الفهرس 
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Abstract
Chapter (8) Summary
Provisional restoration has valuable influence on the success of prosthetic treatment. Introduction of digital technology resulted in advances in the dental field. Advances in digital occlusion recording methods seem to achieve a promising means through which dentistry can be made more comfortable, less time-consuming, and of higher quality. Developers of milling systems and 3D printers claim that recent digital technologies promote the accuracy of occlusal reproduction. Yet, literature supporting these claims is minimal.
The current in vitro study aims to digitally analyze the accuracy of occlusion reproduction, in case of both anterior and posterior restorations fabricated by 3 different provisional restoration fabrication workflows (conventional workflow, additive computer-aided workflow, and subtractive computer-aided workflow).
Forty-eight provisional crowns were fabricated in this study. A natural maxillary teeth model of well-defined occlusal anatomy was selected as a control reference model, in this study. The reference model was scanned using Omnicam intraoral scanner, then exported in STL format. This STL file acted as the “Biocopy” used in correlation computer-aided design and acted as the reference model scan (SRM) in the evaluation phase later. To standardize superimposition process, a single model with alveolar dies was fabricated to act as a “reference model” with the unprepared intact dies and act as study model with prepared upper right central (1st scenario) or upper right 1st molar (2nd scenario).
Power analysis recommended sample size of 8 samples per group. Eight crowns anterior and posterior were fabricated with conventional workflow using bis-acryl multifunctional composite.
Eight scans for anterior and for posterior crowns were performed using Omnicam intraoral scanner, scans were performed by coping the “biocopy” reference model scan and cutting the area of the prepared abutment, in order to avoid discrepancy between different scans and reference scan model, as reported by literature. Eight computer-aided designs were performed using correlation mode. Each design was exported as STL file, which was sent to both 5-axes milling machine (K5, vfh) for milling a PMMA crown and DLP 3D printer (NextDent 5100) for 3D printing a provisional crown using micro-filled hybrid bis-acryl-based polymer resin.
All fabricated crowns were seated on their corresponding abutments on the model and scanned using Omnicam intraoral scanner to generate test model scan (STM). These scans were performed using the same reference model scan used in preparation data acquisition and the crown region was cut for standardization for better superimposition accuracy.
Evaluation of the accuracy of occlusal surface reproduction was accomplished by superimposition of each test model scan (STM) on the reference model scan (SRM) on Geomagic Control X 2020 software. Root mean square (RMS) and percentages of surface area within, above and below tolerance range (±20µm).
Results of the current study rejected the null hypothesis, as significant influence of fabrication workflow and its interaction with the anatomical location of fabricated crown on the accuracy of occlusal surface reproduction.