Current State of Evidence for Implant Placement and Loading in Partially Edentulous Patients: A Systematic Review

To systematically review the updated evidence for the clinical outcome of fixed implant prostheses treated with different combinations of implant placement and loading protocols in partially edentulous patients.

An electronic search was performed in Medline, Embase, and Central to identify studies of implants subjected to immediate placement + immediate restoration/loading (Type 1A), immediate placement + early loading (Type 1B), immediate placement + conventional loading (Type 1C), early placement + immediate restoration/loading (Type 2-3A), early placement + early loading (Type 2-3B), early placement + conventional loading (Type 2-3C), late placement + immediate restoration/loading (Type 4A), late placement + early loading (Type 4B), late placement + conventional loading (Type 4C) with implant-supported fixed dental prostheses (IFDPs) in partially edentulous patients. A cumulative survival rate for each type of the implant placement and loading protocols was weighted by the duration of follow-up and number of implants.

From 11 427 records, 140 studies (42 RCTs; 98 CCTs/cohort studies) encompassing 10 456 implants met the criteria. Weighted cumulative survival rates for each protocol were: 98.0% (Type 1A), 91.6% (Type 1B), 95.0% (Type 1C), 97.8% (Type 2-3A), 100% (Type 2-3B), 94.0% (Type 2-3C), 97.2% (Type 4A), 97.9% (Type 4B), 97.5% (Type 4C). Protocols 1A, 1C, 2-3C, 4A, 4B, and 4C satisfy scientific and/or clinical validation thresholds, whereas 1B and 2-3B remain insufficiently documented despite high numeric survival.

In immediate placement, Type 1C shows strong survival rates. It is considered scientifically and clinically validated, while Type 1A also meets the criteria for a scientifically and clinically validated protocol with high survival rates. Meanwhile, Type 1B continues to show lower and more variable survival rates-being clinically documented-underscoring the need for careful case selection. Regarding early placement, Type 2-3C is recognized as a scientifically and clinically validated protocol. Type 2-3A, which was previously underreported, now demonstrates similarly validated survival rates that expand the evidence for early implant placement with immediate loading. Although Type 2-3B is clinically documented, it still lacks sufficient evidence. All late implant placement protocols are considered scientifically and clinically validated: Type 4C offers high survival with long-term predictability, while Type 4A and Type 4B maintain stable survival rates backed by well-established evidence.