A major factor for implant success is the quantity and the quality of the bone where the implant needs to be placed. The issue with placing implants in the back of the mouth for the upper jaws is the location of the sinus. Implants need to be placed in a certain amount of 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 does decrease the volume of the sinus cavity but it is rarely ever an issue.