, the material is almost impossible to remove, at least without conspicuous scars. Use the temporary fillers, some can last a few years and can be modified as your needs change as you age. This is the smart way to go!