Evaluation of Bone Height Gain Following Trans-crestal Sinus Floor Elevation

Overview

Missing teeth usually result in functional and cosmetic deficits. Traditionally, they have been restored with dentures or fixed bridges. However, dental implants represent an excellent alternative which rely on the maintenance of a direct structural and functional connection between living bone and implant surface, which is termed osseointergration . When sufficient bone is available in maxilla, implant rehabilitation has shown high success rates of 84-92 %. Atrophy of the alveolar crest and pneumatization of the maxillary sinus limits the quality and quantity of residual bone, therefore complicating the placement of implants in the posterior maxillary area.

Among the techniques used to overcome low vertical bone height in the maxilla is maxillary sinus floor augmentation. It can be performed either through a lateral window, or via a crestal access. Many long term studies and systematic reviews have showed that osteotome mediated sinus floor elevation (OSFE) technique is a highly predictable method for rehabilitation of patients with atrophied posterior maxilla with survival rates ranging from 92 % to 100 %. However, endoscopic studies have demonstrated the risk of membrane perforation while performing transalveolar sinus floor elevation. Moreover, the Summers technique can cause some complications as headache and paroxysmal positional vertigo. Additionally, the activity of osteotomes during the application of malleting pressure is difficult to control, resulting in unwanted instrument and/or graft penetration into the sinus cavity, potentially causing membrane penetration. However, Huwais invented a new technology termed osseodensification for enhancing implant primary stability in 2015. This technology is performed with the use of specially developed drill bits (Densah burs) that combine the benefits of osteotomes with tactile control during the expansion. They have four or more lands with a negative rake angle, which prevents the bur's edges from cutting the bone and so compacts it smoothly. These drills have a tapered shank and a cutting chisel edge. They can thus go deeper into the osteotomy site, while the drill's gradually increasing diameter aids in the site's gradual enlargement. Drills are utilized to enter into the bone in a clockwise rotation (Cutting mode) until the appropriate depth of the osteotomy is reached. Afterwards, counterclockwise rotations (Densifying mode) generate a robust and dense layer of bone tissue along the osteotomy's walls and base. Through controlled deformation, this procedure burnishes bone along the inner layer of the osteotomy site. The goal is to construct a condensed layer of autografted bone along the implant's periphery and apex. This would improve the bone-implant contact, hence increasing insertion torque values and, as a result, implant primary stability.