Marginal Fit of Lithium Disilicate Crowns Fabricated Using Conventional and Digital Methodology: A Three-Dimensional Analysis

PurposeTo compare the marginal fit of lithium disilicate (LD) crowns fabricated with digital impression and manufacturing (DD), digital impression and traditional pressed manufacturing (DP), and traditional impression and manufacturing (TP). Materials and MethodsTooth #15 was prepared for all-ceramic crowns on an ivorine typodont. There were 45 LD crowns fabricated using three techniques: DD, DP, and TP. Microcomputed tomography (micro-CT) was used to assess the 2D and 3D marginal fit of crowns in all three groups. The 2D vertical marginal gap (MG) measurements were done at 20 systematically selected points/crown, while the 3D measurements represented the 3D volume of the gap measured circumferentially at the crown margin. Frequencies of different marginal discrepancies were also recorded, including overextension (OE), underextension (UE), and marginal chipping. Crowns with vertical MG > 120 m at more than five points were considered unacceptable and were rejected. The results were analyzed by one-way ANOVA with Scheffe post hoc test ( = 0.05). ResultsDD crowns demonstrated significantly smaller mean vertical MG (33.3 19.99 m) compared to DP (54.08 +/- 32.34 m) and TP (51.88 +/- 35.34 m) crowns. Similarly, MG volume was significantly lower in the DD group (3.32 +/- 0.58 mm(3)) compared to TP group (4.16 +/- 0.59 mm(3)). The mean MG volume for the DP group (3.55 +/- 0.78 mm(3)) was not significantly different from the other groups. The occurrence of underextension error was higher in DP (6.25%) and TP (5.4%) than in DD (0.33%) group, while overextension was more frequent in DD (37.67%) than in TP (28.85%) and DP (18.75%) groups. Overall, 4 out of 45 crowns fabricated were deemed unacceptable based on the vertical MG measurements (three in TP group and one in DP group; all crowns in DD group were deemed acceptable). ConclusionThe results suggested that digital impression and CAD/CAM technology is a suitable, better alternative to traditional impression and manufacturing.