Rheological and Structural Analysis of Hyaluronic Acid Fillers Used for Chin Augmentation

Introduction: Chin contouring and projection represent some of the most frequently requested procedures in aesthetic practice using hyaluronic acid (HA) fillers. Variations in the physicochemical and viscoelastic properties of HA fillers may directly influence clinical performance. This study aimed to compare four commercially available HA gels specifically indicated for chin projection: JUVÉDERM^® VOLUX, RESTYLANE^® LYFT, PERFECTHA^® SUBSKIN, and RESTYLANE^® SHAYPE. Methods: The samples were characterized using scanning electron microscopy, dynamic light scattering, zeta potential, and swelling factor (SF). Rheological assessments included frequency sweep, amplitude sweep, and cohesivity modulus (MOC). All tests were performed in triplicate. Results: JUVÉDERM^® VOLUX exhibited the highest SF values (3.28–3.37), indicating greater swelling capacity, whereas RESTYLANE^® LYFT showed the lowest (1.53–1.66), reflecting a denser and less expansive profile. Rheological analysis revealed that RESTYLANE^® LYFT and RESTYLANE^® SHAYPE had higher storage modulus (G′) values at elevated frequencies. MOC was significantly higher for RESTYLANE^® SHAYPE and PERFECTHA^® SUBSKIN compared with JUVÉDERM^® VOLUX, suggesting greater resistance to deformation. Conclusions: Overall, RESTYLANE^® SHAYPE demonstrated the most favorable balance, combining moderate SF, high G′ values, and elevated MOC. However, patient-specific anatomy, aesthetic goals, and injector expertise remain critical in determining the most appropriate product for chin contouring.