Sinus Graft: adding bone to the maxillary sinus for dental implant placement
When your dentist tells you that you need sinus graft, you are most likely to wonder what sinus graft is and why you need sinus graft. Since dental implants are held tightly by bone, dental implants must be placed within bone. In the molar (back teeth) areas of the upper jaw, there are maxillary sinuses. Maxillary sinuses are air-filled spaces within the upper jaw bone. Maxillary sinuses are two of the many sinuses in the head region. Maxillary sinuses are located underneath the eyes and above molar teeth (back teeth). The maxillary sinuses are lined with thin membranes, called Schneiderian membranes.
The maxillary sinus becomes larger in size with age. It tends to enlarge itself, over the area where the molar teeth roots are, especially after the molar teeth are lost. Some dentists gave this enlargement of maxillary sinus after tooth loss a special name, pneumatization. Sometimes the lower bony wall of the sinus becomes very thin, sometimes so thin that there is no appreciable amount of bone left at all, especially in cases where molar teeth has been lost for a long time.
Compare the two x-ray images below. The first image shows enough bone where a dental implant is planned to be placed (the red-line measurement shows 13 mm). In the second image, the measurement shows 4 mm, and a 10- or 12 mm dental implant can not be surrounded by bone in the area.
Enough bone under the Maxillary sinus for dental implants
Not enough bone. Blue arrows indicate the sinus border
Since dental implants are placed in the bone and anchored by bone, areas with little bone presents a problem when dental implants are planned. In order to augment the area, bone can be added either from the sinus side or the oral cavity side. The decision depends on many factors. The grafting of bone from the sinus side is often called sinus lifting or sinus grafting. Dentists usually make small windows into the sinus, carefully lift up the sinus membrane and pack bone graft material under the sinus membrane.
By adding bone at the sinus floor and allowing the graft to take, dental implants of adequate sizes can be placed into the bone in the upper molar areas. After a bone grafting procedure, the grafted area is usually left alone to mature for 6 to 9 months. Sometimes dental implants can be placed simultaneously with sinus grafting.
