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

Area of Science:

• Aesthetic medicine
• Dermatology
• Biomaterials science

Background:

• Optimizing aesthetic outcomes often involves combining soft tissue augmentation with skin resurfacing.
• The impact of energy-based devices (EBDs) on pre-existing hyaluronic acid (HA) fillers is not well understood.

Purpose of the Study:

• To investigate the effects of elevated temperatures, simulating EBD treatments, on the properties of HA fillers.
• To determine if heat exposure alters key rheologic and physicochemical characteristics of HA fillers.

Main Methods:

• Four HA fillers were subjected to temperatures simulating nonablative (65°C) and ablative (100°C) lasers, or room temperature.
• Evaluated parameters included storage modulus (G'), loss modulus (G″), cohesivity, and water absorption.

Main Results:

• No significant changes in G' and G″ were observed, except for minor increases in specific fillers at 100°C.
• Cohesivity remained largely stable, with minimal changes observed at 65°C.
• Water absorption was consistent across all tested HA fillers and temperature conditions.

Conclusions:

• In vitro heat exposure does not substantially alter the rheologic and physicochemical properties of the tested HA fillers.
• EBDs used over pre-injected HA fillers are unlikely to compromise filler integrity based on these findings.
• Further in vivo studies are recommended to validate these in vitro results.