The posterior maxilla is a challenging area for placement of dental implants due to poor quality and quantity of bone caused by pneumatization of the maxillary sinus. Ironically, posterior maxillary dental implants need to resist much higher functional occlusal forces compared to implants placed in anterior regions. For this reason, the technique of lateral window antrostomy was introduced to the profession by Boyne in 1980. Since then, a host of surgical procedures have been developed including osteotome sinus floor elevation, crestal core elevation, hydraulic, and hydrodynamic floor elevations. Due to development of these safe, effective, and less invasive techniques, lateral window antrostomy technique is being utilized less and less, however, it still plays an important role in certain clinical situations for rehabilitation of posterior maxilla.
The lateral window osteotomy technique provides direct visualization of the sinus membrane/cavity eliminating guesswork involved with subantral crestal techniques and minimizing the rate of undetected membrane perforation rates. Direct visualization of medial wall ensures membrane detachment from the medial wall of the sinus, thereby optimizing the osteogenic potential. Leaving the periosteum of the schneiderian membrane attached to the bone, which frequently occurs during crestal approaches, should be avoided because it is known that the periosteum and the periosteal collar are responsible for bone formation. Once the periosteum has been left attached to the sinus floor, bone regeneration could be obstructed by the lack of delivery of bone morphogenetic protein-2, alkaline phosphatase, osteopontin, osteonectin, and osteocalcin to the augmentation site. Broad detachment of the sinus membrane increases the exposure of this osteogenic periosteal layer, hence, increasing the amount of bone regeneration. But more importantly, broad detachment exposes more bony surfaces that take part in wound healing. By elevating the membrane from the medial wall of the sinus to the height of the lateral window as proposed by Misch, an additional surface area of bone is made available for wound healing. Therefore, it is a technique of choice with or without simultaneous implant placement when the residual alveolar bone is less than 3 to 4 mm, where the utmost osteogenic potential is necessary for predictable implant survivability.
In addition, lateral window osteotomy allows for removal of concurrent sinus pathology such as mucus retention phenomenon, and even allows for retrieval of lost dental implants from the sinus cavity. It is also a “fall-back” technique of choice when a crestal technique is not successful and the case has to be aborted otherwise due to membrane perforation that inhibit further dissection of the sinus membrane. Without any doubt, it is still considered the most versatile technique when dealing with atrophic posterior maxilla, and therefore, a technique clinicians should not neglect to master despite the phenomenal advancement in sinus augmentation techniques.