1. Mouth: The mouth of an orangutan is more prominent than that of a human, with a shallow depression between the upper and lower lips and a wide mouth, which can hold more food.

2. Teeth: Orangutans have developed teeth, which are mainly used to chew hard plants and fruits. The front teeth are prominent and can be used for attack and self-defense. Canine teeth are also more developed, not as prominent as front teeth, and molars are wider, so they can chew plant fibers better.