Fig. 1

The original surgical technique described by Branemark (OST) begins with a Le Fort I-type incision. A full-thickness mucoperiosteal flap is elevated to provide direct visualization of the trajectory of the implant from the premolar/molar region of the alveolar bone to the zygoma body. The dissection is continued from the lateral wall of the maxilla towards the zygomatic bone to allow for increased visibility of the zygomatic region and the infraorbital nerve. A lateral window of approximately 10 * 5 mm is then made into the lateral aspect of the maxillary sinus using a round bur (A). Once the membrane has been exposed, it should be carefully elevated medially and superiorly. The entrance of the ZI is marked with a round bur on the palatal side of the crest. The drilling sequence starts at the alveolar ridge, passing through the maxillary sinus, and the drill is advanced to reach the body of the zygoma to the desired emergence level (B) [2] (Figure provided by Yiqun Wu)