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BACKGROUND: With a wide range of hyaluronic acid (HA) filler products available, knowledge of gel characteristics is a key part of tailoring treatments to each patient's aesthetic goals. This paper presents 2 main gel characteristics - strength/firmness and flexibility - for HA fillers produced using NASHA® and OBT™ and their clinical significance for tissue performance. METHODS: Three NASHA gels (Restylane®; Restylane Silk; Restylane Lyft) and 4 OBT gels (Restylane Refyne; Restylane Kysse; Restylane Volyme; Restylane Defyne) were studied in dynamic mode using a PP25 rheometric measuring system at 25 degrees C. Gel strength/firmness was measured using frequency sweep, with G prime evaluated at 0.1 Hz. Flexibility assessments used amplitude sweep measurements between 0.1% and 10,000% strain at 1 Hz, with xStrain being the strain value at the crossover point where G prime and G double prime have the same value. Results: Restylane, Restylane Silk, and Restylane Lyft had G primes of 701, 416, and 799 Pa, respectively. OBT G primes for Restylane Refyne, Restylane Kysse, Restylane Volyme, and Restylane Defyne were 70, 160, 171, and 271 Pa, respectively. The xStrain values were 1,442% (Restylane Refyne), 908% (Restylane Kysse), 930% (Restylane Volyme), 761% (Restylane Defyne), 7% (Restylane), 19% (Restylane Silk), and 17% (Restylane Lyft). Conclusions: OBT products had high flexibility (tolerance to deformation) and low to intermediate strength/firmness, which make them appropriate for dynamic facial areas. NASHA products showed greater strength/firmness, with the potential to create lift and projection. Altogether, NASHA and OBT HA gels covered a wide range of strength and flexibility. J Drugs Dermatol. 2024;23(1):1332-1336. doi:10.36849/JDD.7648.
Öhrlund et al. (Fri,) studied this question.