Influence of Scan Body Exposure Height on Digital Impression Accuracy in Maxillary Anterior Implants: A Pilot Study

Purpose: This study evaluated the influence of the supragingival scan body (SB) exposure height on the accuracy of intraoral digital impressions at maxillary anterior implant sites.Materials and Methods: Digital impression datasets from two maxillary anterior implant sites were retrospectively analyzed.A Short SB scan was performed during the provisional restoration stage, whereas a Long SB scan was performed during the definitive restoration stage.A stone cast was fabricated from a provisional stage open-tray polyvinyl siloxane impression, and the same cast was digitized with each physical SB seated to generate condition-specific reference datasets.The iterative closest point (ICP) registration root mean square (RMS) error was recorded, and the linear deviation (LD) and angular deviation (AD) were obtained using Random Sample Consensus (RANSAC)-based cylinder fitting.Statistical analyses were not performed due to the single-patient design of the study.Results: The mean supragingival SB exposure heights were 6.39 mm and 2.73 mm for the Long SB and Short SB conditions, respectively.The Long SB condition demonstrated lower ICP registration RMS error (29.8 µm) than the Short SB condition (70.4 µm).Mean LD values were 1.17 and 1.35 mm, and mean AD values were 0.85° and 3.68° for the Long SB and Short SB conditions, respectively. Conclusion:In this retrospective single-patient pilot study, the dataset with reduced supragingival SB exposure height showed greater AD and higher ICP registration RMS errors at the maxillary anterior implant sites.Although no causal relationship can be established from these findings, the supragingival SB exposure height may warrant further investigation in relation to digital implant impression accuracy.