I recently saw a video demonstration of bone augmentation on You Tube in which the surgeon used calcium phosphate, during GBR, to replace lost bone. The material was delivered to the defect in the bone and no membrane was used to cover it. The surgeon explained that the calcium phosphate surface acted like a membrane itself and epithelium cannot invade. Is this true? I wanted to get your views on this. For those of you who use calcium phosphate for bone augmentation, do you cover it with a membrane or leave it uncovered?