[Minimally invasive sinus lift. Limits and possibilities in the atrophic maxilla].

The minimal invasive sinus lift is a procedure done by osteotome technique via a crestal approach in contrast to the sinus elevation via lateral osteotomy to achieve adequate bone-height for setting of implants. The purpose of this anatomical and clinical study was to evaluate by endoscopic control if the minimal sinus lift is practicable by a residual bone height of less than 8 mm without mucosal damage. An endoscopic controlled sinus lift was done on 10 fresh cadavers. The original bone height was 3-6 mm in the lateral maxilla. The sinus mucosa was elevated by an osteotome at least up to 10 mm. A sinus augmentation was performed with a bone substitute material (Algipore) over the implant bed. There was no tear visible on endoscopic control. Finally, the maxilla was removed and the mucosa inspected. No laceration of the mucosa was found in any case. The clinical study included 7 patients. 5 Patients had bone condensation, augmentation of bone and implantation of 13 mm implants in a one stage procedure. The originally bone height was between 6-8 mm in all patients. One of the five patients did show a small perforation of the mucosa during mucosal elevation at one implant-bed. The implant was inserted and an endoscopic control after 6 weeks showed regular mucosa. 2 patients received augmentation only at a primary bone height of only 3-5 mm. A post-operative CT-scan showed that the bone height was augmented to a total height of 13-16 mm. As a result of our study a sufficient bone height can be achieved by the minimal invasive sinus lift procedure. The advantage of this crestal approach is the protection of the intraosseous vessels in the maxilla and less postoperative morbidity. As a disadvantage, the insertion of bone material limited only to the area surrounding the implant bed, might be discussed.