Accuracy assessment (trueness and precision) of a confocal based intraoral scanner under twelve different ambient lighting conditions.

ABSTRACT

OBJECTIVES: The ambient lighting condition has been identified as an important factor that influences the accuracy of intraoral scanners (IOSs). The purpose of this study was to evaluate the influence of 12 different ambient lighting conditions on the accuracy of a confocal based IOS (PrimeScan). MATERIALS AND METHODS: A typodont was digitized using a laboratory scanner (L2i) to obtain a reference standard tessellation language (STLr) file. A restorative dentist recorded the scans using an IOS (PrimeScan) under 12 different ambient lighting conditions where the luminosity was measured using a light meter (LX1330B Light Meter). Twelve groups were created, namely 0-, 500-, 1000-, 2000-, 3000-, 4000-, 5000-, 6000-, 7000-, 8000-, 9000-, and 10 000 lux groups. Ten STL files were recorded per group. The STLr file was used as a reference with which to compare the distortion of the 120 STL files obtained using a software program (Meshlab). The normality Shapiro-Wilk test indicated that the distributions were not normal. Therefore, the nonparametric Kruskal-Wallis and pairwise multicomparison tests were used to analyze the data (α = 0.05). RESULTS: The group with the 1000 lux lighting condition obtained the smallest median ±interquartile range (IQR) with scanning distortion values of 69.5 ± 97.4 µm, followed by the 8000 lux group with a median ±IQR of 166.5 ± 318.1 µm. The 0 lx group presented the highest distortion values with a mean ±IQR of 355.5 ± 488.0 µm (p < 0.05). CONCLUSIONS: Ambient lighting conditions influenced the accuracy of the IOS tested. The highest accuracy values were obtained with 1000 lux. The lowest scanning accuracy was obtained with 0 lux.