Black line around my natural back tooth with terrible ordor and taste come from it. also i just went to dentist for cleaning, do i need a new one?

Depends: If you told your dentist that you were concerned about the black line around your tooth and we're experiencing a terrible odor and taste coming from the tooth during your recent visit, and your dentist ignored your concerns and did not address it, changing dentists may not be a bad idea.

Unknown: The tooth should be reexamined by the dentist and/or hygienist. There should be no buildup of calculus or staining if you just had a cleaning. The odor may or may not be coming from that tooth. Your concerns should be directed to your treating dentist.