Internal (closed) sinus lift

In an internal (closed, crestal) sinus lift, the sinus floor is raised by a few millimetres through the site where the implant will be placed, using instruments called osteotomes. The working area is more limited than in the open (lateral-window) approach, and the implant is often placed in the same session.

Whether it is suitable is decided after the remaining bone height has been measured on a 3D scan (CBCT). In the literature the closed approach is generally recommended where bone height is about 4–5 mm or more. In a multicentre study, implant survival was 96% or higher with bone height of 5 mm or more and 85.7% with 4 mm or less (Rosen et al. 1999). A more recent meta-analysis reported that the technique can be a reliable option even with limited bone height (Guo et al. 2020). If bone is very limited, the open approach, short implants or other options are discussed together.

Small tears of the sinus membrane can occur; most can be managed during the procedure, and if necessary the procedure is postponed or the method changed. With techniques that use tapping, a short-lived dizziness triggered by head movements (benign paroxysmal positional vertigo) has rarely been reported. No method removes risk entirely.

In the first days after the procedure, mild swelling, tenderness and a little blood-tinged discharge from the nose can occur. To avoid raising pressure in the sinus, patients are generally advised for the first 1–2 weeks not to blow their nose, to sneeze with the mouth open, not to drink through a straw and not to smoke, and for about 2 weeks to avoid flying, diving, strenuous exercise and wind instruments. The exact periods are set by the clinician for each patient; medicines are taken only as the clinician advises.

Patients should contact their clinician if pain or swelling increases, if they have a fever, a foul-smelling or pus-like discharge from the nose or mouth, air passing between mouth and nose, or complaints lasting more than three weeks. An expert consensus report recommends follow-up visits weekly in the first month and monthly for the following three months (Testori et al. 2012).

Rouzbeh Fazeli's specialty thesis at Ege University compared two instruments used to raise the sinus floor in the closed technique, the magnetic mallet and the hand mallet, in a randomised controlled trial. Patients with remaining bone height of 4 mm or less were included, and all received short implants; what was compared was the type of mallet, not the type of implant. The study was presented as a poster abstract at the EAO 2019 congress in Lisbon.