Characterizing Major In Vitro Rheologic and Physicochemical Properties of Thermally Altered Hyaluronic Acid Fillers

BACKGROUND: Optimizing aesthetic results for soft tissue augmentation and skin resurfacing often requires multiple treatment modalities. How energy-based device (EBD) treatments alter properties of previously injected hyaluronic acid (HA) fillers is unknown. OBJECTIVE: To evaluate whether elevated temperatures during EBD treatments alters key properties of HA fillers. MATERIALS AND METHODS: Four HA fillers (Belotero Balance, Juvéderm Volbella, Juvéderm Ultra XC, and Restylane Eyelight) were heated to 65 or 100°C to simulate temperatures of nonablative lasers or ablative lasers, respectively, or kept at room temperature. The authors assessed storage modulus (G'), loss modulus (G″), cohesivity, and water absorption. RESULTS: No significant changes were observed in G' and G″, except for increases in G' for Juvéderm Ultra XC at 100°C (16.67 Pa, Δ = +11%) and Juvéderm Volbella at 100°C (92.67 Pa, Δ = +49%). Cohesivity was stable with only minor increases (<0.8 points on a 1-5 scale) for Juvéderm Ultra XC and Belotero Balance at 65°C. Water absorption remained consistent across all HA fillers and temperature conditions. CONCLUSION: Overall, in vitro heat exposure of tested HA fillers does not alter rheologic and physicochemical properties. These findings suggest that EBDs over preinjected HA fillers are unlikely to compromise filler integrity. Further in vivo validation is necessary.