Accuracy of 3D Printed Models Generated from Full-Arch Digital Implant Impressions Versus Stone Casts generated from Conventional Impressions: A Comparative Study
AlFulaij, Fahad.
2020
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Thesis (M.S.)--Tufts University, 2020.
Submitted to the Dept. of Posthodontics.
Advisor: Panagiotis Papaspyridakos.
Committee: Khaled El Rafie, Yo-Wei Chen, Matthew Finkelman, and Yukio Kudara.
Keyword: Dentistry.
Aim: To evaluate the accuracy of three-dimensional(3D) printed casts from 3 different printers (generated from full-arch digital implant ... read moreimpressions via an IOS scanner) compared to stone casts generated from conventional implant impressions for fully edentulous patients. Hypotheses: 1- The stone casts generated from conventional full-arch impressions will exhibit better accuracy than the printed casts generated from digital impressions from the 3 different 3D printers for completely edentulous patients. On the other hand, the printed casts generated from the three printers will demonstrate similar accuracy 2- The zirconia framework fabricated on the master (reference) cast will be seated on all casts and will demonstrate better accuracy of fit in the conventional stone casts compared to the 3D printed models. Materials & Methods: A maxillary stone cast with 4 abutment-level implant analogs (Screw-Retained Abutments, SRA, Straumann) with adequate antero-posterior (AP) spread simulated a common clinical condition. This stone cast served as the master (reference) cast for taking conventional and digital impressions. The conventional impression was taken with Polyether material (Impregum, 3M ESPE, St. Paul, MN) using the open-tray technique and the resulting stone casts (n=10) formed the control group. The digital impressions of the master cast were taken using a white light IOS (TRIOS, 3Shape) producing the Standard Tessellation Language (STL) files. These STL files were saved and then exported to 2 Digital Light Processing (DLP) and 1 Stereolithographic (SLA) 3D printers to produce a total of 30 printed models (n=10 from each 3D printer). The Varseo by Bego and the P30+ by Straumann represented the DLP printers, while the Form3B by Formlabs represented the SLA 3D printer. Accuracy was evaluated in two methods: 1. Digitized STL files by a high resolution extra-oral scanner (Dental Wings Series 7, Straumann) were super-imposed with digitized STL file from the master cast to compare the 3D accuracy in the inspection software (Geomagic, Control X) 2. The fit of a screw-retained zirconia prosthesis fabricated on the reference master cast was tested on all casts. Two blinded clinicians tested the accuracy of fit of the framework on all casts (conventional and 3D printed) utilizing the screw-resistance test. Furthermore, radiographs were taken to assess the accuracy of fit of the zirconia framework. Results: The conventional group exhibited the lowest mean RMS value (51.2 µm, SD= 19.5 µm), followed by the Varseo Bego group (64.1 µm, SD= 14.1 µm). The Form3b Formlabs group came next with (73.6 µm, SD= 10.4 µm) and the P30+ Straumann group had the highest mean RMS value (88.0 µm, SD= 7.2 µm). The Shapiro-Wilk test revealed that the data were not normally distributed (p<0.05 in the Form3B group). Hence, the independent-samples Kruskal-Wallis test was used, resulting in a significant difference between the groups (p<0.001). Post-hoc testing was used in the form of Dunn's test with the Holm-Bonferroni method of sequential correction, which revealed a significant difference between the following groups: conventional vs. P30+, Conventional vs. Form3B, and Varseo vs. P30+. Regarding the accuracy of fit of the zirconia framework, the screw resistance test yielded the following results: all models of the conventional, Varseo, and Form3B groups demonstrated acceptable fit. However, only 3 out of the 10 models in the P30+ group exhibited acceptable fit while the remaining 7 were deemed unacceptable. The Chi-square test was used and was significant (p<0.001) Conclusion: Within the limitations of this study, the conventional stone casts fabricated from open-tray splinted impressions demonstrated higher accuracy than both the Form3B & P30+ printed models generated from digital impression with a TRIOS scanner. Within the printed models, the Varseo group had better accuracy than the P30+ group. Lastly, the conventional group, as well as the Varseo and Form3B groups, demonstrated acceptable fit with the screw-resistance test and were superior to the P30+ group which had misfits in 7 out of the 10 models in the group.read less - ID:
- 8049gk78r
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