The abutment at #4 is loose >1 year post cementation.  The abutment remains incompletely seated (gap and longer apical space (double arrows) when the abutment/crown complex rotates lingual mesiobuccal post proximal reduction (Fig.14 curved arrow). 

Setback Last Next  Xin Wei, DDS, PhD, MS 1st edition 03/12/2021, last revision 03/14/2021