9.4.1.3　Poly（lactic acid）（PLA）

PLA is a volume stimulant，instead of a direct filler.Unlike HA，one of the advantages of PLA is to stimulate the production of collagen to maintain the anti-wrinkle effect for a long time.However，the injection of PLA may produce subcutaneous papules，which requires a small amount of multiple injections.The frequently injected area is the cheek，chin，temple，etc.and fan-shaped injection is conducted in this area.Yet，it is impossible to predict the possible effect since it is not a filling material，so the amount of injection needs to be controlled.(https://www.daowen.com)