The success of an implant is largely dependent upon the quantity and quality of the bone where the implant needs to be placed. A big issue when placing implants in the back of the mouth in the upper jaw is the location of the sinus. Implants need to be placed in bone and they cannot be placed into the sinus cavity. Since the sinus is a membrane, it can be lifted and displaced by bone in a procedure called a sinus lift or sinus augmentation. This decreases the volume of the sinus cavity, but this rarely causes problems.