Unilateral Brodie bite, called also Scissor bite, is a form of transversal malocclusion that often leads to minor facial asymmetry. The prevalence of this form of malocclusion is rare, especially met in mixed denture. We report a case of 11-year-old girl who presents unilateral scissor bite related to oral habits, with a skeletal class II. Modified activation by contraction of a bi-helix appliance was used to treat the unilateral scissor bite occlusion, before approaching the correction of the sagittal relationship.