The following images from Ebisu Esthetic Implant Institute, Tokyo, illustrate the problem of inadequate bone volume in the back of the upper jaw most admirably. As is with any other site, maxillary implants require bone for early stability and final integration. The maxillary sinus (antrum) is a soft tissue lined air-filled cavity that should not be interfered with by non-native structures.
Unlike the first image where there is adequate bone, the second image shows insufficient amount of bone and placement of the same sized implant will lead to potential sinus complications. Occasionally a shorter implant is adequate but often a sinus lift / sinus graft procedure is mandatory.
WHAT IS SINUS LIFT SURGERY?
For all intents and purposes the procedure of sinus augmentation, sinus lifting, or sinus grafting is used interchangeably and is intended to allow sufficient bone between the sinus lining and the gum lining the jaw bone to admit an implant safely. The principle is to lift the sinus lining intact away from the bone and fill the resultant space with bone. That is to say, the sinus membrane has to be “lifted.”
There are two main kinds; open or closed. Also the bone that is used can be in chips, as a block or a combination there of.
Dr Younessi prefers, when possible, to use a block piece of bone from your own body for its safety, predictability and the inherent ease of the technique. In preparation, there is need for assessment of both the donor and the recipient sites, appropriate X Ray examination which in the more modern setting typically means a Cone Beam CT scan. This imaging modality allows for three-dimensional examination of the appropriate structures.
Less often a blood test or nuclear medicine studies may be needed to assess your bone’s suitability.
The usual approach is for Dr Younessi to make appropriate cuts to expose the jaw bone through the mouth lining and then make a trap-door window into the erstwhile bone of the side wall of the sinus which is hinged into the sinus taking the sinus lining with it. The graft bone is usually secured as the proverbial meat of the sandwich with the old side wall (now roof) and the floor being “bread” slices and the graft bone “meat” of this imaginary sandwich.
There is an absolute need for meticulous mouth hygiene post-operatively and not all grafted bone always “takes”, accordingly Dr Younessi usually “over-grafts” to account for this imprecision.
Some six months later, the bone graft is checked with an X Ray and the fixation screws used to hold the bone graft are released. The site is now ready for implant placement.
As with any other procedure, infection is the main risk. Non-take of graft is not common but certainly possible. There are often recourses.