Abstract
BACKGROUND: There are several published articles on characterization of fillers, describing methods for both chemical and physicochemical characterization. Recently a lot of focus has been on the development of methods for measuring cohesion of hyaluronic acid (HA) fillers. OBJECTIVE: The aim of this study is to investigate and compare the drop-weight method and the correlation between cohesion and other physicochemical properties using a variety of HA fillers. MATERIALS AND METHODS: HA fillers covering several product families and manufacturing techniques were used. The HA fillers also covered a range of HA concentrations from 12 to 24 mg/mL. Cohesion was determined using sensory evaluation and the drop-weight method. Other physicochemical properties evaluated were rheology and the swelling factor. RESULTS: In this study, it was verified that values obtained by the drop-weight method reflect the perceived cohesion very well. The correlation with rheology is affected by the HA concentration in the products. A remarkably good correlation between swelling factor and cohesion was found. CONCLUSION: Cohesion correlates with other physicochemical methods. It could be discussed whether there is a need for a separate cohesion method because other already established physicochemical methods such as rheology and swelling factor can describe the underlying properties that affect cohesion.