The Interdimensional Traveler: A Full Body Character Design - ZBrush Creature Design: Creating Dynamic Concept Imagery for Film and Games - page 139

Using Topological Masking
Now we want to open the lips slightly to expose the teeth. We will use the Move Topological brush to ac-
complish this task ( Figure 3-38 ) . You may notice that if you try to move the lips with the normal Move brush
it will grab all of the faces under the red brush falloff circle, making it impossible to separate the two lips.
The solution to this is to use a special variant on the Move brush called Move Topological. Move Topolo-
gical will move the underlying faces with a falloff based on how close the faces are topologically instead of
just moving all of the faces under the brush falloff. The model in Figure 3-39 is colored to show how the
falloff of the Move brush compares with the falloff of the Move Topological brush. Follow these steps to
use the Move Topological brush.
Figure 3-38: Open the lips slightly with the Move Topological brush to reveal the teeth.