Changes in Volume of Lips in 3-Dimensional Analysis and Projection of Lips in Sonography After Injection of Particle-Type Hyaluronic Acid Filler Utilizing a 9-Point Injection Technique.

[BACKGROUND] Lip augmentation procedure with hyaluronic acid (HA) fillers can make patients younger with more attractive. After the injection on the lips, the result is temporary. Physicians and patients wonder how long the HA filler last on the lips.

[OBJECTIVES] The main goal of this study is to determine how much volume of HA is reduced after injection on the lips utilizing a "9-point" injection technique.

[METHODS] In this prospective study, 25 females were injected using HA filler and evaluated using noninvasive 3-dimensional-scanner analysis before, 1 h, 1 week, 1 month, 6 months, and 9 months after injection. The changes in projection of lips were evaluated using sonography. The patients were treated as usual manner in a single clinic. Using 29-gauge needle, 20 mg/mL of HA filler was injected into the lips. Default injection amount was 1 cc. HA filler was injected submucosally using linear thread and fanning technique.

[RESULTS] Twenty-three patients were followed up. The mean age was 34.8 years (range, 20-48 years). The volume of lips became 181.34% (±61.14) at 1 h, 91.18% (±10.12) at 1 week, 75.09% (±11.02) at 1 month, 55.36% (±10.48) at 6 months, and 39.21% (±4.54) at 9 months. The projection of upper lip areas increased 25.3% at 1 h, 22.8% at 1 week, 17.7% at 1 month, 14.8% at 6 months, 11.5% at 9 months in sonography. The projection of lower lip areas increased 23.1% at 1 h, 20.7% at 1 week, 15.9% at 1 month, 13.9% at 6 months, and 10.6% at 9 months in sonography.

[CONCLUSIONS] Lip augmentation with HA showed improved shape during 9 months. The volume of HA decreased at a constant rate after injection, except for the first week. Injected HA was absorbed at a constant rate, and more than half was absorbed after 9 months utilizing a "9-point" injection technique.