If you do not want to use a movable prosthesis in the absence of your molar teeth in the upper jaw, it is a technique of increasing the amount of the bone in order to use a fixed prosthesis (for an implant treatment).
The maxillary sinus is the name given to the anatomical cavities located just above our upper jaw and near to our molar teeth. The task of these cavities is to reduce noise and minimize head weight.
When the sinus cavities are leading downward, there is a decrease in the bone volume between the sinus cavity and the tooth root. While the bone loss can be seen as a naturally occurring physiological phenomenon, it may create problems before implant procedure.
This procedure creates bone volume sufficient for the height and width of the implant to be fully placed in the bone. After a sufficient bone volume is achieved, implants are placed.