Accuracy Evaluation of Digital versus Conventional Impression Techniques for Partially Edentulous Arches: An In Vitro Study.
Abstract: Abstract Statement of Problem: This study addressed the lack of data available on the accuracy of the Omnicam and True Definition digital scanners in partially edentulous patients. Purpose: The primary purpose of this study was to compare the accuracy of definitive casts acquired from digital implant impressions (digital implant-level impressions with scan bodies and an intraoral scanner... read more) using 2 different Intra Oral Scanners (CEREC Omnicam and 3M True Definition) with conventional implant impressions. A secondary purpose was to compare the difference in the accuracy of definitive casts between the Nobel Biocare and Straumann implant systems. Materials and Methods: Two partially edentulous mandibular master casts with two internal connection implant analogs with a 30° degree angulation between them (Tissue-Level implant analogs RN, Straumann and Replace Select implant analogs RP, Nobel Biocare) were used as master models (controls). 60 digital models were created from these two master models and assigned to 6 different groups. The first two groups, I and II, were produced by splinted open-tray implant-level impression procedures followed by digitization (n=10). The next two groups, III and IV, were produced by a digital impression procedure with a white light IOS (CEREC Omnicam; Sirona, Germany: n=10). The last two groups, V and VI, were produced by a digital impression procedure with a blue light IOS (True Definition: 3M ESPE, Germany: n=10 each). Accuracy was evaluated by superimposing the digital files of each cast in each test group to the digital file of the control (master cast) using a specific inspection software (Geomagic Control 2015). Medians ± interquartile ranges were calculated for all groups, and nonparametric tests (Kruskal-Wallis and Mann-Whitney U tests) were used to assess the statistical significance of differences. Results: The differences between the three impression groups of the Nobel implant system and the master model were statistically significant for all groups (p < 0.001), except for the Omnicam scan group (19.79 ± 4.25), and the True Definition scan group (15.36 ± 6.18 μm). The median ± interquartile range for the conventional group was 39.38 ± 17.71. There were significant differences between the three impression groups of the Straumann implant system and the master model (p = 0.003) for all groups, except the conventional impression group (21.77 ± 5.24 μm) and the True Definition scan group (16.94 ± 4.60 μm); the median ± interquartile range for the Omnicam group was 26.01 ± 15.03. The difference between the two implant systems for the conventional impression technique was significantly different (p < 0.001). The difference between the two implant systems for the Omnicam scanning system was significantly different as well (p = 0.011). The difference between the two implant systems for the True Definition scanning system was not significant. Conclusions: Within the limitations of this study, both the impression technique and the implant system affected the accuracy of the definitive models. The True Definition scanning system exhibited the best results compared to the other two techniques, although not all differences were statistically significant.
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Posthodontics.
Advisor: Panos Papaspyridakos.
Committee: Hans Peter Weber, Khaled El-Rafie, Matthew Finkelman, and Yukio Kudara.
Keyword: Dentistry.read less