The filler revolution: a six-year retrospective.

There are currently more than 20 FDA-approved fillers in the United States (U.S.), noteworthy considering that it was only six years ago that the first hyaluronic acid filler was approved. The pace of development of filler substances in the last few years has been extremely rapid. The authors review the development, advantages, and disadvantages of fillers currently available in the U.S.