A dental implant is essentially an artificial tooth root which is attached to the jaw bone. Eventually, a replacement tooth or bridge will be firmly fixed to this root, restoring complete function to the tooth. The key to a successful and long-lasting implant is the quality and quantity of jawbone to which the implant will be attached.
The maxillary sinus is an air filled cavity located on both sides of the upper jaw in the area of the upper premolars and molars. After teeth are lost in this area, bone loss occurs from a combination of enlargement of the sinus as well as loss of the bone in the mouth. If a small amount of bone loss has occurred, the bone in the mouth can usually be "pushed up" into the sinus in order to "indirectly" raise the floor of the sinus to allow for placement of a longer implant and new bone formation.
In a less common sinus augmentation technique, a tiny incision is made near the upper premolar or molar region to expose the jawbone. A small opening is cut into the bone and the membrane lining the sinus on the other side of the opening is gently pushed upward. The underlying space is filled with bone graft material and the incision is closed. The bone which is used for this procedure may be from your own body or from a cadaver (which is irradiated and freeze-dried to eliminate risk of infectious disease). Sometimes the surgeon might use synthetic materials which can also stimulate bone formation. The implants are placed after healing has occurred; this will depend on the individual case.
In both techniques, sinus augmentation has been shown to increase the success of dental implant procedures.