TRANSCRIPT:

An understanding of anatomy is important for not only a successful surgery but also to help prevent complications and to understand where complications are occurring and what adjacent structures they can affect when they do occur.

Let's start by understanding anatomically what the maxillary sinus is. The maxillary sinus is one of the paranasal sinuses. It's an air-filled cavity that sits adjacent to the nose and is lined with respiratory epithelium, communicating with the nose, which is very important.

Secondly, let's understand from an anatomical point why we need a sinus lift. As dentition is lost in the posterior maxilla, the maxillary bone begins to atrophy or shrink. The maxillary sinus begins to subsequently pneumatize or increase in volume. This increase in volume, coupled with the atrophy of the maxillary bone, leads to inadequate bone height for dental implant placement, often affecting bone width as well. Therefore, we often need to consider something like a sinus lift to allow for implant placement in the posterior maxilla.

Now that we understand what the maxillary sinus is and why we have to perform sinus lifts to allow for implant placement, let's look at the structures that are adjacent to the maxillary sinus and understand better the anatomical territory that we will be working in.

We're going to look at the sinus from an inferior, medial, lateral, superior, and posterior view. All of these viewpoints reveal different anatomical structures that are important and have a relationship with the maxillary sinus.

The view here is going to touch on the three viewpoints that are considered most important. The first anatomical relationship highlighted is that the maxillary sinus sits superior to the alveolar crest and the dentition. This is a crucial point to understand, especially when working around roots of adjacent teeth to prevent damage to them during surgery.

The second relationship highlighted is that the maxillary sinus sits medial to the lateral nasal wall. This is important because there's something called the osteomeatal complex, a passageway that goes through the maxillary sinus to the nose, which is vital for proper drainage and preventing sinusitis and infection.

The third view shows the relationship between the maxillary sinus and the orbit, where the eyeball sits. Understanding this relationship is important because an active sinus infection can communicate with the orbit, causing infection in the ocular region and, in severe cases, affecting vision and potentially leading to life-threatening infections. This relationship should be monitored when noticing periorbital inflammation or infection following a sinus lift or graft.

Second, it's important to understand that the sinus sits just below the orbit because when doing an indirect sinus lift, a slip or malfunction of instrumentation can actually pop through and penetrate into the orbit. Again, not common and shouldn't happen if done properly, and we're going to talk about how to prevent that. That is important to understand the proximity of that important structure to the sinus.

The second view that we're going to see here is an axial image on CT scan highlighting the maxillary sinuses. The sinuses are outlined in purple and seen here. What this view shows us is a reminder that the maxillary sinus sits anterior to the pterygomaxillary region. The pterygomaxillary region is the union of the pterygoid plates, the posterior maxilla, the hard palate, and it separates the sinus from the infratemporal fossa. There are a lot of major structures and vessels that lie in this region, but none that should be encountered as long as we stay within the confines of the sinus during our surgery.

Last, this view shows us that the maxillary sinus sits medial to the zygoma and the zygomatical maxillary buttress, which is the union of the zygoma with the maxilla. This more than anything is just an identification point during your access when you're making your bony window, ensuring that you are anterior to the union of the zygoma and the maxilla as a good guide to proper placement of your bony window.

Lesson Summary

An understanding of anatomy is crucial for successful surgery and to prevent complications. A knowledge of adjacent structures is important to understand where complications may occur.

The maxillary sinus is one of the paranasal sinuses, an air-filled cavity next to the nose that communicates with it. A sinus lift may be necessary when dentition is lost in the posterior maxilla and the maxillary bone starts to atrophy, causing the maxillary sinus to increase in volume. This can result in inadequate bone height and width for dental implant placement, necessitating a sinus lift.

Adjacent to the maxillary sinus are several structures that are important to consider during surgery:

• The maxillary sinus sits superior to the alveolar crest and the dentition, so working around roots of adjacent teeth is important to prevent damage.
• The maxillary sinus is medial to the lateral nasal wall, and there is an important passageway called the osteomeatal complex that goes through the sinus to the nose. This passageway is vital for proper drainage and should be kept patent to prevent sinusitis and infection.
• The maxillary sinus is also related to the orbit, where the eyeball sits. An active sinus infection can communicate with the orbit, causing infection in the ocular region and potentially leading to vision problems or serious infections. Inadvertent penetration of the sinus into the orbit during surgery should be avoided.
• In CT scans, the maxillary sinus is seen anterior to the pterygomaxillary region, which includes the pterygoid plates, posterior maxilla, and hard palate. This region separates the sinus from the infratemporal fossa. Care should be taken to stay within the sinus during surgery to avoid encountering major structures and vessels in this region.
• The maxillary sinus is medial to the zygoma and the zygomatical maxillary buttress, the union of the zygoma with the maxilla. Proper placement of the bony window during surgery should be anterior to this union.