ArteFill, Silikon 100 or PMMA?

Long term and permanent fillers are very desirable for obvious reasons. The only PMMA approved in the United States is Bellafill, despite many past issues with this filler, it has a very excellent safety profile now and is FDA approved. Silicone is an off label use and has more potential long-term issues.
I would say it is also worth considering fat transfer, as this is also a long term or permanent option that comes from you! Fillers like sculptra and radiesse also have an excellent duration, but are not permanent. 
No matter what, with a longer term or permanent option, make sure you are seeing a true expert in pan facial volumization. 
To ensure you are receiving the highest level of care, seek out a modernly trained, new-school dermatologic surgeon, oculoplastic surgeon, facial plastic surgeon or plastic surgeon who is board certified and fellowship trained in one of these "core four" cosmetic specialties. Membership in organizations like the American Academy of Facial Plastic and Reconstructive Surgery help to identify a highly trained surgeon.
Cameron Chesnut
#realself500 Physician

Aretfill is a great treatment if injected properly. There are a lot of options for improving the nasolabial folds and cheek volume and this often means fillers for the folds themselves but also lifting around the mouth and cheeks to build underlying anatomical support and volume. In our practice we combine sculptra with other fillers "layered" on top and lasers, rf treatments and peels to get the most conservative natural look. Please see a facial sculpting expert. Best, Dr. Emer

This is an excellent consideration. Making the wrong choice can result in a long history of problems.
I practice in Southern California and Las Vegas, NV. It is against the law to inject Silikon in Nevada. And, there is virtually no other medical severe prohibitions than this in Nevada.
I have treated numerous women who had liquid silicone injected into the lips that produced a chronic inflammatory response (about 4% of patients) and produced enlarging lips, hard lips, and deformity of lip movements. This treatment is to excise all the inflammatory tissue containing the silicone, like dance surgery. After the surgery heals, then lip augmentation is contemplated and performed, usually with a soft silastic lip implant (Surgisils Permalip). 
Bellafill can be injected in all facial anatomical sites, excluding the bulk of the lips. If patients request a permanent lip augmentation, soft silastic implants are the recommendation.
Facial volume loss can be treated with either silastic facial implants, facial fat transfer and Bellafill dermal filler, the only filler approved by the FDA for this purpose. The advantages of the silastic implants are that they can lift or suspend facial tissue, fill in the volume loss, and compress some of the acne scarring.
Fat transfer has stem cells and growth factors to further improve the quality of the skin as well as fill in volume loss.We performed a study in five patients with acne scarring and volume loss treated with fat transfer and the acne scarring appearance was improved by 50% even prior to the Laser skin resurfacing procedure. The stem cells and growth factors are the most probable reason for this and a significant advantage for volume replacement in acne scarring as well as the placement could be used in all areas of the face.
Bellafill is excellent for minor areas of volume loss, however, given the amount of volume replacement needed, this can get expensive since each syringe costs about $950. I prefer to use a microcannula for placement to minimize bruising, pain and lower risks of vessel injection.
There is no treatment for excess liquid silicone injection except surgical excision. If there is excess Bellafill injected or granuloma formation, 95-99% of patients can be successfully treated with Kenalog.
In summary, I strongly recommend NOT using Silikon. The other permanent options (silastic implants, fat and stem cell transfer, and Bellafill filler) should be considered with one recommendation better than another based on the anatomical site(s) to be injected and the amount of filler to be injected.

You are wise to seek out a filler that is long term.  The short term fillers can give great results but many patients get tired of the repeated injections, decide they do not want the pain or hassle or repeated injections or simply decide they do not get benefit they expect from the repeated cost (credit card fatigue).  Artefill is now known as Bellafill and it is a PMMA based filler.  In the US, Bellafill is the only FDA approved PMMA based filler.  This is for good reason, the other PMMA based fillers available in places like Mexico and Europe can have some pretty significant complications.Silikon 1000 is liquid silicone that is available for retinal surgery.  It is used by some physicians off label to treat facial wrinkles, it must be used by very experienced injectors as there is an array of complications that can occur with this product including a problem called beading, which is a series of small lumps that will occur if Silikon 1000 is placed too close to the skin.Bellafill will produce a smooth natural result and because it can be placed close to the skin, very minute corrections can be made.  I have added a web reference and a video about Bellafill for you.  I hope this helps.Best regards.