[Comparison of adaptation of crowns of different lithium disilicate glass-ceramic].

Objective: To evaluate the adaptation of different lithium disilicate glass-ceramic crown and whether different fabrication processes affect the adaptation of crowns.
Methods: Thirty epoxy dies crowns were divided into 3 groups. They were cemented to domestic lithium disilicate glass-ceramic crowns in Group A, to IPS e.max CAD crowns in Group B and to IPS e.max Press crowns in Group C respectively. All crowns were cut by cutting machine. A confocal laser scanning microscope was used to measure the gap between crown tissue surface and die.
Results: There were significant differences in the three groups of measurement points(P<0.05). Within the groups, specimens in group A showed in the lowest marginal fit([46.8±9.1] μm). Those in group B showed the lowest shoulder suitability([59.3±7.9] μm), axial plane([50.5±3.6] μm) and occlusal surface([87.6±11.6 μm]. Those in group C demonstrated the lowest axial plane angle[(84.4±10.1) μm]. In addition to the axial plane angle, the CAD/CAM system exhibited good accuracy of fit.
Conclusions: The three groups of lithium disilicate glass-ceramic crowns appeared to have clinically acceptable fit.