Purpose
To evaluate the fit of single crowns fabricated using conventional, digital, or cast
digitization methods.
Materials and Methods
One subject with a peg‐shaped maxillary lateral incisor was selected in this study.
Tooth preparation for an all‐ceramic crown was performed and 10 conventional poly(vinyl
siloxane) impressions, and 10 digital impressions using an intraoral scanner were
made. Each working cast was scanned using a laboratory scanner and an intraoral scanner.
Four groups were tested Group 1: conventional impressions. Group 2: cast laboratory
scans. Group 3: cast scans using intraoral scanner. Group 4: direct intraoral scans.
For group 1, heat‐pressed glass ceramic crowns (IPS e.max Press) were fabricated using
casts produced from the conventional impressions. For groups 2‐4, crowns were milled
using ceramic blocks (IPS e.max CAD). Ten crowns were fabricated for each group. Marginal
and internal gaps were measured using a replica technique. Replicas were sectioned
mesiodistally and buccolingually and were observed under a stereomicroscope. Three
measurements were selected for each cut: occlusal, axial, and marginal. Statistical
analysis was performed using two‐way ANOVA and Tukey HSD tests.
Results
For each replica, 6 measurements were made for the mesiodistal and the same for the
buccolingual cuts, producing 12 measurement points per crown (4 measurements for marginal,
4 for axial, 4 for occlusal), 120 measurements for each group (40 measurements for
marginal, 40 for axial, 40 for occlusal), and 480 measurements in total. Two‐way ANOVA
revealed location to be a significant factor (p = 0.001). No significant differences among groups (p = 0.456), and no interactions between groups and locations (p = 0.221) were found. Means for the occlusal site were significantly larger than other
sites in most group combinations, while the difference between the marginal and axial
sites was not significant. No significant differences among groups were found for
each measurement. The marginal gaps ranged from 125.46 ± 25.39 μm for group 3 to 135.59
± 24.07 μm for group 4. The smallest axial mean was in group 1 (98.10 ± 18.77 μm),
and the largest was 127.25 ± 19.79 μm in group 4. The smallest occlusal mean was in
group 2 (166.53 ± 36.51 μm), and the largest occlusal mean was in group 3 (203.32
± 80.24 μm).
Conclusions
Ceramic crowns, which were made using all‐digital approach or cast digitization by
a laboratory or intraoral scanner had comparable fit to those produced by conventional
approach.
Comments