Extractions are warranted when a tooth is deemed "non-restorable", meaning that there is nothing that we can do to restore the tooth to proper health. The tooth is either too broken or decayed to repair, or there is a severe case of periodontal disease present that compromises the tooth to such a degree that any attempts at restoring it would be futile. In any of these instances, the tooth must be removed.
If you are interested in replacing your missing tooth with either a bridge or a dental implant, make sure you mention this concern with the dentist prior to your tooth being removed. Sometimes there is work that must be done before tooth removal if you are wanting to replace the tooth with a prosthesis after removal.