Sinus Lift: How to Increase Safety and Reduce Complications

What is it?

Maxillary sinus augmentation (or sinus lift) is a very effective surgical procedure used to increase bone in the posterior maxilla and therefore allow placement of dental implants. The complications most frequently encountered during this type of surgery are: laceration of an intraosseous artery (causing bleeding) and perforation of the Schneiderian membrane (the membrane lining the maxillary sinus cavity).  In case of bleeding, the procedure has to be suspended (sometimes aborted) until the bleeding is controlled. In case of perforation of the Schneiderian membrane, a repair must be attempted, increasing considerably the length of the procedure and consequently the post-operative discomfort and incidence of complications. The conventional technique for maxillary sinus augmentation involves the use of a high-speed hand-piece for the removal of the thin cortical plate that constitutes the lateral wall of the maxillary sinus. In the vast majority of the cases this bony wall is <1mm (Neiva et al 2004). With the conventional technique, perforation of the Schneiderian membrane occurs in ~40% of the sinus lift procedures. I recently co-developed a technique (Geminiani et al 2011) that significantly reduces the incidence of this type of complications (Weitz et al in press).

How does it work?

Incision Design

Incision design (black line)

Mucoperiosteal Flap Reflection

Lateral wall of the maxillary sinus

Initial lateral window osteotomy

Initial lateral window osteotomy

An undersized osteotomy of the lateral window, frequently leads to perforation of the Schneiderian membrane.

I have noticed that marking the extension of the window helps me in achieving a properly sized osteotomy. I start tracing the inferior border at the level of the maxillary sinus floor, or slightly cranially (~1mm). To do this, I use a reference point (such as the edentulous ridge, or the CEJ of an adjacent tooth) and measurements taken on the pre-operative cone beam CT. Then I proceed tracing the location of the mesial and distal borders. I tend to avoid rotary instruments (such as a high-speed hand-piece) to trace the extensions of the lateral window, unless the pre-operative image show a thick lateral wall (>2mm). Instead, I use an air-driven sonic hand-piece coupled with a dedicated diamond-coated vibrating insert.

Preparation of the lateral window using a vibrating instrument

The diamond-coated sonic instrument (not working)

The diamond-coated sonic insert (vibrating at 6 kHz)

I think the sonic hand-piece is the ideal device for the preparation of the lateral window sinus lift. The diamond-coated insert does not rotate, but vibrates (at 6 kHz). This allows a precise and safe osteotomy, reducing significantly the incidence of perforations (Weitz et al, in press).

Osteotomy of the inferior border, instrument not vibrating (for photographic reasons)

Osteotomy of the inferior border, the diamond-coated insert is vibrating

First, I complete the osteotomy of the inferior border. I follow the tracing previously done (as you can see in the image). The Schneiderian membrane has grayish halo, making it easier to distinguish from the adjacent tissues. The cavitation effect of the sonic instrument produce temporary hemostasis, improving the visibility of the surgical field. Once the inferior border is completed, I proceed to the preparation of the mesial, superior and distal border.

The osteotomy of the lateral window has been completed

Separation of the Schneiderian membrane from the wall of the sinus

The Schneiderian membrane is separated from the bone using the discoid insert (not active for photographic reasons)

This is a critical step. Perforations of the membrane occur frequently during this phase of the sinus lift procedure. To increase safety and reduce complications I use the air-driven sonic hand-piece coupled with the discoid insert. The insert is activated (vibrating and irrigated by the water spray) and then placed between the lateral bone wall and the Schneiderian membrane. The “island” of residual bone can be removed if it does not allow the correct placement of the discoid insert. I start from the superior border of the osteotomy (as shown in the illustration), proceeding mesially, towards the mesio-superior line angle and along the mesial of the window. I proceed to the next step only once I have released the membrane at least 2mm along the superior and mesial border of the window osteotomy.

Elevation of the Schneiderian membrane

Conventional instrument used to release and elevate the sinus membrane.

Once the membrane has been freed using the discoid insert (at least 2 mm), it is much easier to proceed with its elevation and reflection. Most of the time I use conventional hand instruments. Dedicated sonic inserts are available. They are particularly useful when a septum is present, or in case of recent extractions (<90 days). The arrows in the illustration are pointing at the bony wall. It is interesting to observe that the lateral wall of the maxillary sinus tends to get thinner in a caudo-cranial (corono-apical) direction.

The membrane has been reflected to the medial wall

It is important to reflect the membrane up to the medial wall of the maxillary sinus (as shown in the illustration).

Grafting of the maxillary sinus and membrane

Grafting material placed in the subantral cavity

A collagen barrier is placed over the grafting material

The sinus is grafted with the material of choice. I prefer to use a combination of xenograft and allograft, however several kind of grafting materials have been proven effective. Once the graft has been placed in the subantral cavity, the lateral window osteotomy is covered with a collagen membrane. The illustration clearly shows the criteria that I consider important in the placement of the absorbable membrane. The barrier should extend at least 3mm past the border of the window, it should have rounded corners and can be fixated with tacks (to avoid dislodgment). A safety margin of 1-2mm should be left between the tacks and the margin of the barrier, in order to prevent tears.

