Implants in the upper back jaw frequently require an additional procedure before they can be placed. The reason is anatomical rather than a reflection of any patient's condition.
The maxillary sinus limits available height
Above the upper molars and premolars sits an air-filled cavity within the cheekbone, lined by a thin membrane and separated from the mouth by a layer of bone.
That layer can be quite thin even in a healthy mouth, leaving less vertical bone than an implant of standard length requires.
Since an implant must be fully surrounded by bone, the sinus floor sets a hard ceiling on what can be placed without modification.
Losing a tooth makes the gap smaller
When an upper back tooth is removed, the ridge below resorbs from above while the sinus tends to expand downward into the space left behind.
The two processes work toward each other, so the interval between them narrows over the years following an extraction.
A site that would have accepted an implant readily soon after the tooth was lost may need grafting once considerable time has passed.
The membrane is lifted rather than removed
The procedure involves carefully separating the sinus lining from the bone beneath it and raising it, creating a space between the lining and the original floor.
Graft material is placed into that space, and over the following months the body converts it into bone that extends the ridge upward.
The membrane itself stays intact and continues to line the sinus. Keeping it unperforated is the technical challenge of the procedure.
Two approaches suit different starting heights
Where a moderate amount of bone already exists, the floor can be raised through the implant site itself, gaining a limited increase at the time of placement.
Where very little bone remains, access is made through a small window in the side wall of the jaw, allowing a larger and more controlled graft.
Choosing between them depends on measurements from three-dimensional imaging, and the second approach usually means waiting before the implant is placed.
Recovery and what should be reported
Swelling and some nasal congestion on the treated side are common in the days afterward, and instructions typically restrict nose blowing to avoid pressure on the graft.
Existing sinus disease, allergies and smoking all affect suitability and healing, which is why medical history forms part of the assessment.
Persistent discharge, worsening pain or a foul taste are not expected and should be reported to the treating clinician promptly rather than waited out.