This is a real human skull specimen. You can see how the teeth are set into the upper and lower jaws. There is one section in the middle that we are going to lift up to show you what the sinus looks like. After a section of the bone is lifted, you can see the size of the sinus which is a hole in the skull above the teeth, and it extends down to the roots of the teeth. In one area, the sinus drops down lower and there is not enough bone where the probe is spaced to put an implant. In the adjacent area, there is adequate bone. So the sinus and bone need to be lifted by compressing up and filling in with additional bone before the implant is placed.