Optimizing Digital Impressions: A Review of Factors Affecting Intraoral Scanner Accuracy

Background: Digital intraoral scanners (IOSs) represent one of the key tools in contemporary digital dentistry and are widely applied in prosthodontics, orthodontics, implantology, and treatment monitoring. The aim of this study was to critically analyze the factors affecting the accuracy of intraoral scanning and to evaluate their clinical significance. Methods: This study was designed as a narrative literature review conducted using a structured literature search. The analysis was based on publications retrieved from the PubMed and ScienceDirect databases and published between 2016 and 2026 using keywords related to intraoral scanners, digital impressions, trueness, precision, scanning strategy, operator experience, scanner type, restorative materials, and clinical conditions. Results: Twenty publications selected according to the review scope and eligibility criteria were included. Based on the analysis, four major groups of factors influencing IOS accuracy were identified: scanning strategy, operator experience, scanner type and restorative material, and clinical/environmental conditions. The available evidence most consistently associated scan quality with the scanner type and the applied scanning strategy, although the effectiveness of individual protocols depended on the specific IOS system used. The influence of operator experience remained inconclusive and appeared to be less significant in modern devices equipped with advanced image reconstruction algorithms. Clinical factors such as lighting conditions, arch morphology, subgingival preparation margins, maneuverability restrictions, and material-related optical properties also played an important role, whereas humidity and moisture control should be interpreted as possible clinical confounders rather than experimentally verified independent factors in the included primary studies. Conclusions: The findings indicate that intraoral scanning accuracy is a multifactorial phenomenon requiring individualized adaptation of the scanning procedure to clinical conditions and the type of IOS system used. Because the included evidence was heterogeneous and did not allow for formal ranking of effect magnitude, conclusions regarding the relative importance of individual factors should be interpreted with caution.