"A key to implant success is the quantity and quality of the bone where the implant is to be placed. The upper back jaw has traditionally been one of the most difficult areas to successfully place dental implants due to insufficient bone quantity and quality and the close proximity to the sinus. If you've lost bone in that area due to reasons such as periodontal disease or tooth loss, you may be left without enough bone to place implants.
Sinus augmentation can help correct this problem by raising the sinus floor and developing bone for the placement of dental implants. Several techniques can be used to raise the sinus and allow for new bone to form. In one common technique, an incision is made to expose the bone. Then a small circle is cut into the bone. This bony piece is lifted into the sinus cavity, much like a trap door, and the space underneath is filled with bone graft material. Your periodontist can explain your options for graft materials, which can regenerate lost bone and tissue.
Finally, the incision is closed and healing is allowed to take place. Depending on your individual needs, the bone usually will be allowed to develop for about four to 12 months before implants can be placed. After the implants are placed, an additional healing period is required. In some cases, the implant can be placed at the same time the sinus is augmented."1
1."What Is a Periodontist?"Http://www.perio.org. American Academy of Periodontology, 24 Feb. 2011. Web. 11 Apr. 2012.