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Zygomatic implants have been documented as a an alternative for the rehabilitation of the atrophic posterior maxilla with both the classical two stage and immediate loading protocols. Zygomatic implants avoid grafting and sinus lift procedures and therefore contribute to a shorter and more comfortable treatment. Further indications for zygomatic implants include failed conventional implant placement, failed sinus augmentation or grafting procedures, rehabilitation after tumor and trauma resections.
In the atrophic posterior maxilla, in general one zygomatic implant is placed on each side of the maxilla, in combination with 2-4 conventional implants in the anterior region.
For the totally resorbed maxilla, when placement of anterior implants is not possible the concept can be expanded by inserting 2 additional zygomatic implants in a more anterior position (Quad zygoma). Zygomatic implants nowadays are usually immediately loaded with a fixed bridge.
In the classical protocol, zygomatic implants are inserted through the alveolar crest and maxillary sinus involving the zygomatic bone for anchorage (Fig 1). For visualization of the correct implant position access to the maxillary sinus is necessary. Access preparation to the maxillary sinus is performed at a lateral posterior aspect at the later implant position and the Schneiderian membrane is elevated in an anterior direction. The implant is placed subsequently and is located at the inner aspect of the sinus wall, often without membrane perforation (Fig 2).
Alternatively the extra sinus placement approach has been described in order to reduce incidence of sinus complications and to improve the implant location and position of the emergence profile more crest ally.
Due to the long drilling distance to the zygomatic bone and in order to protect critical adjacent anatomical structures, placement of zygomatic implants requires considerable surgical training and experience and meticulous diagnostic planning. To receive an adequate overview over the anatomical structures, pre surgical 3D planning with CT or CBCT scans is a must.
The drill protocol is applied in order to achieve an implant insertion torque between 35-45 Ncm in all bone densities for optimal primary stability in immediate function protocols. Use of optional drill steps such as the twist step drills are recommended in case the insertion torque is surpassing 45 Ncm.
Caution: Never exceed an insertion torque of 45 Ncm. Overtightening may lead to damaging of the implant and fracture or necrosis of the bone.