When a 6.5x4(3) mm abutment is placed, an immediate provisional is fabricated (Fig.6) with its margin placed subgingival (inset dashed line).  This innovated design of the provisional is to prevent collapse of the most coronal gingiva and loss of bone graft, particularly where the bony plate is defective. 

Repair Sinus Membrane Perforation

Xin Wei, DDS, PhD, MS 1st edition 12/29/2016, last revision 01/19/2018