The maxillary sinus is a natural hollow structure within the bone of the upper face. It is surrounded above by the eye socket, towards the middle by the nasal cavity, and below by the roots of the premolars and molars of the upper jaw. The actual function of the maxillary sinus is unknown. Some scientists believe that the sinuses were important at one time for communication prior to the evolution of modern man. Other scientists and anatomists believe that the sinuses act as “shock absorbers” for the brain during incidences of head and neck trauma. The maxillary sinus is relatively small in size in the newborn and continues to expand until a person reaches 25 years of age. In many cases the maxillary sinus will expand around the roots of the upper premolars and molars. For this reason, when the upper premolars and molars are lost, a sinus graft/lift procedure becomes necessary if one is planning to replace these teeth with dental implants. A typical case is shown below:
The patient’s preoperative x-ray. Previous attempts to save teeth #14 and 15 with root canal therapy failed. This required the removal of teeth #14 and 15. This x-ray was taken 6 months after the removal of these teeth.
The maxillary sinus is labeled in blue and the floor of the sinus is outlined in yellow. This illustration shows that there is not enough existing vertical height of bone to accommodate the implants (red rectangles) designated to replace teeth #14 and 15.
The patient underwent simultaneous sinus grafting and implant placement. Simultaneous implant placement requires adequate thickness and height (3mm) of preexisting bone. If there is not enough existing bone for implant placement, the grafting procedure would be performed first and the implants placed 6 to 9 months after. In this case the implants are allowed to integrate for 6 months prior to restoration with crowns.
The yellow line demonstrates the original sinus floor. The blue line demonstrates the surgical elevation of the sinus floor to allow room for the dental implants. Particulate bone graft material has been used to fill in the void below the elevated sinus floor. Note the newly created “dome” of bone that now exists over the original sinus floor.