Clinical Study for Accurate Injection Site of Botulinum Toxin A in the Correction of Gummy Smil

Kim, Young Jin; Jun, Young Joon; Bae, Joon Sung

Abstract

Gummy smile refers to the excessive exposure of the upper gum when a one smiles, more than 2-3 mm, accompanying the elevation of upper lip. Recently, it is of an increasing concern that the injection of botulinum toxin A to levator labii superioris alaeque nasi muscle and levator labii superioris muscle which are major lip-elevating muscles, has the corrective effect by weakening of these muscles. It is important to understand anatomical marker of the targeted muscle to which safe and effective injection can be performed. This study was performed to investigate the marker to find the targeted muscle easily applicable in practice by reviewing previous literatures. From January 2004 to May 2005, on 5 females that have a gummy smile, we marked injection points to the target muscle, and confirmed their effectivity, accuracy, and safety by EMG. Then we injected botulinum toxin A, and investigate amount of the gum exposure when smiles and occurrence of the side effect serially. 4 weeks after injection, we observed satisfied result without any side effects. Conclusively, as injection points of botulinum toxin A which we presented, are comparatively correct by anatomy, they are easily applicable in practice.