The clinical accuracy of single crowns exclusively fabricated by digital workflow--the comparison of two systems

The purpose of the study was to compare the accuracy of crowns exclusively fabricated by the digital workflow of two systems. The null hypothesis stated was: Both systems do not differ with respect to marginal and internal accuracy.

In 14 patients, 13 molars and 1 premolar were prepared. Each preparation was scanned intraorally with two different digital impression systems, Lava COS and Cerec AC. On the basis of these data, Lava DVS crowns [DVS] and Vita Rapid Layering Technique crowns [RLT] were fabricated, respectively. Both systems contained of a zirconia framework and a digitally fabricated silicate ceramic veneering. The marginal and internal fit of the crowns was documented by a replica technique. The replicas were examined under microscope with a magnification of ×200. The Wilcoxon signed rank test was applied in order to test if the values of the two systems showed significant differences at p ≤ 0.05.

The results were as follows in micrometers (±standard deviation): at the marginal gap, 51 (±38) for [DVS] and 83 (±51) for [RLT]; mid-axial, 130 (±56) for [DVS] and 128 (±66) for [RLT]; axio-occlusal, 178 (±55) for [DVS] and 230 (±71) for [RLT]; and centro-occlusal, 181 (±41) for [DVS] and 297 (±76) for [RLT]. According to the Wilcoxon signed rank test, the results differed significantly at the marginal, axio-occlusal, and centro-occlusal gaps.

The null hypothesis had to be rejected.

The exclusively digital workflow on the basis of intraoral digital impressions delivered clinically satisfying results for single crowns with both systems.