The head has many sinuses, which are cavities within the head which clean and warm air. The cavities have a very thin lining. Think of the cavity as a thick balloon and the lining as a thin balloon within the cavity. In the upper jaw, above the molars and sometimes premolars there is a sinus, maxillary sinus. When these teeth have been lost and implants are planed as replacements, often this sinus cavity needs to be treated because there is not enough residual vertical bone height to completely cover the implant. To have the proper implant length a sinus lift is frequently needed so the implant does not perforate into the sinus cavity, thin balloon. The implant needs to be fully surrounded by bone; it cannot reside in an air space. A sinus lift will provide for this additional vertical bone, which will cover the top portion of the implant. The procedure is performed by detaching and lifting away the lining of the maxillary sinus from its connection to bone without tearing the lining. It is similar carefully removing a portion of the hard shell of an egg (outer thick balloon) and keeping the soft lining (thin balloon) behind the shell intact. The thin lining is then freed internally from the surrounding shell, enabling that lining to be displaced into the egg. This process creates a space. In a sinus lift, the space is then filled with a bone graft. In a few months your own bone will replace this graft and there will be enough vertical bone to fully surround an implant.
The most common method of performing this procedure is called an internal sinus lift. With traditional techniques, the dental professional performing this procedure is, in essence, going in blind. He/she cannot clearly visualize the sinus lining. Studies show that the sinus lining is perforated up to 30% of the time. Although the lining can be repaired, obviously the preference is not to puncture the sinus lining in the first place.
Fortunately, with the use of the microscope, vision is significantly enhanced, allowing for a sharp and detailed view of the sinus lining and its connection to bone. Manipulation of this very thin membrane can be more carefully implemented, significantly decreasing the risk of sinus perforation. A microsurgical approach leads to a higher level of quality of care, fewer complications and more predictable treatment outcomes.