Songpa-gu Dental Implants: Why Is a Sinus Lift Needed?

Hello. I am Shin Seung-hwan, the director of Yonsei U-Line Dental Clinic, Garak Branch, located in Garak-dong, Songpa-gu, near Garak Market Station.

This time, I would like to explain the additional bone grafting procedure required for dental implant treatment, known as a sinus lift.

Bone grafting is generally performed when there is not enough bone to place an implant. There are two main types of bone deficiency.

One is insufficient bone width where the implant needs to be placed, and the other is insufficient length—in other words, insufficient height.

A sinus lift is particularly needed in the upper jaw, especially around the molars. There is an empty space above the roots in this area, which is called the maxillary sinus.

When placing an implant, the width of the upper jawbone is usually sufficient. Even after a molar is extracted, the bone width often remains adequate unless there was severe inflammation. The problem, however, is the height.

A certain amount of length, or height, is needed to place an implant properly, but there may not be enough. In some cases, only 1–2 mm of bone remains, while in others, somewhat more is available. On average, implants require a length of approximately 8–10 mm.

This means that the patient needs to have roughly that much bone height. However, more people than you might expect do not have enough bone. In particular, in people whose teeth were extracted a long time ago, the maxillary sinus undergoes a process called “pneumatization,” causing the bone to gradually become thinner and decrease.

The maxillary sinus normally allows air to pass through and connects the nasal cavity with the oral cavity. When a tooth is lost, this empty space gradually expands, causing the bone to become thinner and diminish. In some people, only about 1–2 mm of bone remains.

There is also considerable individual variation. Some people have plenty of bone above the tooth roots, while in others, the bone is thin enough that the roots are exposed close to the maxillary sinus from the beginning.

Many patients also wonder, “I’m getting an implant where my tooth used to be, so why are you recommending a sinus lift?”

This is related to the shape of the tooth roots. Molars usually have three roots.

There are two on the outer side and one on the inner side. These roots spread out to both sides around the maxillary sinus. In other words, there was actually an empty space in the middle. The tooth roots supported the area like walls on either side, but after the tooth is extracted, the empty space between them becomes exposed.

So, when you wonder, “I had a tooth there, so why am I being told that I need sinus surgery?” this is usually the reason.

Sinus lift procedures can generally be divided into two types.

The first is used when a sufficient amount of existing bone remains. In this case, additional bone is placed through the opening made for the implant. The procedure is not extensive and is relatively straightforward.

The second is used when only 1–2 mm of bone remains. In this case, a separate window is created on the side, and bone is placed through that opening.

Although the surgical techniques differ, both fundamentally involve a bone grafting process. Some dentists use the first, less invasive method whenever even a small amount of existing bone remains.

Many seminars and professional conferences also commonly recommend accessing through the implant opening when a certain amount of bone is present, and approaching from the side when a large amount of bone must be placed.

A sinus lift does not simply involve placing bone. It also requires lifting the thin membrane inside the maxillary sinus. A space is created between the bone and the membrane, and the graft material is placed in that space.

Over time, this graft material is replaced by the patient’s own bone. The time required varies depending on the amount, but patients generally need to wait four to five months, and in some cases six months or longer.

However, because the maxillary sinus membrane is extremely thin, this procedure is somewhat technically challenging. The membrane may appear fine during surgery but tear during the healing process. If that happens, complications such as sinusitis may occur.

That said, there is no need to be overly concerned. Even if such a problem occurs after surgery, most patients recover well with appropriate treatment.