Evaluation of the Hydrophilic, Cohesive, and Physical Properties of Eight Hyaluronic Acid Fillers: Clinical Implications of Gel Differentiation

Kaitlyn M Enright,1 Steven F Weiner,2 Kalpna K Durairaj,3 Mirko S Gilardino,4 Andreas Nikolis5 1Clinical Research Unit, Erevna Innovations Inc, Westmount, Quebec, Canada; 2The Aesthetic Clinique, New York, NY, USA; 3Beauty by Dr. Kay, Pasadena, CA, USA; 4Division of Plastic Surgery, McGill University, Montreal, Quebec, Canada; 5Clinical Research Unit, Erevna Innovations Inc, Westmount, Quebec, Canada; Department of Plastic Surgery, McGill University, Montreal, Quebec, CanadaCorrespondence: Kaitlyn M Enright, Clinical Research Unit, Erevna Innovations Inc, 376 Victoria Ave., Suite 400A, Westmount, QC, H3Z 1C3, Canada, Tel +1 514-488-0163 Ext 256, Email research@vicpark.comBackground: Hyaluronic acid (HA) fillers are used to treat an array of aesthetic indications. Proper filler selection is paramount for successful patient outcomes. However, many important physiochemical and physical properties that impact HA gel behavior remain undefined.Purpose: To evaluate the hydrophilicity, cohesivity and particle size of eight commercial HA fillers manufactured by either Non-Animal Stabilized Hyaluronic Acid (NASHA) or Optimal Balance Technology (OBT) techniques.Methods and Materials: Three individual in vitro experiments were performed to assess HA swelling capacity, cohesion, and particle size. Image analyses, blinded evaluation using the Gavard-Sundaram Cohesivity Scale, and laser diffraction technology were utilized, respectively.Results: Compared to fillers manufactured with NASHA technology, OBT products demonstrated greater swelling capacity, cohesion, and wider particle size distributions. Strong positive correlations between swelling factor, degree of cohesivity, and increasing widths of the particle size distributions were observed.Conclusions: The hydrophilicity, cohesivity and particle size distributions vary among HA fillers manufactured with different techniques. The creation of new labels identifying products based on their unique combination of physiochemical an