If anyone is having their game crash upon loading, I suggest deleting esp files such as: 'FCO - Russel.esp' which came with FCO, despite me not choosing it during the installation process. I guess the mod author made a separate esp file for configuration reasons.
When I put this file back into the steam\steamapps\common\fallout new vegas\data folder, the mouth textures returned.
I had this problem, but I realized that I had accidentally deleted the file: 'FCO - OHSB NPC Edits.esp'
