## 2 Materials and Methods  
The sample size was determined based on previous studies evaluating marginal and internal fit using micro-CT, which typically employed 8 to 12 specimens per group to yield statistically meaningful results due to the high spatial resolution and reproducibility of the method [11; 14; 19]. Accordingly, a total of 11 mandibular molar typodonts (with enamel, dentin, and pulp layers) (Frasaco, Tettnang, Germany) were used for inlay cavity preparation. Mandibular molars were selected due to their wide occlusal surfaces and complex morphology, which make them ideal for assessing marginal and internal fit in inlay restorations. All typodont teeth were of the same brand and model to ensure standardization in terms of size and anatomy. A special bur set was used for mesio-oclusal inlay cavity preparation (Intensiv, Niigata, Japan). The following geometrical parameters for the inlay cavity were kept: 3 mm isthmus width, 1.5 mm axial depth, 2.5 mm occlusal depth, 1 mm rounded shoulder margin in the axio-gingival angle, and a 6-10-degree tapered angle. All inlay cavities were performed by the same operator using a phantom model to ensure standardization of the preparations. The inlay preparation was scanned with an intraoral scanner (CEREC Omnicam system, Sirona Dental Systems GmbH, Bensheim, Germany), a model scanner (inEOS X5, Sirona Dental Systems GmbH, Bensheim, Germany), and CBCT (Planneca Promax 3D Max Machine, Helsinki, Finland). CBCT scans were performed 0.075 mm voxel size. In order to standardize the imaging technique, all scans were taken at 90 kVp, 12 mA, and 50 mm \(\times\) 40 mm FOV size. Prior to the main study, all scanning devices were calibrated and checked according to the manufacturers' guidelines. The intraoral scanner (CEREC Omnicam; Sirona Dental Systems GmbH, Bensheim, Germany), model scanner (inEOS X5; Sirona Dental Systems GmbH, Bensheim, Germany), and CBCT unit (Planneca Promax 3D Max; Planneca Oy, Helsinki, Finland) underwent routine quality control, including internal calibration and software-based diagnostic checks. In addition, test scans were performed to ensure consistent output and proper device performance before data collection. The DICOM data acquired from CBCT were converted to STL format through a specialized 3D mesh processing software system (Planneca Romerxis version 6.2, Helsinki, Finland), which can be used in most CAD software (Planneca Romexis version 6.2, Planmeca Oy, Helsinki, Finland; available at: [[https://www.planmeca.com/dental-software/romexis-viewer/](https://www.planmeca.com/dental-software/romexis-viewer/)]([https://www.planmeca.com/dental-software/romexis-viewer/](https://www.planmeca.com/dental-software/romexis-viewer/)), [[https://www.planmeca.com/dental-software/downloads/](https://www.planmeca.com/dental-software/downloads/)]([https://www.planmeca.com/dental-software/downloads/](https://www.planmeca.com/dental-software/downloads/)), accessed on 20 February 2024). The 3D STL images obtained from the intraoral scanner, laboratory scanner, and CBCT scans were transferred to a CAD software (Cerecc CAD System, Sirona Dental Systems GmbH, Bensheim, Germany), and CBCT (Planneca Promax 3D Max Machine, Helsinki, Finland). CBCT scans were performed 0.075 mm voxel size. In order to standardize the imaging technique, all scans were taken at 90 kVp, 12 mA, and 50 mm \(\times\) 40 mm FOV size. Prior to the main study, all scanning devices were calibrated and checked according to the manufacturers' guidelines. The intraoral scanner (CEREC Omnicam; Sirona Dental Systems GmbH, Bensheim, Germany), model scanner (inEOS X5; Sirona Dental Systems GmbH, Bensheim, Germany), and CBCT unit (Planneca Promax 3D Max; Planneca Oy, Helsinki, Finland) underwent routine quality control, including internal calibration and software-based diagnostic checks. In addition, test scans were performed to ensure consistent output and proper device performance before data collection.