The tooth #30 has severe buccal bone loss (especially mesial, Fig.3) and gingival recession.  Fig.4 is an axial section showing that the lingual (L) portion of the mesial (M) root has bony support (periodontal ligament). 

Mesial Sheath     Last     Next

Xin Wei, DDS, PhD, MS 1st edition 05/07/2020, last revision 05/07/2020