A randomized, split-face, histomorphologic study comparing a volumetric calcium hydroxylapatite and a hyaluronic acid-based dermal filler.

[BACKGROUND] Soft-tissue augmentation with fillers is an aesthetic procedure for restoring age-related volume loss.

[OBJECTIVE] To compare neocollagenesis and elastin production stimulated by Radiesse® (calcium hydroxylapatite; CaHA, Merz Pharmaceuticals GmbH) and a hyaluronic acid-based filler (HA; Juvéderm® VOLUMA®).

[METHODS] Twenty-four women, aged 35-45, participated in this split-face, comparative study. Punch biopsies were taken 4 and 9 months after supraperiostal injection of each filler into the ipsilateral or contralateral postauricular area. Samples were analyzed for collagens type I and III, elastin, Ki-67, and inflammatory and angiogenic markers.

[RESULTS] At month 4, collagen type III was greater with CaHA vs HA (P=0.0052). By month 9, type I staining was higher with CaHA vs HA (P=0.0135), whereas type III was lower with CaHA than HA (P=0.0019). Staining for elastin, Ki-67 and angiogenesis was greatest with CaHA at both timepoints. Inflammatory markers increased most with HA treatment.

[CONCLUSIONS] CaHA resulted in more active, physiologic remodeling of the extracellular matrix than HA by stimulating a two-step process whereby collagen type I gradually replaced type III. Increased elastin stimulated by CaHA also indicates active remodeling. The results of this study suggest that, in the first 9 months after treatment, by reconstituting tissue homeostasis without inducing inflammation suggests CaHA has more desirable characteristics for a dermal filler than HA.