The Root of Premolar Tooth to Infra-Orbital Canal: From the root of the first premolar tooth to the mid level of the infra-orbital canal.
Infra-Orbital Canal to Root of Canine Tooth: Measurement is taken vertically from the mid-level of the in infra-orbital canal to the root of the canine tooth.
Mandibular Length: From the level of the cranial extremity of the alveolar root of the incisor to the level of the caudal border of the mandible.
Lateral Alveolar Root to Mental Foramen: Shortest distance from the mental foramen to the lateral extent of the alveolar root of lower incisor.