Reply: Unexpected Bone Resorption in Mentum Induced by the Soft-Tissue Filler Hyaluronic Acid: A Preliminary Retrospective Cohort Study of Asian Patients.

Abstract

Background As one of the most commonly used soft-tissue fillers, hyaluronic acid is generally considered safe and efficacious. However, evident bone resorption in mentum was observed. In this study, the authors analyzed the impact of hyaluronic acid on bone resorption in mentum and the influencing factors. Methods The authors retrospectively compared the computed tomographic scans of patients with or without mentum augmentation using hyaluronic acid. The body mass index- and sex-matched control group was selected randomly. Semimandibular bone resorption index was calculated as the ratio of bone thickness in the incisive fossa to that in the mandibular symphysis. Injection volume, injection interval, the number of injections, product, complication were also recorded. Results From January of 2014 to June of 2019, 80 patients (160 cases) and 80 controls were recruited. The bone resorption index in the hyaluronic acid injection cohort was significantly lower than in the controls (75.25 ± 10.02 versus 82.86 ± 6.38; p = 0.000). Patients injected with greater than or equal to 1 ml per time were more susceptible to bone erosion compared with patients injected with less (68.89 ± 10.84 versus 76.49 ± 9.42; p = 0.000). There was no significant difference between one- versus multiple-injection groups and short-injection-interval versus long-injection-interval (≥6 months) groups. Furthermore, no reduced aesthetics were realized. Conclusions Hyaluronic acid injection could induce bone resorption in the mentum; nevertheless, the aesthetics were not impaired. The severity of the bone loss was positively correlated with the injection volume per time; therefore, large-volume injection of hyaluronic acid should be performed with caution. The patients should be fully informed about this complication preoperatively. Clinical question/level of evidence Therapeutic, III.