Since the tooth #31 is mesially shifted and tilted with mobility, it would be a good distal anchor tooth for #30 implant placement with a surgical guide. It is extracted when an implant is placed at #3 so that autogenous bone harvested from the osteotomy at #3 will be mixed with allograft (Vanilla) and alloplast (Osteogen) for #31 socket preservation (Fig.3 M).
Xin Wei, DDS, PhD, MS 1st edition 09/20/2019, last revision 09/20/2019