• the “Holdaway Ratio” is used to evaluate the prominence of the mandibular incisors and bony chin. The ratio is calculated by comparing the distance of the lower incisor edge and pogonion to the N-B line. Ideally, the Holdaway Ratio should be approximately 1.0 in males and 0.5 to 1.0 in females. This relationship is useful in planning for genioplasty.