Internal and external sinus lift: the difference and when each is chosen

What is the sinus and why does it matter for implants?

The maxillary sinus is an air-filled cavity inside the upper jaw, above the roots of the molars and premolars. When these teeth are lost, the bone recedes from below and the sinus expands from above, sometimes leaving too thin a layer of bone to hold an implant.

An implant needs enough bone height to be stable and to carry chewing forces. A sinus lift means gently lifting the membrane lining the sinus and filling the space beneath it with bone graft, so the available bone height increases.

The internal (closed) sinus lift

It is done through the implant site itself. After the site is prepared, the sinus floor is lifted by a few millimetres with special instruments, the graft is placed through the same opening, and in most cases the implant is fixed in the same session.

It is chosen when the deficit is small and the existing bone is enough to hold the implant firmly at placement. It is less invasive, with less swelling afterwards, but it does not suit every case.

The external (open) sinus lift

It is done through a small window opened in the wall of the sinus on the cheek side. The membrane is lifted under direct vision, a larger amount of bone graft is placed, then the window is closed with a membrane and the gum is stitched.

It is chosen when the deficit is large or the remaining bone is very thin. The implant may be placed in the same session if it can be made stable, otherwise it is placed at a later stage after the graft has healed.

How is the technique chosen?

The decision is built on the CBCT scan: the remaining bone height, the shape of the sinus floor, any septa or inflammation inside it, and the thickness of the membrane. On screen the height is measured precisely and it becomes clear whether an internal lift is enough.

• The number of implants needed in the area.
• The health of the sinuses and any chronic sinusitis; an ear, nose and throat opinion is sometimes needed.
• Smoking and general health.
• The patient's wish to reduce the number of stages.

After a sinus lift

In the first days avoid blowing your nose hard, sneezing with your mouth closed, diving and flying where possible; these pressures can affect the lifted membrane. Slight bleeding from the nose or swelling of the cheek can occur, is expected and is followed up.

The area heals in stages, and a follow-up scan confirms bone formation before the implant is placed or loaded. The dentist sets the timing of each step for your case and writes it into the plan.