Immediate Loading of Implants Placed Simultaneously with Sinus Membrane Elevation in the Posterior Atrophic Maxilla: A Two-Year Follow-Up Study on 10 Patients

Background: Clinical studies on immediate loading of implants in the posterior atrophic maxilla are rare. Purpose: The study aims to evaluate immediate loading of implants placed with sinus membrane elevation without additional grafting material for bone augmentation of the maxillary sinus floor. Materials and Methods: The study group comprised of 10 patients in whom a total of 10 maxillary sinus floor augmentations were performed. A total of 21 dental implants (1 to 4) were inserted through the residual bone to protrude into the maxillary sinus under the elevated sinus membrane. The implant site was underprepared to improve primary stability. All the implants were inserted with a torque insertion no less than 20 Ncm. Implants were loaded immediately after surgery with a screw-retained temporary acrylic restoration. Intraoral X-rays were taken at implant insertion, after 6 months loading, and after 1st and 2nd year of loading. Resonance frequency analysis (RFA) was performed at the time of initial placement and after 6 months of functional loading. Results: RFA after implant insertion gave an implant stability quotient (ISQ) level with a range from 62 to 72. All implants remained clinically stable during the follow-up period of 2 years. Radiography demonstrated on average 5.7 +/- 3.4 mm of intrasinus new bone formation after 6 months of implant loading. RFA measurements showed ISQ mean values of 67 (range: 62-72) and 68 (range: 62-71) at placement and after 6 months of loading, respectively. Conclusion: Within the limits of this case series report, it is concluded that maxillary sinus membrane elevation with simultaneous placement and immediate loading of implants without the use of any additional grafting material shows predictable results after 2 years of functional loading. Moreover, evidence of intrasinus bone formation around the implants was found in all patients. Further studies are needed to study the influence of immediate loading on the mineralization of bone forming at dental implant sites.