The hard tissue ridge is approximately 3 and 5 mm buccolingually at the sites of #28 and 29, respectively (Fig.3 after initial osteotomy: 1.5 and 2.0 mm). 

From Removable to Fixed Prosthesis

Xin Wei, DDS, PhD, MS 1st edition 07/20/2015, last revision 07/20/2015