Horizontal animation deformity as unusual complication of neurotoxin modulation of the gummy smile.

ABSTRACT

Injections of botulinum toxin type A represent the most common nonsurgical cosmetic treatment worldwide. The authors report a case of dynamic horizontal wrinkling in the upper lip that appeared after botulinum toxin type A injections to treat gummy smile associated with nasal alar base reduction, in a 28-year-old woman. The anatomic features and pathogenic mechanism underlying this unusual complication are analyzed and discussed.