Aesthetic applications of calcium hydroxylapatite volumizing filler: an evidence-based review and discussion of current concepts: (part 1 of 2).

Calcium hydroxylapatite filler (CaHA; Radiesse) is a synthetic, non-animal derived product composed of minerals that occur naturally in bone and teeth. Following its development in the US, initial approval by the US FDA for non-aesthetic indications and CE marking in Europe, it was used off FDA-labeling for aesthetic purposes. Its use has grown further since its FDA approval in 2006 for long-lasting correction of moderate to severe wrinkles and folds. It is a popular filler for volume restoration to the face, and also to nonfacial areas such as the dorsum of the hands.The first article of this two-part series provides an evidence-based review of study data pertaining to the mechanism of action and biocompatibility of CaHA filler, and its safety, efficacy and tolerability when used for aesthetic purposes. The review includes data from a number of prospective, controlled comparative studies, from several retrospective studies, and from a meta-analysis of reported complications from alloplastic filler procedures over a 20-year period. The study methodology and number of study subjects are sufficiently robust to provide a high Evidence Level for much of the data.CaHA has good safety, efficacy and tolerability profiles that are comparable to those of hyaluronic acid (HA) fillers. It provides an initial, immediate volume replacement for up to 12 months followed by longer term correction due to biostimulation, resulting in collagenesis. Evidence Level II studies show longevity of 30 months or more after nasolabial fold implantation. Other studies demonstrate the appropriateness of CaHA filler for volume restoration to areas including the mid face, lower face and hands. CaHA is classified as an adjustable filler, whereas HA is fully reversible by hyaluronidase digestion. For this reason, and also because of CaHA's high viscosity and elasticity, evidence-based and experiential consensus suggests its avoidance in highly mobile areas (e.g. lips) or in anatomically unforgiving areas (e.g. the periocular region), where there may be increased incidence of nodules.CaHA filler is safe, efficacious and well-tolerated when used appropriately. It is increasingly recognized that many patients require pan-facial volume restoration, and that many can benefit from combined treatments. Therefore, CaHA and HA fillers may be considered complementary rather than competitive to each other. The second article of this series offers a discussion of product characteristics, scientific principles and injection techniques to optimize treatment with CaHA filler, including special considerations for avoidance and management of complications.