The purpose of this study was to evaluate the influence of fabrication methods of Lithium disilicate reinforced glass-ceramic crown on marginal and internal fit.
Lithium disilicate reinforced glass-ceramic crowns were fabricated using ingots for heat press forming and blocks for CAD/CAM milling manufactured by Hass and Ivoclar/Vivadent.
Dentiform of maxillary central incisor was prepared with a 6° taper and 1㎜ deep chamfer margin and duplicated with silicone, then polyurethane resin was poured at silicone mold to produce working model. Thirty-six working models were produced. The specimens were prepared by dividing groups into each method : ECM(IPS e.max CAD), EPC(Conventional wax-up & IPS e.max press), EPM(Wax block milling & IPS e.max Press), ABM(Amber Mill), APC(Conventional wax-up & Amber Press), APM(Wax block milling & Amber Press).
Marginal and internal fit were measured by the Replica technique. Light body silicone is placed between the specimen and the abutment and a constant load is applied. Then, after the light body silicone is cured, the specimen is separated from the model. Light body silicone layer was filled with regular boby silicone. The silicon reproduction is cut into Labio-Lingual section and Mesio-Distal section and the thickness of the light body silicon is measured. Fourteen reference points were determined and measured using a microscope.
As a result of calculating and comparing the average value of 14 points in all groups, the measured value was within 120 μm, the clinically acceptable range suggested by McLean and von Fraunhaufer (1971). In all groups, the marginal fit was smaller than the internal fit.
At the Margin area, a significant difference appeared only between the ECM group and the EPM group, and there was no statistically significant difference between the remaining groups. Deep chamfer has the best fit in ECM and ABM groups manufactured by CAD / CAM method. The ACM and the EPM group showed superior fitness in the Axial wall and the Incisal compared with the EPC and EPM groups, and the ABM group and the APC group showed statistically significantly better fitness than the APM group.