<s>[INST] I have a five year old four prong bridge, which was not installed correctly, therefore a large piece of my gum was left around the side of my tooth where food collected which seems to have caused decay. When I bite on the tooth if feels as though it is moving up and down and it is very tender. I am being told that I need to have a root canal and have the bridge made over. My problem is I don t have six-thousand dollars. Should my dentist be able to take off my existing bridge to perform the root canal and then put my old bridge back in place? Or is their a much more inexpensive to correct this problem. My dentist states that there is a space around the wisdom took which is allowing food and will, if it has not yet, cause decay. [/INST] Hello & welcome, Improper placement or making of the bridge, creates the problem which you are facing & that is food collection. Food accumulation around tooth or under the bridge causes decaying or caries in the abutment tooth (support tooth). And if you are getting the feeling of tooth going slightly down on application of pressure, then that particular tooth has been decayed to pulp level & there is abscess formation around the tooth. Abscess present around the tooth gives cushioning effect on application of pressure along with pain & swelling. If this is the case, it can definitely be treated with Root canal treatment followed by placement of new bridge with proper crown preparation by dentist.  Definitely the role of antibiotics & painkillers is vital here as there is infection along with abscess formation. Yes you should go for making new bridge because doing root canal treatment only will not clear the main problem associated with the bridge (gap underneath). This can only be treated with repeated crown cutting & impression taken with due care by the dentist.  If there is food accumulation around wisdom tooth which thereby infect it, you should go for x-ray & even extraction of the same tooth if dentist feels that prognosis is poor. Take Care. </s>