Flapless, CBCT-guided osteotome sinus floor elevation with simultaneous implant installation. I: radiographic examination and surgical technique. A prospective 1-year follow-up

Background: Survival rates of implants placed in transalveolar sinus floor augmentation sites are comparable with those placed in non-augmented sites. Flapless implant surgery can minimize postoperative morbidity, alveolar bone resorption and crestal bone loss. The use of cone beam computerized tomography (CBCT) provides 3D presentations with reduced dose exposure. Objectives: To evaluate a flapless, CBCT-guided transalveolar sinus floor elevation technique with simultaneous implant installation. Material and methods: Fourteen consecutive patients in need of maxillary sinus floor augmentation were enrolled in this study. Preoperative CBCT with a titanium screwpost as an indicator at the intended implant position was used to visually guide the flapless surgical procedure. Twenty one implants all with a length of 10mm and a diameter of 4.1 and 4.8mm were inserted and followed clinically and with CBCT for 3, 6 and 12 months postoperatively. Intraoral radiographs were taken for comparison. All patients were provided with permanent prosthetic constructions 8-12 weeks after implant surgery. Results: Ten (47.6%) implants were inserted in residual bone of 2.6-4.9mm and 11 (52.3%) implants were inserted in residual bone of 5-8.9mm. No implants were lost after surgery and follow-up. There was no marginal bone loss during the follow-up verified by CBCT. The implants penetrated on average 4.4mm (SD 2.1mm) into the sinus cavity and the mean bone gain was 3mm (SD 2.1mm). Conclusion: Flapless transalveolar sinus lift procedures visually guided by preoperative CBCT can successfully be used to enable placement, successful healing and loading of one to three implants in residual bone height of 2.6-8.9mm. There was no marginal bone loss during the 3-12 months follow-up.