Fig. 3

The flat under-surface of the horizontal part of the measuring instrument is placed on the higher maxillary canine orthodontic bracket hook (though it may be placed on a unilateral segment of any bilateral structure), and held perpendicular to the true vertical. For patients with a relatively symmetrical upper face, and no vertical orbital dystopia, the horizontal part of the measuring instrument may be held approximately parallel to the interpupillary plane (a dental mirror handle may be held in line with the interpupillary plane, to aid visualisation at the chair side). The vertical ruler is held next to the contralateral canine tooth, and the vertical distance measured directly from the canine bracket to the flat under-surface of the horizontal part of the measuring instrument. This vertical distance quantifies the overall extent of movement required to level the maxillary occlusal plane