Implants are used in a multitude of applications to correct volume deficits. The most common implants in plastic surgery are breast implants and are discussed here (link)
Other implants have specific use. Most are made of Silicone or Goretex® and have many different formulations and costs and can be ordered in standard shapes or can be custom molded based on a template or radiographic imaging to fill in defects. Medpor® is a porous, high density polyethylene which allows in-growth of structural and vascular tissue which stabilizes and protects the implant. Alloderm®, an example of an acellular cadaveric dermal graft can be implanted for augmentation, correction of soft tissue deficits, or structural reconstruction.
Frequent uses for acellular dermis include lip augmentation where it is inserted under lip mucosa, filling in areas of atrophy or depression, and correction of surgical scar depressions. Acellullar dermis acts as a matrix and is ultimately vascularized, infiltrated, and incorporated by nearby cells. Infection, migration, and extrusion are not a significant problem with acellular dermis, as opposed to permanent implants.