## 1 Introduction  
The marginal and internal fit of fixed prosthetic restorations applied in dentistry significantly affects the success and lifespan of fixed prosthetic restorations. In prostheses where successful marginal and internal fit of the crown cannot be achieved, plaque accumulation may lead to microleakage, resulting in issues such as caries, pulpal inflammation, periodontal disease, and a decrease in the retention of the restoration [1, 2, 3, 4]. For this reason, obtaining an accurate impression that clearly reveals the marginal and internal fit is the first step in producing a successful prosthesis. However, traditional intraoral impressionscan be challenging for both clinicians and patients due to factors such as gag reflex, lack of comfort, or the risk of soft tissue damage. Additionally, environmental conditions like temperature and humidity changes during the transfer of the impression to the laboratory may cause dimensional changes in the impression material. These factors can negatively impact the marginal and internal fit of the prosthesis [5; 6; 7]. With the advancement of digital dentistry, computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies have replaced traditional impressions, which have some disadvantages [8]. This process involves scanning the prepared tooth surface and then designing the crowns. This workflow consists of sequential stages including data acquisition, design, and manufacturing. In the data acquisition phase, digital impressions are obtained either directly using intraoral scanners or indirectly via model scanners, resulting in the creation of a 3D model in standard tessellation language (STL) format. During the design phase, specialized software is used to digitally design the restoration. In the final stage, the designed restoration is fabricated using a CAM device. CAD/CAM technology is increasingly used in dental prosthetic restorations because it eliminates the drawbacks of traditional impression methods. It reduces laboratory time and material costs while increasing productivity. With the development of different manufacturing systems, a wide range of dental materials, such as ceramics, acrylic resins, waxes, and metal alloys, are now available in prefabricated block form for prosthetic restorations. In this context, the acquisition of digital data and models has become of great importance [9; 10]. These models can be obtained directly with intraoral scanners or indirectly with laboratory scanners. The indirect method begins with a traditional impression, followed by the creation of a model, which is then typically digitized using three-dimensional (3D) laboratory scanners. As a third option, cone-beam computed tomography (CBCT) images can be converted into the STL using CAD software (Cerec CAD System, Sirona Dental Systems GmbH, Bensheim, Germany) and used in the production of prosthetic restorations without the need for traditional impression-taking [10; 11; 12; 13]. Many studies have been conducted on the marginal fit of crowns produced using CAD-CAM technology and those obtained by traditional methods. The evaluation of marginal and internal fit is of critical importance. Furthermore, various factors such as scanning, design, and milling processes can affect the accuracy of the fit of restorations. The success of the restoration is directly related to the marginal and internal fit of the crown, and ensuring this integrity is determined by fundamental principles [13; 14; 15; 16; 17]. An vitro alternative that is widely used to evaluate the marginal and internal fit success of crowns is microcomputed tomography (MCT). MCT is a non-destructive digital method for the 2D or 3D radiographic analysis of internal and marginal gaps in restorations. This method utilizes a cone-beam X-ray source and specialized reconstruction software to generate cross-sectional images for a comprehensive assessment of marginal and internal gaps [18]. Although no clear definition of acceptable marginal fit has been made, [PERSON] et al.