Use of measuring gauges for in vivo accuracy analysis of intraoral scanners:a pilot study

ABSTRACT

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.