Clinical efficacy of immediate implant loading protocols compared to conventional loading depending on the type of the restoration: a systematic review

Background and objectives: Immediate loading has become a predictable option to restore all clinical situations. The aim of this systematic review was to assess whether immediate loading protocols achieve comparable clinical outcomes when compared to conventional loading protocols depending on the type of prosthetic restoration. Methods: A protocol was developed aimed to answer the following focused question: What are the effects of immediate implant loading protocols compared to conventional implant loading, in terms of implant failure, marginal bone levels, and biological and mechanical complications based on the type of restoration? The next subanalysis were performed as follows: the extent, type, and material of the restoration and the type of occlusal contact in function. This systematic review only included randomized controlled trials (RCTs) with a follow-up of at least 6 months after implant loading. Results: Thirty-seven final papers were included. The results from the meta-analyses have shown that the immediately loading implants demonstrated a statistically significant higher risk of implant failure [RR = 1.92; 95% CI (1.04; 3.54); P = 0.036], a statistically significant lower bone loss [WMD = 0.046; 95% CI (0.043; 0.049); P = 0.000] and a smaller increase in ISQ values [WMD = 1.096; 95% CI (1.615; 0.577); P < 0.001, although both groups attained high survival rates (98.2% in the test and 99.6% in the control). Single teeth implants were greater risk of failure, when compared to immediately loaded full arch restorations (RR = 2 vs. 0.9), so as the occlusal pattern when compared to non-occlusal (RR = 1.9 vs. 1.4). Conclusions: Immediate loading may impose a greater risk for implant failure when compared to conventional loading, although the survival rates were high for both groups.