Fat infection does not replace collagen, while fat works better for large indentations and sunken areas, collagen works better for fine lines, frown lines and wrinkles. The end result is far more accurate with collagen, but also more temporary.

Fat shrinks 30 to 50 percent after injection whereas Zyplast collagen doesn't shrink at all. It is replaced by your body's own collagen to some extent. You should have a skin test in the arm one month before having a collagen injection.

Wrinkles caused by continual muscle folding will, of course, tend to come back. Static deformities (not caused by muscle action) generally do not return. You can have a wrinkle filled in at noon and be presentable in public that very evening.