ILLUSTRATIVE DATA VERSION — NOT FOR SUBMISSION Accuracy and Passive Fit of Digital versus Conventional Impression Techniques for Full-Arch Implant-Supported Prostheses: A Comparative In Vitro Study

Abstract

Background: The passive fit of a definitive framework is a critical determinant of the long-term mechanical stability and biological health of a full-arch implant-supported prosthesis. Discrepancies at the implant–abutment or framework interface, even at the micron level, can generate residual stress within the prosthetic components and surrounding bone, potentially contributing to screw loosening, framework fracture, or marginal bone loss. As digital workflows increasingly replace conventional impression techniques in implant prosthodontics, it is important to establish whether intraoral scanning can reproducibly match or exceed the accuracy achieved with conventional splinted impressions across multiple-implant configurations. Materials and Methods: A standardized reference model incorporating six parallel implant analogues was used to simulate a full-arch edentulous arch. We performed ten illustrative repetitions for each impression technique (digital and conventional). We captured digital impressions with an intraoral scanner, while conventional impressions used a splinted open-tray technique with a rigid impression material. Result datasets/casts were superimposed onto the reference model to calculate root-mean-square (RMS) deviation, linear deviation, and angular deviation at each implant position. Passive fit was assessed via marginal microgap measurement at the framework–abutment interface using a one-screw test protocol. Results: In this illustrative dataset, digital impressions demonstrated lower RMS, linear, and angular deviations relative to the reference model compared with conventional impressions, suggesting a trend towards higher overall accuracy for the digital workflow. Conversely, the conventional impression group showed a small, statistically non-significant advantage in marginal microgap values, indicating a marginally tighter passive fit at the framework interface. No consistent pattern favouring one technique across all outcome measures was observed. Conclusion: The reported numerical results are illustrative only, intended to demonstrate the requested structured-abstract reporting format, and must not be interpreted as findings from an actual study.