Could you bruise adult teeth?

Accident. You can cause a bruise like situation in the gum tissue that supports the tooth if you bite down hard on something and you're not expecting it in the food. You can also get the same reaction from trauma to the teeth, such as running into a door, hitting your teeth on steering wheel in an accident, etc.
Tooth trauma. Like any living body part, teeth can be bruised. A blow to the face whether it be a from a foreign object or punch/kick can bruise a tooth. A tooth can be knocked loose or even knocked out. When a tooth is bruised it can turn a different color- it may simply get darker or become brownish-orange. Best advice would be to see your dentist if this has happened to you.