Background: Injectable calcium hydroxylapatite is a soft-tissue augmentation material that is used off-label for facial augmentation, including repletion of depressed nasolabial folds. Objective: We sought to assess the safety of calcium hydroxylapatite injection for correction of nasolabial fold depressions. Specifically, we sought to obtain a quantitative assessment of injection-related adverse events using a reproducible placement technique with long-term follow-up. Methods: We conducted an open-label, single-center prospective study using reproducible technique with 1- to 1.5-year follow-up. All patients were treated with infraorbital nerve blocks. Then, parallel linear threading technique using 27-gauge/1.25-in needles was used to place 1 to 2 mL of injectant at the dermal subcutaneous junction into each pair of depressed folds. A triangular array of injectant was deposited under the melonasal junction. At follow-up at 2 to 3 weeks and at 1 to 1.5 years, respectively, patients were asked to report and characterize injection-related redness, swelling, bruising, nodule or granuloma formation, asymmetric correction, textural change, hypersensitivity reactions, degree of correction remaining, and overall satisfaction. In addition, patients who had received other injectable soft-tissue materials were asked to compare these with calcium hydroxylapatite in terms of risk profile and longevity of effect. Results: In all, 22 patients were treated and complete follow-up data were obtained from 18. Of the 18 patients, all reported at least mild postinjection redness and swelling, which abated within 1 to 5 days. Bruising was reported by fewer than half, and resolved within 4 to 10 days. Palpable but not visible nodules were reported by 2 of 18 patients; these resolved within 3 months of injection. Asymmetric correction, textural change, granulomas, and hypersensitivity reactions were not reported. In all, 14 of 18 patients reported that cosmetically significant correction lasted longer than 1 year. Two thirds of injected patients who had received other fillers for nasolabial fold correction preferred calcium hydroxylapatite, with the primary reason being increased longevity of effect. Limitations: There was a lack of objective outcomes measures. Conclusions: When a consistent, defined injection technique is used, injectable calcium hydroxylapatite appears to be a well-tolerated soft-tissue augmentation material for correction of nasolabial fold depressions. A long duration of effect may make this material particularly desirable for some patients.
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