Fig. 1
From: Clinical research: low-level laser therapy in accelerating orthodontic tooth movement
The left-hand coordinate system applied to image reconstructions of the mouth for measuring retraction distances. O, incisive papilla; A, median end of the right third palatal rugae; B, median end of the left third palatal rugae; P, midpoint of the orthodontic bracket on the occlusal edge. The XY plane was established based on points O, A, and B. Point O was regarded as the coordinate origin, and the X-axis points away from the origin in the O-A direction. The Y-axis is perpendicular to the X-axis through the origin, and the right side of the upper dental arch was in positive direction