Accuracy of Metallic-Sleeved Versus Sleeve-Free Surgical Guides in Static Computer-Assisted Implant Surgery: A Systematic Review and Meta-Analysis

Background/Objectives: Metallic sleeves are widely used in static computer-assisted implant surgery (sCAIS), whereas sleeve-free guides may simplify the workflow. This systematic review and meta-analysis compared metallic-sleeved and sleeve-free guides for angular, coronal/platform, and apical deviation. Methods: The protocol was registered in the Open Science Framework and the review followed PRISMA 2020. PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library/CENTRAL, and Google Scholar were searched; reports published in any language were eligible for assessment. Methodological quality and risk of bias were assessed using QUIN for in vitro studies and RoB 2 for the randomized trial. Random-effects meta-analyses were complemented by sensitivity and leave-one-out analyses. Results: Eleven studies were included (10 in vitro and one randomized controlled trial). Nine studies contributed to quantitative synthesis overall. Sleeve-free guides showed lower angular deviation (MD = -0.61°; 95% CI: -1.12 to -0.10; p = 0.019) and apical deviation (MD = -0.27 mm; 95% CI: -0.50 to -0.05; p = 0.017), while no statistically significant difference was detected for coronal/platform deviation (MD = -0.03 mm; 95% CI: -0.16 to 0.11; p = 0.689). Heterogeneity was substantial to high, and the 95% prediction intervals for angular and apical deviation crossed zero, reflecting variability across the evaluated guided systems. Sensitivity and leave-one-out analyses supported the overall direction of the findings. Conclusions: Sleeve-free guides showed modest average advantages in angular and apical deviation, while no statistically significant difference was detected for coronal/platform deviation. Performance depended on guide design, manufacturing accuracy, support, site morphology, and surgical protocol. The SLEEVE Rule was proposed as a structured framework to improve standardisation and comparability in future research. Further well-designed clinical studies are required to determine the clinical relevance of these technical differences.