Effectiveness and Safety of a Polyvinyl Alcohol Microsphere and Hyaluronic Acid Suspension for Chin Augmentation: A Randomized Controlled Trial and Multidisciplinary Study

Abstract Background Dermal fillers are a primary treatment for chin retrusion. However, current options have limitations in longevity and biomechanical properties. Objectives To evaluate the efficacy and safety of a novel filler, comprised of polyvinyl alcohol (PVA) microspheres suspended in hyaluronic acid (PVA-HA), for chin augmentation.. Methods The physicochemical properties of PVA were were compared to traditional filler materials using contact angle, Young's modulus, friction-wear, and scanning electron microscopy tests. Biocompatibility was assessed in animal models via histopathological and immunofluorescence analyses. Subsequently, a prospective, randomized controlled trial was conducted from June 2021 to March 2023 in 144 subjects with chin retrusion, randomized 3:1 to receive PVA-HA or no treatment. Efficacy was assessed by changes in the Glabella-Subnasale-Pogonion (G-sn-Pog') angle, a chin retrusion scale and Global Aesthetic Improvement Scale (GAIS). Results Preclinical tests demonstrated that PVA microspheres had favorable hydrophilicity, softness, and mechanical properties comparable to natural periosteum. In animal models, PVA-HA exhibited excellent biocompatibility with only a mild, transient inflammatory response. In the clinical trial, the PVA-HA group showed a mean G-sn-Pog' angle increase of 1.12° (95% Confidence Interval [CI]: 0.83°, 1.41°) at 60 weeks, compared to a mean decrease of 0.42° (95% CI: -0.87°, 0.03°) in the control group (between-group difference, 1.54°; p<0.01). Significant improvements were also observed on GAIS and chin retrusion scale (both p<0.001). Adverse events were primarily mild-to-moderate, transient injection site responses. Conclusions The novel PVA-HA filler demonstrates favorable physicochemical and biocompatibility properties. It provides clinically significant and safe outcomes in chin augmentation, representing a promising new option for soft tissue filling.