You are talking about the crown over the tooth #13 after the bridge is cut off, which is called formally retainer (crown).  The tooth is called abutment, which has double meaning (2nd definition).  When the tooth has been prepared for crown or bridge, the axis of it may not the same as that of the root (Fig.1,2).  In fact, we took #13 crown as a guide in surgery.  It fooled us.  Click here and keep clicking somewhere over several pages.  You will find the answer.  Thanks for the try.