How do u tramatize a tissue in your mouth? Or any tissue?

Direct trauma. Usually traumatized tissue is a result of direct or excessive contact with something in the mouth like toothbrush used too vigorously etc. Anytime one uses excessive or repetitive force in mouth or elsewhere then trauma of tissue is possible.
Number of ways. Anything thing that put too much force on a tissue will injure it, cause traums. Theer are a number of ways to traumatize your mouth tisses. Biting yourself while eating or grinding your teeth, brushing with excessive forces, jabbing yourself with your toothbrush or hard foods bruning, drinking hot liquids, getting hit in the mouth or face, the list goes on and on.