Contemporary Ortho Appliances Practice Test

Wits appraisal is a way to quantify anteroposterior skeletal disharmony by looking at how the jaws relate to each other on the occlusal plane. It does this by projecting the A point and the B point onto the occlusal plane to create A′ and B′, and then measuring the distance between these projections along that plane. That linear distance reflects sagittal jaw relationship independent of cranial base angles or incisor tilt, which is why it’s a useful supplement to angular measures.

In interpretation, a positive distance points to a Class II pattern (the maxilla ahead of the mandible), a negative distance points to a Class III pattern (the mandible ahead), and a distance near zero indicates Class I. Because it uses the occlusal plane, Wits correlates with what SNA and SNB imply about maxillary and mandibular positions relative to the cranial base, but it gives a direct occlusal-plane measurement of the AP discrepancy. This makes it particularly helpful for planning treatment, including decisions about growth modification or orthognathic surgery, as it emphasizes the functional jaw relationship you’ll actually see when the teeth fit together. It does not assess vertical discrepancies, root proximity, or nasal airway resistance.