Among the injectable filler materials Dr. Maas offers at The Maas Clinic in San Francisco, Restylane® is one of the more commonly requested and administered. In fact, Restylane® is the world’s most used, most studied dermal filler, and has been used in over 70 countries and in more than 1.4 million treatments in the U.S. Restylane® – and the newer addition to the Restylane® family of products – Perlane® are injected in much the same fashion as Collagen but do not require a skin test, as no allergic reactions are expected. Results are immediate and natural, and ‘downtime’ is usually only a few hours.