The mouth, or oral cavity, is the first part of the digestive tract. It is adapted to receive food by ingestion, break it into small particles by mastication, and mix it with saliva. The lips (lingual), cheeks (buccal, and palate form the boundaries. The oral cavity contains the teeth and tongue and receives the secretions from the salivary glands.
A complete set of deciduous (primary) teeth contains 20 teeth. There are 32 teeth in a complete permanent (secondary) set. The shape of each tooth type corresponds to the way it handles food.
Source: National Institutes of Health
August 8, 2013