Comparing the trueness of seven intraoral scanners and a physical impression on dentate human maxilla by a novel method

Abstract

Backgrounds: Intraoral scanner (IOS) accuracy is commonly evaluated using full-arch surface comparison, which fails to take into consideration the starting position of the scanning (scan origin). Previously a novel method was developed, which takes into account the scan origin and calculates the deviation of predefined identical points between references and test models. This method may reveal the error caused by stitching individual images during intraoral scan. This study aimed to validate the novel method by comparing the trueness of seven IOSs (Element 1, Element 2, Emerald, Omnicam, Planscan, Trios 3, CS 3600) to a physical impression digitized by laboratory scanner which lacks linear stitching problems. Methods: Digital test models of a dentate human cadaver maxilla were made by IOSs and by laboratory scanner after polyvinylsiloxane impression. All scans started on the occlusal surface of the tooth #15 (universal notation, scan origin) and finished at tooth #2. The reference model and test models were superimposed at the scan origin in GOM Inspect software. Deviations were measured between identical points on three different axes, and the complex 3D deviation was calculated. The effect of scanners, tooth, and axis was statistically analyzed by the generalized linear mixed model. Results: The deviation gradually increased as the distance from scan origin increased for the IOSs but not for the physical impression. The highest deviation occurred mostly at the apico-coronal axis for the IOSs. The mean deviation of the physical impression (53 ± 2 μm) was not significantly different from the Trios 3 (156 ± 8 μm) and CS 3600 (365 ± 29 μm), but it was significantly lower than the values of Element 1 (531 ± 26 μm), Element 2 (246 ± 11 μm), Emerald (317 ± 13 μm), Omnicam (174 ± 11 μm), Planscan (903 ± 49 μm). Conclusions: The physical impression was superior compared to the IOSs on dentate full-arch of human cadaver. The novel method could reveal the stitching error of IOSs, which may partly be caused by the difficulties in depth measurement.

Trueness of 12 intraoral scanners in the full-arch implant impression: a comparative in vitro study

“…Finally, the present study could have collected further and interesting data relating to the linear error increase during scan progression, if only the scan strategy had foreseen the departure from a specific sector of the physical model (x example, right posterior sector only). In fact, as previously reported [ 5 , 16 , 17 , 25 ] and recently confirmed by Walter Renne and colleagues in an in vitro study on a dentate model [ 42 ], the progression of the scan tends to bring with it an increase in percentage linear error. Unfortunately, this evaluation was not possible in the present study, since the operator was free to start from the right or left posterior area of the model indifferently; the data thus collected do not allow an evaluation of the exact percentage growth of the error along the progression of the scan.…”

Solid index versus intraoral scanners in the full-arch implant impression: in vitro trueness evaluation

“…Therefore, despite the enormous progress made in the accuracy of the IOSs, difficulties persist in scanning the completely edentulous patient, who needs prosthetic restorations with FA supported by 6 or more fixtures [ 3 – 5 ]. These are determined by the difficulty of the IOS to correctly read the distances between the different SBs, and the spatial and temporal progression of the scan [ 4 – 6 , 14 , 15 ]. SI also allows for control over the quality of the virtual models derived by the IOSs, using high-quality reference machines (CMM or industrial desktop scanners).…”

“…This process requires time and skills. Finally, the SI is not able to provide information on the patient’s soft tissues and the SI-derived model must, in any case, be integrated into a sequence of digital acquisitions obtained using IOS [ 13 , 14 ]. Further studies are needed to obtain more evidence on the use of SI in the impression of the completely edentulous patient who requires implant rehabilitation.…”

“…However, it is known from several in vitro studies that different IOSs demonstrate statistically different levels of accuracy [ 1 , 2 , 6 , 14 , 15 ].…”

The Digital Integrated Workflow in the Aesthetic Management of the Smile: A Case Report

“…The management of the scanned file is almost simultaneously with the scan and allows to evaluate the work performed and correct it with the patient still in the chair. This kind of work increases the comfort of the patient by reducing chair time [11]. Laboratory procedures can take place directly in a virtual CAD environment and make use of the printing of a stereolithographic model with removable dies.…”