There is a buccal concavity at #9 (Fig.1 red dashed line).  The 2.5 mm implant at #9 should be placed between the Incisive Canal (Fig.1 I) and the buccal concavity (Fig.4).  The ridge at the buccal concavity (9 C) is too narrow to be suitable for implant placement (Fig.5).

2.5 mm 1-Piece Implants

Xin Wei, DDS, PhD, MS 1st edition 01/21/2017, last revision 01/19/2018