Collagen substances.

Soft tissue enhancement has become increasingly important as more patients seek aesthetic improvement without major surgical procedures. Injectable Zyderm bovine collagen has come to be regarded as the "gold standard" of injectable or implantable fillers, against which all other fillers are measured. This article describes the techniques of injection for bovine collagen and discusses the indications, allergenicity, and adverse responses. Other types of available collagen substances are also discussed.