Hyaluronan Dermal Fillers: Efforts Towards a Wider Biophysical Characterization and the Correlation of the Biophysical Parameters to the Clinical Outcome.

The gels proved highly cohesive and sensitive to ROS action with stability declining with the decrease in the overall gel elasticity. The G* and complex viscosity values at clinically relevant frequencies and gel water-uptake ability are consistent with the relative clinical indication related to gel projection and hydration capacity. Clinical outcomes showed the safety of the products and a perception of palpability well correlating with the cohesive/viscosity properties of the gels. A similar duration of the aesthetic effect (up to 1 year) was observed despite the diverse in vitro gel stability. The results broaden our knowledge of these gels and may contribute to optimize their clinical use towards the improvement of patient safety and satisfaction. Initial clinical observation indicated that gel biophysical properties allow for a reliable prediction of gel palpability, while in vitro data on gel stability cannot be related to the duration of the observed skin improvement. The latter finding further corroborates the idea of a skin restoration process activated by the gels besides the physical volumetric action.