Saudi Cultural Missions Theses & Dissertations
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Item Restricted Evaluating an Innovative Artifact-Resistant Marker-Based Registration Method for CBCT-Guided Implant Planning(University of Connecticut, 2024) Buholayka, Maryam; Tadinada, Aditya; Lurie, Alan G; Dhingra, Ajay KObjective: Radiographic guides are instrumental for the digital design of surgical guides in image-guided dental implantology. These radiographic guides are used as part of the digital-workflow to couple dental anatomy and occlusion with the bony anatomy of the implant site, which is obtained using CBCT. A key step of the coupling process is called registration, which can be achieved using various methods. Unfortunately, all these methods present technical shortcomings that are specially exacerbated when CBCT images present metal or beam-hardening artifacts. The objective of this research was to evaluate a novel, artifact-resistant registration method using the principles of 2D orthogonal-imaging with fiducial markers for image-guided implant planning. Study Design: This in-vitro study included five scenarios with varying levels of image artifacts (absent, minimal, mild, moderate, and severe); where a radiographic guide was registered with (1) a widely used conventional registration method, and (2) the proposed marker-based orthogonal-imaging registration method. A paired student’s T test and one-way ANOVA were used for statistical analysis. Three evaluators (OMFR residents) performed both registration methods in order to evaluate inter-operator reliability using ICC scores. Results: Both the surface-based and proposed marker-based registration methods presented high reliability, with ICC scores of 0.88 and 0.99 respectively, and consistent results at all artifact levels. The accuracy of the proposed orthogonal-imaging marker-based method (0.00018 mm) was significantly better (p > 0.0001) compared to the surface-based registration method (0.175 mm). Conclusion: The use of orthogonal-imaging for radiographic guide registration in dental implantology has the potential to reduce registration error by an order of magnitude. This increased accuracy has the potential to improve implant placement; especially in complex cases. Furthermore, this novel method should be easy to implement clinically by utilizing the projection (i.e., basis) images that are routinely acquired for CBCT imaging.20 0Item Restricted Accuracy Assessment of 3D Printed Casts Using Zirconia Fixed Implant prosthesis: A Comparative Study in the Anterior Maxilla(Saudi Digital Library, 2021-06-23) Abdeen, Layal; Papaspyridakos, Panagiotis; Chen, Yo-wei; Kostagianni, Aikaterini; Finkelman, Matthew; Papathanasiou, Aikaterini; Papaspyridakos, PanagiotisObjective: The purpose of the present in-vitro study is to compare the accuracy of 3D printed casts generated from digital implant impressions with one intra-oral scanner (IOS) (Trios 3, 3Shape), from 4 3D printers, with the 3D accuracy of stone casts made by conventional implant impressions, in a partially edentulous anterior maxilla with two implants. Material and Methods: A maxillary cast with a partially edentulous anterior area was fabricated with the placement of two internal connection implants (Regular CrossFit, Straumann®, Switzerland). Stone casts (n=10) that served as a control were fabricated using the splinted open-tray impression technique. A digital impression was taken using a white light IOS (TRIOS, 3Shape), and a Standard Tessellation Language (STL) file was obtained. Four 3D printers were used to print the casts (n=10 from each 3D printer): a Straumann® P30+ (Straumann®, Switzerland) and a Varseo S (Varseo 3D printing system, BEGO®, Germany), which used digital light processing (DLP) technology; a Form 3b+ (Formlabs®, Somerville, MA, USA), which used stereolithography (SLA) technology; and an M2 Carbon (Carbon®, Redwood City, CA, USA), which used Continuous Liquid Interface Production™ (CLIP) technology. The master cast and all models generated from each group were digitized using the same IOS. Accuracy was evaluated digitally and laboratory. The obtained STL files were superimposed on the master cast STL file (reference) to evaluate the 3D accuracy digitally with inspection software (Geomagic Control X; 3D Systems) using the root mean square value (RMS). For prosthesis assessment, an implant screw-retained fixed zirconia prosthesis was fabricated and tested on each cast. Accuracy of fit was assessed using a screw resistance test and radiographic test. Results: The highest median RMS was found in the stone model group (94.6 μm) and the lowest median was in the M2 Carbon group (46.9 μm). The Kruskal-Wallis test revealed a statistically significant difference between the groups (p<0.001). For post-hoc comparisons, Dunn’s test with the Holm-Bonferroni correction resulted in a statistically significant difference in the four tests. The lowest p-value was for the comparison between the M2 Carbon and P30+ groups (p=0.002), with M2 Carbon exhibiting a significantly lower (RMS). The zirconia prosthesis fits adequately on all casts. Conclusion: Within the study’s limitations, the M2 Carbon printer in virtual analysis demonstrated statistically significant lower 3D deviations in root mean square than the Straumann® P30+ printer. Printed casts generated from M2 Carbon, Formlabs® Form 3b and BEGO® Varseo S demonstrated statistically significant lower 3D deviations in root mean square than stone models generated using a conventional implant impression for the present partially edentulous scenario with two implants. Using a screw-resistance test and radiographic assessment, the zirconia prosthesis fit was clinically acceptable on all models.20 0