Have you at some time lost teeth in the posterior region of your upper jaw and have been told there is now a deficiency of bone that prevents you from having dental implants?
The probable reason for the deficiency is not only because of the bone loss where the teeth used to be (alveolar bone) but also because of the location of your maxillary sinus.
What is this maxillary sinus?
It’s an air-filled chamber (referred to as an antrum) on both sides of your upper jaw, located above the posterior teeth roots (which can extend into it), below the eye sockets and extending inwards to the nose into which it communicates, via a hole called the ostium. The ostium drains any fluid build-up which occurs in the sinus; for instance when you have sinusitis.
In even more simple terms; beneath the cheek bones, when the teeth are missing, there is not much solid bone before we fall into an empty air-filled space (i.e. the antrum) and this creates a dilemma for placing dental implants. Fortunately we have developed excellent grafting techniques for placing bone into this part of the antrum and once it heals, will allow the placement of implants
very successfully. It is even possible, on occasion to place the implants and at the same time, graft the sinus surrounding the implants with bone. This does require however sufficient of your own
ungrafted bone below the sinus to properly stabilise the implants so they do not move.
The methodology for a
Sinus Graft procedure involves lifting the gum and making a small lateral window approach into the sinus and placing bone from a donor site and/ or from ‘bone-in-a-bottle’. Following grafting, a membrane is usually placed over the window to allow bony regeneration and healing. There is documented evidence that addition of the product Bio-Oss which is '
bone-in-a-bottle' actually helps to stabilise and improve the quality of the graft and improves the success of implants placed into the sinus.
The air-filled antrum has a thin delicate tissue lining (called the Schneiderian membrane) on its internal walls. It is this lining that becomes swollen and infected producing the fluid associated with sinusitis. This tissue has to be protected and elevated up and out of the way when performing sinus grafts, it also has to be free of infection and inflammation otherwise the graft can become infected and fail.
If this membrane develops a small perforation during the procedure it can be repaired and the graft may still be carried out however on occasion (possibly due to adhesions, unforeseen pathology or surgical difficulty) the membrane can develop a large perforation. If this occurs then unfortunately
the procedure must be abandoned and the grafting will not be carried out. The membrane is allowed to heal and as a general rule the healing process (scarring) makes it much easier to elevate at the next attempt with less risk of perforation.
Sometimes the bone beneath the sinus is adequate for placement of an implant without sinus grafting (for instance the teeth have not long since been extracted) or sometimes there is almost enough bone height but just short of being able to place an implant of adequate length. For these cases and provided the anatomy and health of the sinus is favourable the sinus membrane can be lifted (like a tent pole lifts a tent) through the hole prepared for the implant, graft bone placed and the implant placed. This is called a
Sinus Lift procedure.
If it is suspected that the membrane may have perforated during this procedure then it will be necessary to carry out a conventional sinus graft with a lateral window approach and repair the defect.
Sinus grafting should only be carried out by experienced practitioners with appropriate training, it is not a painful procedure and when it is carried out well it is an extremely successful way to place implants in the upper posterior regions of the jaw.
