I got something like an ulcer at the front and back of my gum , beneath my dental bridge that i had for 2 years , don't know what it is, does not hurt?

See a dentist: You need to get an x ray and exam to rule out an abscess.

Ulcer: Likely an ulcer(s). Possible traumatic ulcer from rough crusty food or chips, etc. Possible herpes infection , though this would be painful. Possible aphthous ulcer, though this would also be painful. If it does not go away in 7-10 days or becomes painful, see your dentist to evaluate it. Meantime, warm salt water rinses may speed recovery. 1 tsp salt in 12 oz warm water. Good luck.

Have it checked: Please have it checked out, possibly with a biopsy. If the ulcer has changed size or color, please have it checked immediately.