There are certain aspects of the smile that is significant for the orthodontist’s treatment diagnosis and planning that is revealed only through the oblique view. The most desirable positioning is that the maxillary occlusal plane is compatible with with the curvature of the lower lip on smile. Deviance from this orientation includes an upward cant of the anterior maxilla, a downward cant of the posterior maxilla, or variations in both. Thus it is important to visualize the relationship of occlusal plane to the lower lip during initial patient examination and diagnosis and treatment planning. Whether the posterior maxilla should be impacted or the anterior maxilla should come down depends on the amount of incisor show at rest and on smile and the smile arc relationship.
The degree at which the incisors are inclined forward can also have a significant effect on incisor display. Flaring maxillary incisors result in diminished incisor show from the front view. On the other hand, upright maxillary incisors cause increased incisor display.