What do you do if you have a cavity under your bridge?

If you get a cavity under an existing bridge you will need to have the entire bridge replaced with a new one or have a dental implant placed.  If you choose a dental implant for the missing tooth you will need two new crowns for the teeth that supported your old bridge.   Good luck.  

Usually bridges need to be replaced at least every 10 years, there are some exceptions, but imagine something working 3 times a day 365 ,with stress, so there is always a chance of needing an adjustment, also receding gums, can cause a cavity on the root of the tooth, seeing there is a cavity it's time to change it, you should think about getting a dental vacation, relaxing and changing that bridge,for a new one.