The Localized Management of Sinus Floor is a surgical technique for transcrestal maxillary sinus floor elevation. Its aim is to create a surgical site for implants by displacing a portion of native residual below bone within the cavity of the maxillary sinus. This particular type of bone is usually found below the sinus floor and, through this technique, is displaced vertically in order to create a new implant alveolar portion. In the final configuration of the surgically created alveolus, the coronal portion of the crest must give primary implant stability. This will be completed by the coronal bone portion – pushed laterally and internally of the sinus cavity – from which, a sort of closed “tent” formed by the sinus membrane, will keep the cavity closed. The latter will be filled by blood produced by the alveolar walls.
Tissue repair of the peri-implant alveolus is totally entrusted to the physiological mechanism of bone repair on the site chosen for the implant osteotomy. 3-4-13-14
The goal is to change the height of available bone by creating an osteotomy tunnel starting from the crestal position and extending, initially transversally and medially, in a direction parallel to the palatine vault. This way, the osteotomy tunnel pushes the spongy bone against the floor of the maxillary sinus and avoids loss of the precious calcified structure.
The initially transverse direction (and not vertical, according to the normal prosthetic axis) is essential to:
1. Increase the height of native bone, interfacing the implant to improve primary stability;
2. Use the higher portion of the sinus floor which is normally found towards the medial side of the sinus cavity.
Preparation of the surgical field
According to the protocol, the preparation of the soft tissues is made with a partial thickness technique that has the objective to leave a thin layer of connective tissue which:
1. Ensures the integrity of the periosteum;
2. Allows to easily read the underlying bony anatomy.
The protection of the periosteum is critical, of course, to maintain the integrity of the blood supply15. Also the layer of connective tissue, and the interposed periosteum between tissue and bone, will be fundamental to promote the peri-implant tissue secondary intention healing. This is one of the main issues of the protocol.
This preparation enables to firmly anchor the keratinized tissue – using the sub-periosteal sutures – in an apical and vestibular position. This residual displaced tissue, previously covering the crest, has been displaced vestibularly14.
The flap preparation begins with a palatally beveled incision which slides along the bone plane, starting from the palatal angle of the crest, exactly where the palatal structure crosses the horizontal portion of the edentulous ridge. This has the aim of exposing the crest and displacing vestibularly the keratinized crestal residual tissue to the future implant emergency. This crestal tissue is the same one which has been previously moved from the palatal aspect of the surgical field. Fig. 01/05