When a 6.5x4(3) mm abutment is placed, the localized bulging plate fractures (Fig.5 *) with resultant mesiobuccal thread exposure (Fig.6).

Suctioning well while the abutment is being placed may prevent the fracturing.  Or a smaller abutment with longer cuff may be another preventive measure.

1-Staged Ridge Split Last Next Xin Wei, DDS, PhD, MS 1st edition 01/27/2016, last revision 07/27/2018