What is special about this case? 

A 50-year-old lady presents to clinic with chief complaint "I need a new filling in the lower right".  Root canal has been done in her home country without symptoms for several years.  Exam reveals that the tooth #31 has DO composite.  The mesial portion of the restoration has chipped (Fig: black arrowhead).  There is 2nd caries in the distal margin (white arrowhead).  Percussion reveals minimal tenderness.  Crown is recommended.  In addition to the post (P) and core (C), what is special about this case?

Xin Wei, DDS, PhD, MS 1st edition 09/23/2012, last revision 09/24/2012