Immediate versus early or conventional loading dental implants with fixed prostheses: A systematic review and meta-analysis of randomized controlled clinical trials

Immediate loading of dental implants has gained widespread popularity because of its advantages in shortening treatment duration and improving esthetics and patient acceptance. However, whether immediate loading can achieve clinical outcomes comparable with those of early or conventional delayed loading is still unclear. The purpose of this systematic review and meta-analysis was to compare the efficacy of immediate loading versus early or conventional loading implants in patients rehabilitated with fixed prostheses. Electronic searches of CENTRAL, EMBASE, and MEDLINE were supplemented by manual searches up to October 2018. Only human randomized controlled trials (RCTs) comparing immediate with early or conventional loading dental implants were included. Quality assessment was performed by using the Cochrane Collaboration tool. For the meta-analysis, the dichotomous and continuous variables were pooled and analyzed by using risk ratios (RRs) and weighted mean differences (WMDs), with 95% confidence intervals (95% CIs). The outcomes assessed included survival rate, marginal bone level changes, peri-implant gingival level, probing depth, and implant stability. The subgroup analyses included healing methods, implant time, occlusal contact, number of missing teeth, and tooth position. Thirty-nine trials (49 articles) were included from the initial 763 references evaluated. When compared with conventional loading, with implants regarded as a statistical unit, a statistically significant lower survival rate was observed in the immediate loading dental implant (RR=0.974; 95% CI, 0.954, 0.994; P =.012). Regarding other outcomes, including marginal bone level changes, peri-implant gingival level, probing depth, and implant stability, no statistically significant differences were observed when comparing immediate versus early or conventional loading ( P >.05). Compared with early loading, immediate loading could achieve comparable implant survival rates and marginal bone level changes. Compared with conventional loading, immediate loading was associated with a higher incidence of implant failure.