Background: To minimize complications with injectable fillers, aesthetic practitioners need a detailed knowledge of facial anatomy.

Objective: To describe a novel approach ("subtractive anatomy") to identify locations where lip eversion using filler injections would be well tolerated and to evaluate the "French kiss technique" (FKT) to enhance the length of the lips using a low cohesivity hyaluronic acid filler.

Materials and methods: Twenty hemifaces were dissected from 10 nonembalmed, nonfrozen Caucasian cadavers to assess subtractive anatomy. The FKT "proof-of-concept" evaluation enrolled 120 patients (114 women; mean age 42 years).

Results: The arterial supply of the lips shows marked anatomical variations between patients and when comparing sides of the face in the same person. The dissections revealed a "safe area" for filler injections in the submucosal plane 3 to 4 mm above the vermilion-mucosa junction of the upper lip and 3 to 5 mm below the vermilion-mucosa junction of the lower lip. Preliminary results suggest that FKT is associated with very good cosmetic outcomes and no major complications.

Conclusion: Based on our anatomical studies and the literature, we developed the novel FKT for the injection of lip fillers, which produced a marked natural lip plumping effect. Further evaluation is underway.