Table 1.

Landmarks, variable definitions, and localizations

Abbreviation	Description	Localization
PR	Posterior right	Landmark at bone relative to the root apex of upper right second molar
PL	Posterior left	Landmark at bone relative to the root apex of upper left second molar
AR	Anterior right	Landmark at bone relative to the root apex of upper right central incisor
AL	Anterior left	Landmark at bone relative to the root apex of upper left central incisor
CR	Canine right	Landmark at bone relative to the root apex of upper right canine
CL	Canine left	Landmark at bone relative to the root apex of upper left canine
PR-PL	Posterior right to posterior left	Distance of the posterior right to posterior left landmarks
CR-CL	Canine right to canine left	Distance of the canine right to canine left landmarks