A Randomized Clinical Trial Comparing Pure Hyaluronic Acid to the Hyaluronic Acid-Calcium Hydroxylapatite Combination for Temporal Volumization.

Background: Hyaluronic acid (HA) and calcium hydroxylapatite (CaHA) are commonly used for facial volumization, with HA offering hydration and reversibility, whereas CaHA provides structural support and collagen biostimulation. Recently, a combination of HA and CaHA has been proposed to enhance both immediate volumization and long-term tissue remodeling. However, its efficacy for volume retention remains unclear.

Objectives: In this study, the authors aim to compare the volumetric retention and clinical outcomes of HA alone vs a manually prepared HA-CaHA mixture in the temporal region over a 90-day follow-up.

Methods: A randomized controlled trial included 20 patients (40 hemifaces) treated with either 0.5 mL of HA alone (G1) or a 40% HA and 60% CaHA mixture (G2). Fillers were injected subcutaneously using a 22 G cannula with a fan technique. Volumetric changes were assessed through 3-dimensional stereophotogrammetry, and the Allergan Temple Scale (ATS) evaluated qualitative outcomes.

Results: Both groups showed significant ATS score improvements over time ( < .001), but volumetric analysis demonstrated greater retention in G1 (0.231 ± 0.255 mL) compared with G2 (0.028 ± 0.135 mL, = .016).

Conclusions: The hypothesized synergy of the HA-CaHA combination was not observed. HA alone provided superior long-term volumization, suggesting that manual HA-CaHA mixing may alter filler performance. Further studies should explore premixed formulations and optimize treatment protocols.