The nasolabial fold (NLF) is a natural wrinkle in the face, observed during smiling. The NLF is caused by the continuous movement of the lip elevator muscles and attachment of the muscle fiber to the skin.1 There is a difference in tissue density inside and outside the fold, with the fat layer on the upper part of the fold being relatively loose, while the inner layer is dense and tight.2 Methods to resolve the NLF include pyriform aperture implantation, midface lifting, and filler injection. The simplest method of filler injection is most commonly used. However, inside the NLF, there is a dense fascia with a thin superficial fatty layer, and due to the presence of a malar fat pad on the outer layer, the superficial fatty layer is thick. Injection is typically performed on the inner layer of the NLF, and the shape is not well maintained in the case of fillers.2,3 Moreover, bolus injection has the disadvantage of rapid spreading because the filler is in a gel form. Therefore, to address this disadvantage, the author introduces a multilayered injection technique.
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