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

[BACKGROUND] Dermal fillers are a primary treatment for chin retrusion. However, current options have limitations in longevity and biomechanical properties.

[OBJECTIVES] The aim of this study was 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 compared to those of traditional filler materials by measuring the contact angle, Young's modulus, and friction wear, and by scanning electron microscopy analysis. 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, randomly allocated 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 the Global Aesthetic Improvement Scale.

[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% CI, 0.83°-1.41°) at 60 weeks, compared with a mean decrease of 0.42° (95% CI, -0.87° to 0.03°) in the control group (between-group difference, 1.54°; P < .01). Significant improvements were also observed on both the Global Aesthetic Improvement Scale and the chin retrusion scale (both P < .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.