After you have applied some animation and perhaps sculpted the mouth area, you can do some fine-tuning of the mouth corners, set teeth collision buffers, lip curl, and change the interior mouth depth.
Teeth Collision values create a buffer that prevents the teeth from going through the mouth geometry, especially noticeable with certain extreme mouth poses. This way, lips can properly compress against the teeth and wrap over and under them. Lower values decrease the teeth buffer for a closer fit of the lips over the teeth, while higher values increase the buffer.
The outer lip has control points that do collision checking with the teeth. The Upper/Lower A, B, C, and D sliders allow you to bend the outer lip. These values are collision checking factors that shrink or expand the effect of the teeth against the lips.
The Upper/Lower A slider manipulates the control point at the outer edge of the mouth, Upper/Lower D controls the control point closest to the lip curve, and Upper/Lower B and C manipulate the control points between A and D.
You can also adjust the teeth collision against both corners of the mouth using the RCorner and LCorner sliders.
Angle and Stretch parameters let you adjust the angle of the mouth corners and the amount that each inner corner of the mouth stretches. You can adjust these values for each of the four mouth corners (upper and lower left and right), or just the upper and lower lip in general.
Lip Curl Out and Lip Curl In values determine how the lips curl over the teeth. You can set the lip curl for each of the four mouth corners (upper and lower left and right) or just the upper and lower lips in general.
For Lip Curl Out, higher values push the lips away from the teeth, while lower values make the lips curl in over the teeth. On outer curl, the back points of the lips are held back.
For Lip Curl In, higher values make the lips curl in over the teeth, while lower values push the lips away from the teeth.
