Maxillary Sinus Floor Augmentation by Two-Stage Sinus Membrane Elevation Using a Titanium Bone Fixation Device and Dental Implants in a Severely Atrophic Posterior Maxilla: A Case-Series Study
Patients were selected from the outpatient clinic of the Oral and Maxillofacial surgery Department, Saitama Medical Center, Saitama Medical University between March 2008 and July 2012. All patients were fully informed about the present protocol and provided written consent for participation. The study protocol was approved by the institutional ethics committee.
Maxillary sinus augmentation was implemented by two-stage sinus membrane elevation without grafting materials. First, the sinus membrane was elevated by the lateral approach according to a sinus lifting technique using a titanium bone fixation device as described previously.2 Six months after the first surgery, the second sinus membrane elevation was planned in combination with implant placement. After removal of the bone fixation device, second sinus membrane elevation was performed by a lateral approach similar to the first sinus lift or by a crestal approach using the osteotome technique, and an implant (Nobel Replace Tapered GroovyTM, TiUniteTM; Nobel Biocare AB, Göteborg, Sweden) was inserted through the maxillary ridge into the space created under the elevated sinus membrane. Four to six months after implant insertion, a screw-retained restoration was fabricated and loaded. Pre- and postoperative alveolar crest heights were evaluated using panoramic radiograph and CT reformatted using Simplant ProTM software (Materialise Dental NV, Leuven, Belgium).
The surgical technique was performed in 10 maxillary sinuses of 7 patients (2 men, 5 women; mean age, 59.1 years). At the second sinus membrane elevation, a total of 23 implants of lengths 8-13 mm were placed in the alveolar crest with sufficient initial stability. During the follow-up after first and second surgeries, wound healing was uneventful and no intra-sinus problems were reported. One of the 23 implants was lost during abutment connection, and it was simultaneously replaced with a wide platform implant. The implant survival rate was 95.7%. Radiographic examination revealed that the mean preoperative residual bone height was 2.8 mm (range, 0.8-6.3 mm). Six months after the first sinus lift, medial invasion of new dense bone and various-sized exposure of titanium screws into the sinus cavity were detected. Six months after the second sinus lift in combination with implant placement, additional medial invasion of new dense bone was observed in vertical direction in the space under the elevated sinus membrane and the new sinus floor was observed proximal to the implant apex. Mean postoperative alveolar bone height after the first sinus lift was 6.4 mm (range, 2.5-9.4 mm) and second sinus lift was 8.9 mm (range, 5.6-14.5 mm).
Membrane elevation maintained for a certain period can generate new bone in the secluded space under the elevated sinus membrane, and repeated elevation of the sinus membrane may increase the bone volume in the sinus.