Impact of prefabricated aids and auxiliary devices for scan bodies on the accuracy of intraoral scanning for full‐arch implant impressions: A systematic review

PURPOSE: To evaluate, in human clinical studies, the effect of prefabricated aids/auxiliary devices for implant scan bodies (ISBs) on the accuracy (trueness and precision) of full-arch intraoral scanning (IOS). METHODS: A PRISMA-guided search (PubMed, Embase, and Scopus; registered in PROSPERO (CRD420251027002)) identified comparative clinical studies of edentulous complete arches assessing IOS with prefabricated auxiliary devices versus IOS alone, stereophotogrammetry (SPG), and/or conventional impressions. Outcomes were linear/angle deviations and related 3D metrics. Risk of bias was appraised using Joanna Briggs Institute (JBI) tools; due to heterogeneity, a narrative synthesis was performed. RESULTS: Six clinical studies (2022-2025) involving 73 patients and 366 implants met the inclusion criteria (five quasi-experimental, one cross-sectional). Devices included tooth-modified ISBs, one-piece connectors, multi-component prefabricated auxiliary devices, and bar-type splints. Across studies, prefabricated auxiliary devices often reduced linear (distance) deviation and improved ISB recognition, with scanner-/device-dependent effects; findings for angular deviation and precision were smaller or inconsistent. In head-to-head comparisons, SPG frequently showed higher complete-arch accuracy on several metrics, whereas IOS (± aids) generally required less chairside time and fewer steps. Overall risk of bias was low-moderate for quasi-experimental studies and moderate-high for the cross-sectional study. CONCLUSION: Based on low- to moderate-certainty clinical evidence, prefabricated auxiliary devices for ISBs may enhance complete-arch IOS accuracy, primarily by reducing linear deviation, but benefits are system-specific and not uniform for angular deviation or precision. They should be considered adjuncts to rigorous scanning protocols. Evidence for reduced linear deviation is clinical, whereas other interpretations are partly extrapolated. Standardized, adequately powered clinical trials with uniform accuracy metrics and clinically relevant endpoints are needed.