I almost guarantee that the bridge is in cross bite and thus the occlusion is poor. Usually the wisdom teeth alignment is more toward the buccal and should NEVER be used as an abutment for a bridge, not to mention four unit bridges. All you need is the first molar, thus you only have to place one implant to replace the first molar. There is no need to replace the second molar, since it only plays a minor role in function (5% chewing efficiency). Moreover, you can never floss the upper bridge and thus it probably only last five years. I would predict it would start bleeding on the gum within one year, then you may have foul smell from the area. Even if you did the root canal, it would be unpredictable and would likely to fail within five years. Very seldom people do root canal on the wisdom teeth. I would like to say NEVER. Now this is a solution to your problem. Let''''s cut off the bridge, ask for the money back as fast as you can (if you delay for couple months you will not be able to), you can keep the crown on the premolar. Place an implant on number 3 (first molar) and that is it. At our office we guarantee the implant lifetime. We have over a thousand case to show to you. And we also have a CT SCAN on board if you ever need it (we only charge 99.00 for a CT SCan). Please visit our office for a consultation. The reason why you have sensitivity is due to poor occlusion, poor marginal fitting due to wisdom teeth, and poor access to oral hygiene.