The smoothing threads are loaded onto very tiny needles which introduce them into the subdermal region of the skin around the lips. They are placed close together in “rows” to stimulate maximum collagen response over time.  PDO Lip threads are loaded onto very thin microcannulas, which are dull tipped but otherwise similar to the needle loaded threads. They are introduced into the border of the lip, usually 5 in total, and are more expensive due to their special design and longer length.