There are two types of wrinkles: dynamic and resting. Dynamic wrinkles
form when muscle is contracted but resolve when the muscle is relaxed.
For example, a child who raises their eyebrow or furrows their
forehead has lines on their skin only if the underlying muscle is
contracted. As people get older, these dynamic wrinkles start to
create permanent folds in the skin. Sun damage also contributes to
this skin change. In older people, the forehead lines are always
present. Botox can be used when wrinkles are dynamic in younger
patients. It is reasonable for a thirty year old to get botox on the
forehead in order to avoid permanently etched lines on the forehead
and crow's feet area.