Long-term implant survival in the grafted maxillary sinus: a systematic review

The predictability of maxillary sinus augmentation has been extensively reported. Procedural outcomes, most often measured as implant survival rates, have customarily used inclusion criteria that included a minimum 1-year loading time. The inclusion criteria of this review extended the minimum postloading evaluation to 3 years to determine if the previously reported short-term survival rates are maintained. An electronic search of the literature was performed and retrieved articles were screened using specific inclusion criteria, paramount of which was a minimum of 3 years of follow-up. The search revealed 18 articles for the lateral window approach (6,500 implants in 2,149 patients) and 7 for the transalveolar approach (1,257 implants in 704 patients). Overall, implant survival after a minimum of 3 years loading was 93.7% and 97.2% for the lateral window and transalveolar approaches, respectively. Of importance is the fact that 80% of failures occurred within the first year and 93.1% of the failures occurred within 3 years. The risk of implant failure after 3 years can now be directly calculated as the overall risk of failure after 3 years (6.3%) × the incidence of late failures (6.9%), thus equaling 0.43%. This review discredits the theory that studies of a lower level of evidence report inflated results when compared with prospective randomized controlled clinical trials.