07 November 2025 : Review article
Facial Injectable Fillers in Aesthetic Medicine: Clinical Applications and Safety Strategies
Jie Liu A 1, Ming Gao EF 2, Huilin Hu CF 2, Hanyu Pang
BD 2, Yuyang Liu EF 2, Peng Zhang A 1*
DOI: 10.12659/MSM.949944
Med Sci Monit 2025; 31:e949944
Table 3 Properties of hyaluronic acid (HA) dermal fillers and effect on product performance.
| Properties | Definition | Effect in product performance | Practical aspects |
|---|---|---|---|
| Concentration | Total HA in the hydrogel | Hydrogel hardness and duration at the application site | The standard concentrations of HA in commercial products commonly used are 20 and 24 mg/mL, particularly in facial fillers, which are regarded as the industry benchmark. For the treatment of fine or superficial lines, hydrogels containing HA concentrations equivalent to or below 20 mg/mL have been traditionally used |
| Swelling factor | Capacity to retain water in hydrogel structure and expand. | Expansion capacity; volumizing effect | High-expansion-capacity hydrogels are more suitable for addressing deep folds and facial regions that exhibit high degrees of mobility, such as nasolabial folds |
| Degree of crosslinking | Percentage of HA monomers linked to a crosslinker molecule. | Hydrogel hardness and ability to resist enzymatic degradation | High crosslinking density results in a longer residence time of the product on the skin. BDDE, DVS, and PEGDE are the most used crosslinking agents in the production of HA for facial fillers. This extended residence time ensures a more effective and longer-lasting filling effect, making these crosslinking agents essential for creating high-quality facial fillers |
| Particle size | Size of crosslinked HA fragments | Indication of the most appropriate application site | Dermal fillers presenting larger particles are more indicated to deeper wrinkles |
| Viscoelasticity | Elastic and viscous behavior | Rheological behavior of the hydrogel after application | High elasticity ensures a volumizing effect, and it is imperative that the facial filler possesses sufficient viscosity to facilitate ease of injection |
| G’ | Elastic properties and hardness | Ability to return to its original shape. The increased residence time of facial fillers in the application site | High G’ value dermal fillers exhibit increased rigidity and deformation resistance, making them suitable for addressing deeper wrinkles. Conversely, dermal fillers with lower G’ values are utilized in the treatment of superficial wrinkles |
| G’ | Viscous properties | Ability to flush the hydrogel through the needle | Higher G’ hydrogels possess greater thickness, necessitating increased force during injection. To enhance injectability, the incorporation of uncrosslinked HA may be contemplated |
| Cohesivity | Capacity of adhesion between crosslinked HA molecules | Hydrogel integrity and its distribution profile into the skin after application | Formulations demonstrating low cohesivity are more recommended for the treatment of facial regions with greater mobility, as they are easier to mold. Conversely, formulations with high cohesion are preferred for application in deeper skin regions and areas with more restricted movements |