Lateral augmentation of the sinus floor followed by regular implants versus short implants in the vertically deficient posterior maxilla: a systematic review and timewise meta-analysis of randomized studies

The aim of this study was to perform a timewise meta-analysis of randomized clinical trials (RCTs) comparing the outcomes of short implants (& LE;6 mm) versus lateral sinus floor augmentation followed by regular implants (& GE;10 mm) in the deficient posterior maxilla. Eleven RCTs with 1, 3, and 5 years of follow-up were reported in 21 articles. There was no significant difference in the implant loss rate at the patient level after 1 and 3 years between the two groups (risk ratio 0.50, P = 0.17; risk ratio 1.71, P = 0.51). After 5 years, the risk ratio was in favour of regular implants with augmentation and approached significance (3.28, P = 0.06). Excluding the results of two studies on ultrashort implants, the risk ratio for complications was in favour of short implants, but without significance (0.33, P = 0.08). Mean marginal bone loss was significantly lower at 1, 3, and 5 years for the short implants when compared to regular implants with augmentation. The residual osseointegration length of implants was between 3.4 mm and 5.9 mm in the short implants group and between 10.1 mm and 12.5 mm in the regular implants group after 5 years. In conclusion, short implants in the atrophic posterior maxilla demonstrate comparable outcomes to regular implants within the first 5 years. Patients who are fit for surgery should be informed about the risks and benefits of both options.