Expression lines come from doing the same thing with your face several million times. Frown lines from concentrating, crow’s feet from smiling and squinting, forehead lines from raising your brows.
The distinction that matters is dynamic versus static. A dynamic line appears when the muscle contracts and disappears when it relaxes. A static line is visible at rest, because the skin has been folded so often that the crease has become permanent.
Dynamic lines respond well to muscle relaxation. Static lines improve beautifully when the skin is treated as well, because the crease is now in the tissue as well as the movement.
That is also the argument for treating earlier rather than waiting. Relaxing a muscle before its line has etched in can help keep it from settling, so starting early keeps treatment simple.
Regents Park Aesthetics treats these at our Wimpole Street clinic, a short walk from Oxford Circus. Your clinician shows you which category each line falls into, and pairs muscle relaxation with skin treatment wherever a deep static crease needs both.