When the maxillary sinus floor is missing, the wall of the maxillary sinus floor will drop to the position of the original root of the missing tooth, and the alveolar ridge is atrophied and the maxillary sinus is pneumatized, resulting in insufficient height from the maxillary sinus floor to the top of the alveolar ridge. The implantation of a dental implant. Maxillary sinus lift is the process of elevating the maxillary sinus floor and placing bone graft material between the newly formed sinus floor and the original maxillary sinus floor, increasing the height of the maxillary sinus floor to the top of the alveolar ridge. The history of maxillary sinus floor lift: In the 1960s, Dr. Boyne published the Caldwell-Luc method of maxillary sinus lift with autologous bone graft. In the mid-1970s, Tatum proposed an open maxillary sinus floor lift using autologous bone to elevate the maxillary sinus floor with simultaneous implant placement. Boyne and James were the first to formally document maxillary sinus floor elevation in the literature. (J Oral Surgery 1980;38;613-616) Summers published the osteotome technique as a method of maxillary sinus floor lift in 1994. In 1998, Linno was the first to report on maxillary sinus elevation in China, which led to a much higher success rate of implantation in this area and became a safe area for routine implant restoration. Open maxillary sinus floor elevation Open maxillary sinus floor elevation (external elevation) refers to opening a window at the anterolateral wall of the maxillary sinus, peeling and elevating the maxillary sinus mucosa from the maxillary sinus bone wall with a special tool, placing a bone graft or artificial bone powder between the elevated maxillary sinus floor and the original sinus floor, and implants can be placed at the same time or in stages. Open maxillary sinus floor lift Advantages: the procedure can be performed under direct vision, sufficient bone volume can be created Sinus membrane damage can be easily treated The height of the elevated maxillary sinus floor is high and easy to control, mostly used in cases where the bone height of the posterior maxillary implant area is <5 mm. Disadvantages of open maxillary sinus floor lift: wide range of surgery, more damage, heavy postoperative reaction, high cost, not easy for patients to accept The surgery is difficult because the natural roots of maxillary premolar and molar teeth in the maxillary sinus area are often located in the maxillary sinus cavity, the mucosa of the maxillary sinus wraps around the roots, the alignment is irregular, coupled with the unevenness of the maxillary sinus itself, a single tooth missing or spaced tooth missing when performing maxillary sinus floor lift, affected by its near The influence of the adjacent tooth roots in the distant and middle, it is quite difficult to peel off the maxillary sinus mucosa completely and without damage. The open maxillary sinus floor lift is generally divided into: (1) infracture osteotomy technique; (2) antrostomy osteotomy technique; (3) grinding technique Currently, the infracture osteotomy technique is often used. (2) antrostomy ostrotomy technique; (3) grinding technique, the infracture osteotomy technique is often used, in which the open bone slice is pushed inward as a base to form a new maxillary sinus floor, and the original sinus floor is filled with bone graft material, also known as the trap door method. 9) Suture and post-surgical treatment Open maxillary sinus floor lift - incisional flap Incisional flap: A mucoperiosteal incision is routinely made on the palatal side of the alveolar ridge, and the incision should be more than 2 mm from the margin of the window, with the proximal incision extending in the direction of the buccal vestibular sulcus and crossing the vestibular sulcus, and the distal incision can be extended to the maxillary tubercle area. Open maxillary sinus floor lift - windowing Bone window preparation: The windowing line is determined on the anterior wall of the maxillary sinus above the edentulous space with a ball drill or ultrasonic bone knife. Position of the window opening: the anterior border is 2~3mm from the proximal middle wall of the maxillary sinus, the lower border is 3~4mm from the maxillary sinus floor, the horizontal distance is 10~12mm, and the vertical height is 5~7mm, which can be adjusted according to the size of the implant. The shapes are round, rectangular and oval, and oval is generally thought to be better. Open maxillary sinus floor lift - peeling Separate maxillary sinus mucosa: Gently tap or vibrate with ultrasonic bone knife to make the bone window inward, carefully peel off the sinus floor, inner, outer, anterior and posterior wall under part of the sinus mucosa with special instruments, together with the open window bone plate rotated inward and upward to become the top of the bone implant area in the upper collar sinus, choose the appropriate sinus membrane peeler, meticulously Select the appropriate sinus membrane stripper, carefully peel off the mucosa of the maxillary sinus floor completely, and push it upward to gradually reach the required lifting height. Open maxillary sinus floor lift - bone implant Autologous bone Artificial bone powder Composite bone Open maxillary sinus floor lift - implant Original bone height >=5mm: implant placement at the same time Original bone height <5mm: first close the incision and after 4-6 months or more Implantation.