Cheek Implants and Nasolabial Folds

The situation you describe is consistent with the unfortunate aging process. As we grow older, the soft tissue of the cheek sags downward with the force of gravity. Because of tethering of the skin to the deep structures of the face at the nasolabial area, the drooping tissue forms a fold and shadow at the nasolabial crease.
Increasing volume in the cheek area can help this a bit, and alternatively fillers placed to the crease can bulk it up and reduce shadowing. Unfortunately, while both of these procedures improve the symptom of the shadows at the nasolabial fold, neither looks natural or mimics the look of youth.
Literally yesterday I saw two sisters who both came in for Restylane in their nasolabial creases. Both had previously had this procedure performed by another surgeon, and complained of a firm ridge at their nasolabial area. I explained that further injection of foreign body to this area is certainly possible and popular these days, but did not tend to look youthful or natural. I instead showed them how, when a lifting of the soft tissue of the cheek back to its proper position over the natural cheekbone is performed, the entire mid-face is rejuvenated, and the shadows of the Nasolabial fold are improved in a natural appearing manner. Both women decided against further injectables and are planning on getting this more natural appearing, more permanent solution.
I would suggest discussing with your plastic surgeon a cheek lift performed through a lower eyelid incision- this is frequently combined with eyelid surgery and this may be an option for you as well.

A small cheek implant placed in the submalar area can have a slight softening effect in the upper portion of the nasal labial lines. The nasal labial lines are best treated with either fascia grafts harvested from behind the ear (done at the same time as a facelift) or a simple injection of Restylane type fillers in the nasal labial folds.

Yes a cheek implant can not only augment your cheeks but can also help with the prominence of the nasolabial fold. An alternative approach is to perform fat transfer to your cheeks. This will produce a similar result to the implant but will use your own tissue. It typically loks more natural, especially as you age.