Ambient occlusion is a "fake" global illumination technique, its faster and it looks similar, however it is a very crude approximation to full global illumination

occlusion is calculated by shooting a number of rays in the reflection direction.

thrombotic occlusion

Gunnar Svanberg has written:

'Experimental trauma from occlusion in the dog' -- subject(s): Occlusion (Dentistry), Dental Occlusion

it is said to be in normal occlusion when the teeth are present and occluding in a healthy, stable, and pleasant manner while ideal occlusion or we all know "perfect occlusion" is the relationship existing when all the teeth are perfectly placed in the arches of the jaws and have a normal anatomic relationship to each other. We can attain normal occlusion but never an ideal occlusion.

-irishkim7