Introduction: The aim of this in vitro study was to investigate the influence of different scan paths on the accuracy of digital full arch impressions obtain - ed by 3 scanning systems.
Materials and methods: A maxillary model with 14 prepared teeth was digitized with a reference scanner (ATOS III Triple Scan) and 3 test scanners (CS 3500, CEREC Omnicam and True Definition) using 7 different scan paths. In test path 1 and 2, the manufacturers’ suggested scan paths were investigated. In test path 3, 4, and 5 shorter scan paths were utilized. For comparison, a randomly selected scan path was performed in test path 6. Test path 7 was a repetition of scan path 1 to investigate whether there was a learning effect. The scans were digitally superimposed (Geomagic Control), values for trueness and precision were evaluated and statistical analyses performed.
Results: Path 4 (trueness: 32.7 ± 10.3 μm, precision: 23.8 ± 9.5 μm) and path 5 (trueness: 35.1 ± 10.7 μm, precision: 24.2 ± 10 μm) revealed the highest accuracy. For trueness measurements of Omnicam, no statistically significant differences were found between individual scan paths. Overall, path 7 showed a higher accuracy than path 1, however, the differences were not statistically significant.
Conclusion: Ideally, the selected scan path should be as short as possible, and long-distance scans should be avoided. The accuracy of Omnicam appeared not to be dependent on a specific scan path. For all three scanners, the accuracy was clinically acceptable, however, the scan of a prepared full arch with a point-and-click system (CS 3500) cannot be recommended.
Keywords: computerized optical impression making, digital impression, optical impression, scan path; scan pattern
