Sinus Lift Walled Lake, MI Dentist In the rear portion of the upper jaw, the maxillary sinus cavity lies just beyond the jawbone. In many cases, that cavity is so large that there is insufficient bone to allow the secure placement of dental implants. When this occurs, our doctor may recommend a sinus graft. Like bone grafting, a sinus graft involves the surgical application of donor tissue to augment the existing bone structure. Depending on your individual needs, this may be done at the time of implant placement or done in advance and allowed to fully heal before your implants are placed. In either case, your sinus grafting will ensure you have enough strong bone in your upper jaw to anchor your dental implants.