As with so many other disciplines, there's a certain amount of trial and error that goes into 3D modeling. The method I used over the last two days to get that interior mouth view through Creed's right cheek was not working.
First, deleting polygons in Maya to create the hole actually made all my sculpting layers for Creed go away. The sculpting layers allow me to do things like switch his feet from regular to boot position, or to remove the sculpted in wounds. Layers allow for much greater flexibility if I want to change anything, in other words.
I didn't realize the layers had gone away though until I had done a bunch of work trying to sculpt the existing inner-mouth geometry. That wasn't working as well as I wanted it to either, but when I saw that my layers were gone, I had to think of a new solution.
So, this is what I've done today.
1. In zBrush, masked off the cheek wound where I want the hole to be, then reversed the mask so that any changes will only affect the cheek.
2. Pulled that cheek area a bit into the face, and then enlarge the cheek area. This causes the skin at the edges of the wound go fold in, giving the skin a look of thickness.
3. Send the main Creed mesh and the gums/teeth over to Maya from zBrush, for reference. Modeled the interior of the mouth as a new object. The mouth interior includes gums, tongue, and uvula.
4. Send the interior of the mouth back over to Maya for sculpting.
5. Deleted the old gums.
Now, here are a couple of future steps that will make this all work.
1. The black area on the cheek will be used to create a transparency map in Maya. In other words, it will be invisible.
2. Make most of the mouth/throat tube on the main Creed mesh transparent. That way only the new interior will be seen.
The funny thing is, now that I figured out this better method, the work is going really fast!