PURPOSE: The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo . MATERIALS AND METHODS: A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles.Then, 10 scans were taken by an IOS with the gauge in the patient’s mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150angles were measured and compared with the gauge’s reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS: Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION Currently, there is no standardized procedure to assess the accuracy of IOS in vivo , and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.

PURPOSE: The purpose of this study is to assess the accuracy of three intraoral scanners along the complete dental arch and evaluate the feasibility of the assessment methodology for further in vivo analysis.MATERIALS AND METHODS: A specific measurement pattern was fabricated and measured using a coordinate measuring machine for the assessment of control distances and angles. Afterwards, the pattern was placed and fixed in replica of an upper jaw for their subsequent scans (10 times) using 3 intraoral scanners, namely iTero Element1, Trios 3, and True Definition. 4 reference distances and 5 angles were measured and compared with the controls. Trueness and precision were assessed for each IOS: trueness, as the deviation of the measures from the control ones, while precision, as the dispersion of measurements in each reference parameter. These measurements were carried out using software for analyzing 3-dimensional data. Data analysis software was used for statistical and measurements analysis (α=.05).RESULTS: Significant differences (P<.05) were found depending on the intraoral scanner used. Best trueness values were achieved with iTero Element1 (mean from 10 ± 7 µm to 91 ± 63 µm) while the worst values were obtained with Trios3 (mean from 42 ± 23 µm to 174 ± 77 µm). Trueness analysis in angle measurements, as well as precision analysis, did not show conclusive results.CONCLUSION: iTero Element1 was more accurate than the current versions of Trios3 and True Definition. Importantly, the proposed methodology is considered reliable for analyzing accuracy in any dental arch length and valid for assessing both trueness and precision in an in vivo study.
Dental Arch ; Jaw ; Jupiter ; Methods ; Pilot Projects ; Statistics as Topic

PURPOSE: The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo . MATERIALS AND METHODS: A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles.Then, 10 scans were taken by an IOS with the gauge in the patient’s mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150angles were measured and compared with the gauge’s reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS: Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION Currently, there is no standardized procedure to assess the accuracy of IOS in vivo , and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.