A Micro-computed Tomography Analysis of Marginal and Internal Fit of Endocrowns Fabricated from Three CAD/CAM Materials
To assess the marginal and internal misfit of endocrowns fabricated from a resin matrix ceramic (CS), a partially crystallized (EMC), and a fully crystallized (ILS) lithium disilicate glass-ceramic. Thirty human premolar teeth restored with endocrowns were investigated. Three CAD/CAM materials were used (n=10 per group): CS, EMC, and ILS. Two-dimensional (2D) analysis of marginal and internal misfit was performed on micro-computed tomography scans before and after adhesive bonding. Further, three-dimensional (3D) analysis was performed to determine the total internal volume discrepancy. Surface roughness of the fitting surfaces of endocrowns was characterized using optical profilometry and scanning electron microscopy. Adhesive bonding did not significantly affect marginal or internal misfit (p≥0.093). Differences in marginal misfit among the experimental groups were not statistically significant (p≥0.221). However, differences in 2D internal misfit were statistically significant; the CS group exhibited the largest internal misfit (p=0.001), while no significant difference was found between other groups (p=0.123). The largest discrepancies were observed at the pulpal floor and cervical region of all investigated specimens. No statistically significant difference was found in 3D misfit between ILS and EMC groups (p=0.711); however both exhibited statistically lower 3D misfit values compared to the CS group (p≤0.037). ILS endocrowns exhibited the smoothest and most homogenous fitting surface profile (p<0.001). However, there was no significant correlation between 2D internal misfit and the surface roughness (p≥0.082). The choice of CAD/CAM material may influence the fitting accuracy of endocrowns. The investigated lithium disilicate glass-ceramics conferred superior internal fit for endocrowns compared to resin matrix ceramic.SUMMARY
Objective
Methods and Materials
Results
Conclusions
Schematic representation of endocrown preparation features.
Micro-CT (μCT) sections: A horizontal cut of μCT-scan image presenting the selection of six sections through the center of the tooth and positioned at angles equally distributed from each other.
Measurement reference points: Measurement points for marginal and internal fit in a half cross-sectional cut of CT scan. MD: marginal discrepancy, AMD: absolute marginal discrepancy, C1 and C2: cervical discrepancies, A1 and A2: axial discrepancies, and P1 and P2: pulpal discrepancies.
3D internal fit analysis: A representative 3D reconstructed μCT image of the internal space (blue layer) for a CS (resin matrix ceramic) endocrown.
Surface roughness profile: SEM (scanning electron microscope) micrographs (left 1000×, middle 5000×) and profilometry generated height maps (right 200 × 200 μm) showing the initial surface topography of representative specimens from the three experimental groups.
Contributor Notes