Assessment of the Kavo PREPassistant Scanner

Objectives: Determine whether the PREPassistant (Kavo Germany) accurately scans extracoronal preparations, acrylic provisional restorations, and wax patterns. Methods: Ten Full Gold Crown preparations (5 each of teeth #19 and #28), and 5 provisional restorations (tooth #19) were scanned and evaluated for completeness (lack of artifacts or voids in scan) and accuracy. Selected for tooth #19, with and without a provisional restoration, were 17 reference points and 6 reference angles on 3 planes; for tooth #28, 11 reference points and 4 reference angles on 2 planes were selected. Each preparation was scanned 5 times, resulting in “Student” scans (SS). An additional scan was designated as the “Instructor” scan (IS). The PREPassistant software recorded the differences (mm or degrees) between IS and SS. Also, 10 wax patterns on tooth #2 were scanned for completeness. The waxes included Kavo Everest Wax and different colors and types (hard, regular) of wax by Whip Mix Corp.

Results: For the crown prep (#19): 10 of 17 points, and 4 of 6 angles showed no significant difference between instructor and student scans (ANOVA, p < 0.05); similarly for crown prep (#28): 7 of the 11 points, and 3 of the 4 angles showed no significant differences. For the Provisional (#19): 15 of the 17 points, and 5 of the 6 angles showed no significant difference between instructor and student scans. Points at the Axio-Occlusal surfaces and the angle of the Lingual Axial wall showed the most variability. Only the KaVo wax patterns scanned completely. The 3D images of the other wax patterns were incomplete, exhibiting artifacts and voids.

Conclusion: The PREPassistant can be used for evaluating extracoronal preparations, provisional restorations and the Kavo Wax, as they generally scanned completely and accurately within 0.05 mm and 2 degrees of the Instructor Scan.