Fig. 1

Potential problems with traditional methods of measuring maxillary incisor inclination. a The maxillary incisor long axis (line drawn from incisor tip through to the apex) and the labial face tangent, drawn as a tangent to the labial face of the maxillary central incisor in profile view. b The inclination of anatomical reference planes is subject to considerable individual variability, e.g. if the maxillary plane is inclined upwards at the back as shown in this diagram, and this would affect the measured incisor long axis inclination in relation to the maxillary plane, but not necessarily the inclination of the maxillary incisor labial face tangent. c There may be variation in the incisor crown-root angle, and, as such, the long axis of the incisor tooth may not match that of the crown. d There may be considerable variation between the inclination of the long axis of the maxillary central incisor and the inclination of a tangent to the labial face of the tooth crown; the latter is more important from an aesthetic point of view