MARGINAL AND INTERNAL FIT OF ENDOCROWNS FABRICATED WITH DIFFERENT RESTORATIVE MATERIALS

Objectives: Objectives of this study is to evaluate and compare the marginal and internal fit of endocrowns fabricated
from three CAD/CAM restorative materials—zirconia, lithium disilicate, and resin composite—using a standardized
digital workflow.
Methods: A sound mandibular first molar was endodontically treated and prepared with a standardized butt-joint
endocrown design (2 mm occlusal reduction, 4 mm intracoronal depth). The tooth was scanned using an intraoral
scanner, and 30 identical resin models were fabricated using a 3D printer. Endocrowns were designed in CEREC CAD
software with a 0 μm marginal spacer and 50 μm internal spacer, then milled from zirconia (IPS e.max ZirCAD®),
lithium disilicate (IPS e.max CAD®), and resin composite (Tetric CAD®), each group (n = 10). Zirconia and lithium
disilicate restorations underwent post-milling sintering and crystallization firing in dedicated dental furnaces (Programat
S1 1600® for zirconia and Programat CS6® for lithium disilicate) according to the manufacturers’ protocols, while
composite restorations (Tetric CAD®) required no additional firing. Marginal and internal gaps were assessed using the
Triple Scan Method (TSM) with a Medit i700 scanner and analyzed with Medit Crown Fit software. Statistical analysis
was performed using one-way ANOVA and Fisher’s LSD test (α = 0.05).
Results: For marginal fit Tetric CAD group exhibited the best marginal fit (73.7 ± 32.3 μm) followed by E-max CAD
(115.8 ± 47.3 μm), and ZirCAD group showed the worst fit (134.9 ± 59.4 μm), with a significant difference (p = 0.017)
among them. Pairwise comparison revealed a significant difference between ZirCAD and Tetric (p = 0.021). For internal
fit the Tetric CAD group exhibited the best overall internal fit (76.9 ± 16.19 μm), followed by ZirCAD group (89.9
±49.81), and E-max CAD showed the worst internal fit (114.1 ± 37.49 μm), with significant differences (p = 0.005)
among them, also significant differences were observed in cervical region (p = 0.009), axial region (p = 0.011), while
pulpal fit (p = 0.249) showed no statistically significant difference.
Conclusion: Within the limitations of this in-vitro study, the resin composite endocrowns (Tetric CAD) demonstrated
superior marginal and internal adaptation compared with lithium disilicate (IPS e.max CAD) and zirconia (IPS e.max
ZirCAD) restorations. These findings suggest that resin composite materials may provide a more accurate internal and marginal fit when fabricated through a fully digital CAD/CAM workflow.