Stresses occurring in the PDL in occluso-apical direction (sz normal stresses) during closing stroke. A load of 350N was applied along the tooth’s longitudinal axis. Diagram shows FE results for the three different age groups (A-C) on both the shifting side (1) and side where shifting side is averted (2). Tensile stresses are demonstrated by positive scale values (yellow to red), compressive stresses by negative scale values (green to blue). Dimension of stresses increases with increasing tooth age (please note the different age-related scales).