Forty patients with partially or fully edentulous atrophic jaws having less than @ mm of residual crestal bone height and/or less than @ mm of bone thickness , as measured on computerised tomography ( CT ) scans , were randomised into two groups according to a parallel group design , either to be augmented with autogenous onlay bone blocks ( @ patients ; AB group ) from the mandibular ramus or the iliac crest , or with onlays blocks of spongious bone of equine origin ( @ patients ; XB group ) .