While there may be a number of reasons for wanting a greater volume of bone in the posterior maxilla, the most common reason in contemporary dental treatment planning is to prepare the site for the future placement of dental implants.

What may cause the lowering of the sinuses?

Several different factors may cause the lowering of the sinuses:

1. Long-term tooth loss without the required treatment

   When a natural tooth is lost due to dental decay, periodontal disease, or dental trauma, the alveolar process begins to remodel.

   The toothless area (termed edentulous ridge) will usually lose both height and width over time. Furthermore, the level of the maxillary sinus floor gradually becomes lower.

   

   
   

   In advanced stages of periodontal disease, bone loss is typically higher.

   Overall, this leads to a loss of bone volume that is available for implantation of dental implants, which rely on osseointegration.

2. Inflammation of the maxillary sinuses

   Sometimes, an inflammatory condition of the maxillary sinuses (called sinusitis) may lead to bone resorption and the lowering of the sinus floor.

3. Congenital disorders

   Some patients may have the maxillary sinuses enlarged from birth due to a genetic defect.

4. Other causes

   Other causes can include enhanced bone resorption at this level, missing teeth due to genetics or birth defects, or trauma.

Surgical procedure

Sinus augmentation (sinus lift) is performed when the floor of the sinus is too close to an area where dental implants are to be placed. This procedure ensures a secure place for the implants while protecting the sinus.

a clinical situation where sinus lift is indicated

Preparation

Prior to undergoing sinus augmentation, diagnostics are run to determine the health of the patient's sinuses, general health, and other local conditions.

Panoramic radiographs are taken to map out the patient's upper jaw and sinuses. CT scan is taken to measure the sinus's height and width and to rule out any sinus disease or pathology.

Technique

All procedures involve bone grafting, which adds bone volume to the sinus floor. Various materials may be utilized:

• autogenous bone: a bone graft taken from elsewhere on the individual's body, e.g., the back of the head, iliac crest, etc
• biomaterials: artificial substances that replace human bone, e.g., calcium sulfate, hydroxyapatite

Operation explained

Typically, the procedure is performed under general anesthesia.

1. Tooth loss leads to bone loss.

2. Over time, the sinus will expand into the area previously occupied by bone and teeth.

3. If a dental implant is placed into inadequate bone, it will move, shift, and eventually fail.

4. The sinus lift procedure begins with a temporary opening in one of the two possible areas.

5. With a surgical instrument, the sinus membrane is carefully lifted to its previous position, providing clearance for the placement of the substitute bone (the bone graft).

6. Adequate bone is placed to provide support for the dental implant.

7. Over time, the implant and substitute bone will heal, creating a solid bond.

8. The implant-supported crown has a stable foundation.

Now, let's see how the maxillary sinus looks before and after the procedure:

before

after

Sinus lift complications

A major risk of a sinus augmentation is that the sinus membrane could be pierced or ripped (most often during step 5). Should this occur, the therapeutic remedies include stitching the tear or placing a patch over it.

In some cases, the surgery is stopped altogether, and the tear is given time to heal. The sinus membrane often grows back thicker and more robust, making success more likely on the second operation.

Other risks include infection, inflammation, hematoma, pain, graft failure, or sinusitis.