الفهرس 
INTRODUCTION 1Only 14 pages are availabe for public view
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Abstract
The increasing emphasis on aesthetic expectations in dental treatments has prompted a quest for simplified procedures that benefit both dental practitioners and patients. In this era of technological advancement, various solutions are being explored to meet these demands. CAD-CAM technology was introduced to dentistry for single-unit restorations around thirty years ago, and ongoing technological advancements have enabled the creation of complex multi-unit rehabilitations and implant restorations. The integration of CAD-CAM concepts in dental prosthetics also brought about the emergence of intraoral scanning in the early 1980s.
With the introduction of intraoral scanners, digital impression techniques have undergone significant developments, resulting in more convenient and reliable procedures at various treatment stages. All intraoral scanners are built upon a range of non-contact imaging methods and principles. Utilizing CAD-CAM systems in conjunction with intraoral scanners streamlines planning for a wider range of cases, enhancing patient comfort, communication with laboratories, and treatment efficiency, while also reducing treatment time.
Over the past decade, numerous intraoral scanners with diverse technologies have been developed. The selection of an appropriate scanner system for each case plays a crucial role in the long-term success of the final restoration. The adoption of intraoral scanning devices for digital impressions has gained popularity not only in dental implant cases but also in the fabrication of fixed prostheses on natural tooth abutments. This fully digitalized workflow offers several advantages over traditional impression techniques, including improved patient comfort, time savings, enhanced accuracy, precision, productivity, and access to extraoral digital measurement techniques. Intraoral digital impression acquisition also enables the capture of three-dimensional data encompassing all dento-gingival tissues.
Data acquired through intraoral scanner procedures within digital workflows are subsequently transferred to various software programs to generate three-dimensional digital designs. Some scanners utilize open systems that output data in the Standard Tessellation Language (STL) format, while others operate on closed systems that only export proprietary formats. Output data from open system scanners can be accessed by all design software, while closed systems transmit formatted output data directly to corresponding software for digital design. In cases where data originates from a closed system scanner, a conversion step to the STL format is necessary to enable compatibility with other programs. However, the potential for data loss during these conversion processes can impact the final fit and success of the definitive restoration.
Objective: Evaluate the extent of data loss experienced during the shift from the scanning phase to the design phase, aiming to document the accuracy of different scanning systems. The null hypothesis proposed that the conversions between formats and the transfer of data would have no impact on the precision of diverse scanner systems.
Methods: on a 3D printed model a 49 scans were done using different intraoral scanners (Trios4, Primescan and mediti500) with their corresponding file extension f (PLY, STl, DXD, DCM and Obj) where n=7 in each group. And 49 milled crowns were formed and then all were scanned using InEos X5 an extraoral scanner along with the die.
Results: The correlation between marginal and internal fit is displayed in Table 8 and depicted in Fig 47. A robust and statistically significant positive correlation between marginal and internal fitting was observed (rs = 0.751, p < 0.001)