Flap replacement and suturing technique

Sutures (orange line)

Primary closure is fundamental for the success of this procedure. If primary closure can not be achieved by flap replacement, a periosteal releasing incision is indicated. More details on how to perform a safe and effective periosteal releasing incision can be found in an excellent article recently published (Romanos 2010).

The first suture I place (4-0) is a crossed horizontal mattress. I enter the distal portion of the flap from the buccal and run the suture to the palatal flap. Here, the suture engages the flap twice first from the periosteum towards the epithelial surface (on the mesial aspect), then from the epithelium to the periosteum (on the distal aspect). Then the needle enters the mesial portion of the buccal flap from the periosteum exiting in the buccal vestibule. The suture is closed, the knot should lay on the surface of the buccal flap. I use single interrupted sutures (5-0) for the vertical releasing incision and the beveled mid-crestal incision (4-0 and/or 5-0).

Management of Complications

Perforation of the Schneiderian membrane

The perforation is detected

The osteotomy is enlarged

Separation of the membrane

Membrane folded on itself

Intraosseous artery

Intraosseous arteries intersect the area designed for the preparation of the access window in 15-20% of the sinuses. When this is the case, there are mainly three options: modify the form of the lateral window osteotomy to avoid severing the artery, mobilize and translocate the artery, or abort the procedure  and consider other treatment options.

Intraosseous artery

Artery reflected allowing access to the subantral cavity

Sinus septum

Two separate lateral windows prepared to avoid sinus septum

More info about the author: Alessandro Geminiani, DDS, MSc, MS is a specialist in periodontics and dental implants. His practice focuses on sinus lift (sinus augmentation) and is located in Rochester, NY.
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12 responses to “Sinus Lift: How to Increase Safety and Reduce Complications

    • Hi Ghadateen,
      The grafting materials used for sinus lift are almost always non resorbable. This means they are retained in the sinus forever (or almost, we have data for certain xenografts, the animal bone graft, to last >10yrs).
      Therefore is normal for this materials not to resorb, and that is actually the reason why we use them. We want to preserve the space for a future implant placement.
      If, on the other side, you are referring to infection of the graft material, that is a uncommon complications. In this case all of the grafting material is removed from the sinus, the area is left to heal for a few months and then the procedure can be re-attempted.

  1. Excellent description of your surgery. I have 2 questions:
    1)I noticed that apparently you did not place a resorbable membrane against the lateral surface of the pocket you formed of the released Schneiderian membrane (with the boney island now positioned as the ceiling) before you placed the graft material. Is covering the lateral surface of the membrane not necessary?
    2) I’ve observed a few of these surgeries but the “tacking” of the “corners” of the membrane is new to me. Where can I obtain these “tacks” and how are they placed?
    Thanks

    • HI,
      1) I do not normally place a collagen membrane covering the elevated Schneiderian membrane, unless there is a large perforation (>3mm in radius). If the perforation is small, once the membrane is release and pushed up, it tends to fold on itself and that should be sufficient to “repair” the perforation. If there is no perforation, there is no need to cover the membrane with a collagen membrane. Actually doing so could delay the healing and mineralization of the bone graft. I actually have no data on this, but I base this statement on the fact that the osteoblast (the progenitors of bone formation and mineralization) are located in the periosteum. Specifically in the case of the maxillary sinus, the osteoblast are located in the Schneiderian membrane. Therefore placing a membrane could increase the amount of time needed for the migration of the osteoblast in the bone graft.
      On the other hand, if you have a perforation of the sinus, there is no other option than placing a membrane. Otherwise the graft could be lost through the perforation and result in failure of the procedure, or even worst in the occlusion of the osteum (the sinus opening that allows mucus to drain in the nasal cavity) with risk of sinus infection. This type of complication is very difficult to manage and might require endoscopic surgery to re-open the osteum.
      2) Now that I went back to read the original post, it seems like I place tacks almost every time. On the opposite, I can count on the tip of my fingers the number of times that I “tacked” a collagen membrane for sinus lift. Not very many. I used tacks only when I was concerned the patient could blow the grafting material out of the sinus through the lateral window, or when I had to repair very large perforations.
      Tacks kit are available from several dental suppliers, just to name two: AceSurgical and Salvin Dental. You will find info on their website.
      Tacks come in several length, if I recall correctly 3mm and 7mm. considering that 90% of the time the thickness of the lateral wall of the maxillary sinus is less than 1mm (from Neiva’s paper) you might want to use the short ones.

      Thanks

  2. I have watched my surgeon do this procedure multiple times and he does not use a membrane as he says ” Why use a membrane when you already have the best membrane intact?” ie..periosteum. His surgeries turn out fantastic.

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