In the early 1980s it was shown that bone from the skull, (membranous bone), maintained its volume to a significantly greater extent than bone from the rib and iliac crest regions, (endochondral bone). However, the reason for this enhanced volume maintenance was not clarified for many years.On the basis of this enhanced volume maintenance, cranial bone became the ideal autogenous graft of choice for hard tissue repair.In the ensuing years, the current authors performed a large number of autogenous split skull cranial bone cranioplasties with significant success. However, the lure of an off-the-shelf material that obviates bone harvest remained.From 1995 to 2005 the senior author performed twenty full-thickness skull defect cranioplasty corrections using calcium phosphate cement (Norian). Of these full-thickness defects, 16 were large (arbitrarily defined as greater than 25 cm2). In this paper, we report our long-term major and minor complication rate using this material. Due to our high, long-term complication rate (38%), we believe this material is contraindicated for large, full-thickness, skull defects (greater than 25 cm2) and we have returned to autogenous cranial bone as the gold standard for reconstruction of such patients.