PMMA Filler for Jaw, Cheeks and Chin?

Thank you for the great question.  Although the concept of a permanent filler is very appealing, you must remember that facial aging is a very dynamic process.  Use of a permanent filler presupposes that you will not have changes in your face over the next 5-10 years.  Needless to say, this is a very false assumption.  PMMA is not metabolized by the body and is the same material used in various glues.  It is also associated with lumps, nodules, granulomas  and other problems for 5-10 years after injection.  Since facial aging is dynamic the PMMA will be permanent but the aesthetic result is not.

Using permanent fillers such as PMMA in the face is not a good idea. They can become hard and form granulomas that are very difficult to treat.

PMMA bone cement is used to fix implants in position and to remodel lost bone. It is applied as a dough-like cement that gradually hardens. It acts like a grout and not so much like a glue. Although sticky, it does not bond to either the bone or the implant, it primarily fills the spaces between the prosthesis and the bone preventing motion.
A big disadvantage to this bone cement is that it heats to quite a high temperature while setting and because of this it kills the bone in the surrounding area. Due to its consistency it has to be placed in position through an adequately sized incision.
Artecoll is an injectable filler that is a mixture of PMMA and collagen derived from cows. It lasts 2 or more years and may be permanent. It can be very difficult or impossible to remove if you do not like the result or if it gathers into lumps. Both forms can be hard to impossible to mold into the shape that you would want especially the Artecoll.
You are much better off with standardly used cheek, chin or jaw implants which are easier to place, easier to remove and give you a much more reliable result in terms of shape.

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!