Objectives To evaluate implant survival and complication rates of narrow-diameter implants (NDIs) supporting fixed restorations under immediate versus early/delayed loading protocols. Data Randomized controlled trials and non-randomized clinical studies reporting implant survival, marginal bone loss (MBL), biological, or prosthetic complications for immediately and early/delayed loaded NDIs were considered. Sources Electronic searches of MEDLINE, Embase, and Scopus were conducted up to January 2026. The study was conducted according to the PRISMA 2020 statement and registered prospectively in PROSPERO (CRD420250654797). Study selection Two reviewers independently performed study selection, data extraction, and risk-of-bias assessment. Nine studies met the inclusion criteria for qualitative synthesis, of which seven provided sufficient data for meta-analysis. Random-effects meta-analyses were conducted when methodologically appropriate, and the certainty of evidence was assessed using the GRADE approach. Conclusions Immediate loading of NDIs supporting fixed restorations may achieve implant survival outcomes comparable to early/delayed loading protocols. Short-term biological, prosthetic, and MBL outcomes appeared similar between loading strategies; however, the certainty of evidence was limited. A higher risk of long-term biological complications with immediate loading was observed, although this finding is based on limited evidence with very low certainty. Clinical significance Immediate loading of NDIs may represent a viable and time-efficient treatment option for fixed restorations in appropriately selected cases. Given the limited certainty of long-term biological outcomes, careful case selection and long-term monitoring remain essential.
Pachiou et al. (Fri,) studied this question.