Comparison of different optical digitizing systems for dental CAD/CAM data-acquisition

Objectives: Objective of this study was to compare different digitizing systems, which are used in established CAD/CAM-systems, concerning their precision when teeth of varied shape (molar or incisor) are digitized.

Methods: Ten non-contact optical digitizing systems (3shape D250, 3shape D640, Digiscan, Digiscan with Zoom, etkon es1, Lava Scan, Lava Scan ST, KaVo Everest Scan pro, ODKM 97, ZENO Scan S 100) were use for data acquisition. Duplicate gypsum dies were made form two master ceramic teeth that were prepared according to the general rules for all-ceramic restorations. Data was aligned to virtual CAD-models, which are identical to the corresponding ceramic masters. The three-dimensional deviations between digitized data and the CAD-models were calculated with a computer-aided procedure (geomagic).

Results: The quantitative 3D-analysis showed mean deviations from +7/-4 µm to ±29 µm as well as maximum deviations between+41/-36 µm and +85/-98 µm. Eight of the ten systems showed high precision and deviation below or equal to ±15 µm. Statistical analysis (ANOVA, SPSS 16.0) revealed a significant influence of the kind of digitizing system. In contrary to findings for the complete fabrication process, the tooth shape was of inferior influence.

Conclusion: As the major number of digitizing systems are very close regarding their precision, factors such as tolerance of undercuts, type and colour of gypsum, handling and last but not least cost-benefit ratio are of importance.

This study was sponsored by 3M ESPE, Germany.