Hello,
Fixed bridges used to replace missing teeth need strong abutment teeth to support the empty span. How long is the empty span? The straighter these abutment teeth are and good bone support are important factors. Your overall bite stability is a factor as well. Keep in mind that most insurance will have a period of time, often five years, that they will not pay for a replacement bridge again. This is a question to ask your treating dentist. I need more details, such as location, how many missing teeth, condition of remaining teeth, your gum and bone condition to give you a better opinion. Have you given consideration to implants? If you are not replacing a bridge or the teeth near the empty area do not require crowns by themselves, I would encourage you to discuss this option. You are wise to get multiple opinions. You may ask the dentist to show you models of your teeth and go over any concerns with bridge placement. This will help you visualize your bridge. I do think Ante's Law is an important factor. This will generally determine how many abutment teeth are needed to be included in the bridge. Your bite and the stress on your bite all factor into how well the bridge will work for you. You should include an additional tooth now if there is doubt about how well the bridge will last. I would be glad to assist you with additional questions. I hope my opinion has been useful and assists you with your treatment decision.