Swelling can occur in your mouth for a variety of reasons. These can include:
Infection is the most common source of dental inflammation and swelling, and most frequently occurs in a cracked tooth or a tooth with deep decay. There are also non-infectious sources of swelling that can affect your jaws, or block salivary glands. Depending on the location of the infection or inflammation, you may notice swelling in your cheeks, gums (gingiva), the floor of the mouth, lips, or neck.
Swelling in the mouth may or may not be an emergency that requires a trip to an emergency department or urgent care facility.