Another option could be a post crown. The tooth already has endo done on it. The dentist drills out a cavity in the remaining core of the tooth, and down into the roots. A direct resin pattern of all this is made, invested to make a mold, the resin burned out of the mold and and cast in gold. Now you have a perfect gold post that fits directly into the preparation, that can be cemented into place. This is then cemented into the prepared tooth and roots, giving strength to the tooth which would then take the load of a conventional bridge. This is a very old technique. It is cost effective, the tooth which is actually dead after the root canal, is actually like an implant. It becomes ankelosed into the bone without a vital core or periodontal ligament. Even the Sharpies fibers that allow the micro movement of a tooth within its boney socket become desiccated, and the thing is essentially the same as an osteointegrated titanium implant. The gold core gives it the strength of the metal since endodontically treated teeth are naturally brittle. I have seen post and core restorations like this done even when the entire crown of the tooth has been lost, and all that remains are the two or three roots of a remaining molar. It's worth a discussion as an option.