After incision at #21 (Fig.1) and flap elevation, the narrow ridge is to be reduced and initial osteotomy is to be made over the widened ridge (Fig.2,3). The bone loss in the mesiobuccal area (*) appears to be the most severe.
Xin Wei, DDS, PhD, MS 1st edition 08/06/2018, last revision 08/06/2018