Although the lateral sinus floor elevation is a proven clinically successful technique [14], the indirect SFE approach is favorable among clinicians because it does not require a second surgery site and hence cause less trauma and discomfort for the patient [14,15,16]. However, this method has its drawbacks, such as a higher risk of membrane perforation, a decreased space for using surgical instruments, and limitation in elevation heights when using the conventional techniques [3, 16, 17].

The osteotome technique originally described by Tatum 1994 has been shown microscopically to elevate the sinus floor for 5 mm without causing perforations [18]. Thus, this technique should not be used when the intended elevation height is more than 5 mm [19]. Therefore, a need for transalveolar approach that can elevate the membrane safely and for elevation heights greater than 5 mm has risen, Tatum described a modified approach to his osteotome technique in which bone particles are pushed in the sinus. The addition of bone will prevent direct contact between the instruments and the membrane [20]. Recently, many methods for SFE have been described as an alternative for the osteotome technique. Most of this techniques fall under two categories: using an inflatable device such as a balloon or using hydraulic pressure, both of which have been shown to reduce the rate of membrane perforation [6, 7, 13, 21, 22]. Soltan and Smiler described the use of the balloon and concluded that it is a highly successful and easy to perform procedure [6]. Recently, many systems have been developed which rely on hydraulic pressure to lift the sinus mucosa including the Jeder-System (Jeder GmbH, Vienna, Austria) which consists of a drill with a chamber which is filled with saline solution. After the initial drilling is done, the drill is connected to a pump that produces high hydraulic pressure; the pressure is used to break the sinus floor and to lift the membrane [23]. Also, OSSTEM implants introduced the CAS kit as a method for preparing the osteotomy and elevating the membrane through hydraulic pressure.