Prospective Intraindividual Split-face Histological Comparison of Poly-d,l-lactic Acid and Calcium Hydroxylapatite Skin Boosters Using Stem Cell Markers

Background

Poly- d,l -lactic acid (PDLLA) and calcium hydroxylapatite (CaHA) are injectable biostimulators increasingly used as skin boosters. Although both promote tissue regeneration, their comparative histological effects in humans remain poorly characterized, particularly regarding differential vascular, collagenous, and elastinrelated responses that may influence individualized treatment strategies and clinical decision-making.