الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Dental study models are essential for implant treatment planning, for fixed and removable prosthesis and for orthodontic diagnosis, planning, and treatment evaluations. Digital dental workflow has invaded modern dental treatment and digital modelling has prompted ongoing research. Many methods are available for digital model production and their accuracy has to be assessed.
The present study aimed to assess and compare the accuracy of three- dimensional digital dental models obtained from four different sources: CBCT scanning of the impressions and the corresponding casts besides desktop scanning of the same impressions and casts and comparing them to the gold standard one which is the conventional stone cast.
The study was conducted on thirty-six patients by making bimaxillary silicone-based impressions. Four linear measurements (anteroposterior, inter-canine, inter-molar and vertical dimensions) were measured in all virtual models and compared with the calliper measurements of the stone cast. Additionally, STereoLithography (STL) files from the four virtual model techniques were paired and registered by using a best-fit matching in a 3D modelling software. Mean deviations between the virtual meshes were measured by the software and colour maps were checked for qualitative assessment.
Study results analysis revealed significant differences in some linear measurements but all were within a clinically accepted range. Virtual models
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obtained from laser scanning of the impressions were found to have the least mean differences from the calliper measurements ranging from (-0.24 to 0.01 mm), whereas laser scanning of the casts showed mean differences ranging from (-0.21 to
0.01 mm). CBCT scanning of the casts revealed intermediate differences (0.17 to -
0.02 mm), while CBCT scanning of the impressions mean differences ranged from (0.16 to -0.04 mm). Also, 3D deviation analysis showed comparable differences between the groups.
The current study concluded that scanning the impression with a desktop scanner provided the highest accuracy in followed by scanning of the stone casts. CBCT scanning of the impressions and stone casts provided acceptable results but with decreased surface texture of the 3D mesh. All techniques can be used in clinical practice providing the use of highly accurate machines.