Introduction: Few studies have evaluated the durability of tissue filler products in an objective and non-invasive manner. The aim of this study was to evaluate the durability of a formulation of hyaluronic acid (Derma Hyal®) for filling nasolabial folds by comparing perceptions of clinical effect and soft tissue thickness as measured by ultrasound. Methods: Ten women were treated. Clinical and ultrasound evaluation were performed after 1, 3, 6, 9, and 12 months. Results: The average thickness of the nasolabial folds as measured by ultrasound was 0.38 ± 0.14 mm at pretreatment, 0.69 ± 0.19 mm after 1 month, 0.65 ± 0.17 mm after 3 months, 0.61 ± 0.22 mm after 6 months, 0.57 ± 0.23 mm after 9 months, and 0.55 ± 0.14 mm after 12 months. Data analyzed using Friedman's test were not statistically significant. Regarding satisfaction, at 6 months, 3 patients considered the result unsatisfactory; 5, barely satisfactory; and 2, satisfactory. Only 1 patient considered the result satisfactory at 9 months. After 12 months, 1 patient considered the result barely satisfactory and the other patients, unsatisfactory. All patients stated that they would undergo the procedure again. Conclusions: Ultrasound proved to be an objective and non-invasive method of evaluating filling durability, provided that it is correlated with clinical parameters. An increase in skin thickness was demonstrated up to 12 months after injection of the product into the nasolabial fold, followed by a progressive decrease after this period. Although differences among the values as measured by ultrasound were observed over time, these were not statistically significant. Patients perceived a clinical effect up to 9 months after the product was applied.
Keywords: Hyaluronic acid. Ultrasonography. Face.