## 4 Discussion
Although a high-precision, device-native software (Planmeca Romexis 6.2) was used to optimize segmentation, potential inaccuracies introduced during the DICOM-to-STL conversion process--such as those arising from thresholding, inter polation, or smoothing algorithms--cannot be entirely ruled out. While micro-CT was employed for non-destructive evaluation of marginal and internal fit, a voxel-wise or mesh-based comparison between CBCT- and micro-CT-derived STL files was not performed. Furthermore, common CBCT-related artifacts, including beam hardening, scatter, and minor phantom motion, may have affected segmentation quality and dimensional accuracy, particularly around complex inlay geometries. Although the use of standardized phantom models minimized patient-related variability, future studies incorporating quantitative mesh-to-mesh deviation mapping and voxel alignment techniques are recommended to rigorously assess the accuracy of CBCT-based digital models. The micro-CT method was used to evaluate the marginal and internal fit of inlay restorations. This non-destructive method, which allows for repeated measurements, is considered one of the best and recommended methods for evaluating marginal and internal fit [11, 31, 32, 33]. In the fit analysis of restorations, 50 measurements per specimen are recommended to obtain clinically significant information about the marginal gap size, regardless of the systematic or random approaches of the measurement sites. Depending on the required level of precision, at least 20 to 25 measurements per crown are acceptable [34]. In this study, 60 measurements were taken for each inlay restoration. This number is quite substantial in terms of providing clinically significant information. In this study, no adjustments were made to the marginal and internal regions of inlay restorations to ensure standardization. However, it should be noted that in clinical reality, restorations are often adjusted post-milling through chairside modifications to optimize fit. If minor adjustments had been made to the internal surfaces of inlay restorations after milling, as is commonly performed in laboratory and clinical conditions, the marginal gap values could have been reduced. On the other hand, in this study, three different inlay restorations prepared for each preparation sample were not cemented; instead, they were secured to the tooth with paraffin bands for micro-CT analyses. This approach allowed for the control of tooth preparation variables among the groups and eliminated possible cementation errors. Although this non-cemented protocol is widely accepted in micro-CT studies to allow standardized and repeatable measurements, it does not replicate the clinical fit achieved under actual cementation pressure. Additionally, research has reported that the marginal gap is greater in cemented restorations compared to non-cemented restorations [34, 35, 36]. In this study, where the cementation process was not performed, this information should not be overlooked when evaluating the marginal and internal gap values. The use of typodont teeth is one of the limitations of this study. Typodont teeth have been used in many marginal fit studies [11, 14, 19, 37]. [PERSON] et al., in their study on crown preparation, indicated that there were similar results between typodont teeth and extracted natural teeth; they showed that the type of tooth used did not affect the results. However, it should be considered that extracted natural teeth may better reflect real intraoral conditions and could influence scanning accuracy. While this sample size aligns with established protocols in similar in vitro studies, we acknowledge its limitations regarding broad generalizability, and suggest that future research incorporate larger sample sizes with power analysis to confirm these findings. In addition, the quantitative differences between inlays and crowns fabricated with CBCT data were likely influenced by the distinct internal geometry of inlays, which often feature deep boxes and sharp internal angles [9, 18].