Loading Protocols for Single-Implant Crowns: A Systematic Review and Meta-Analysis

Purpose: To test whether or not immediate loading of single-implant crowns renders different results from early and conventional loading with respect to implant survival, marginal bone loss, stability of peri-implant soft tissue, esthetics, and patient satisfaction. Materials and Methods: An electronic search of Medline and Embase databases including studies published prior to August 1, 2012, was performed and complemented by a manual search. Randomized controlled trials (RCTs) comparing different loading protocols of singleimplant crowns with a follow-up after restoration of at least 1 year were included. A meta-analysis yielded odds ratios (OR) and standardized mean differences (SMD) together with the corresponding 95% confidence intervals (95% CI). Results: The search provided 10 RCTs comparing immediate and conventional loading and 1 RCT comparing immediate and early loading. When assessing the implant survival at 1 year of loading, the meta-analysis of 10 studies found no significant differences between immediate and conventional loading (OR = 0.75; 95% CI: 0.32 to 1.76). The total difference of marginal bone loss during the first year of function between immediate and conventional loading protocols in 7 RCTs did not reach statistical significance (SMD = -0.05 mm; 95% CI: -0.41 to 0.31 mm). There were no significant differences between immediate and conventional loading regarding implant survival and marginal bone loss at 2, 3, and 5 years of loading. Three RCTs comparing the change of papilla level between immediate and conventional loading identified no significant differences. One study investigated the recession of the buccal mucosa after implant placement and found significantly inferior soft tissue loss for immediate loading as compared to conventional loading. Two RCTs investigated the recession of the buccal mucosa after insertion of the definitive crown and found no differences between immediate and conventional loading. The esthetics and the patient satisfaction were assessed in one and two RCTs, respectively. There were no significant differences between immediate and conventional loading. Conclusions: Immediately and conventionally loaded single-implant crowns are equally successful regarding implant survival and marginal bone loss. This conclusion is primarily derived from studies evaluating implants inserted with a torque ≥ 20 to 45 Ncm or an implant stability quotient (ISQ) ≥ 60 to 65 and with no need for simultaneous bone augmentation. Immediately and conventionally loaded implants do not appear to differently affect the papilla height during the first year of loading. Due to the heterogeneity of the time point of baseline measurements and contradictory findings in the studies, it is difficult to draw clear conclusions regarding the recession of the buccal mucosa. With respect to the assessment of esthetic outcomes and patient satisfaction, the data available remain inconclusive. Keywords: bone, crowns, dental implants, early, esthetics, function, immediate, loading, meta-analysis, papilla, restoration, satisfaction, soft tissue, survival, systematic review