cosmetic filler that can be used to restore facial volume lost due to contains poly-L-lactic acid (PLLA), a biocompatible synthetic substance that stimulates collagen production. cosmetic filler that can be used to restore facial volume lost due to contains poly-L-lactic acid (PLLA), a biocompatible synthetic substance that stimulates collagen production. cosmetic filler that can be used to restore facial volume lost due to contains poly-L-lactic acid (PLLA), a biocompatible synthetic substance that stimulates collagen production. lines between the mouth and chin) and nasolabial folds (smile lines or laugh lines). lines between the mouth and chin) and nasolabial folds (smile lines or laugh lines)..syi