Objective:The aim of this study was to investigate the masking ability of three kinds of lithium disilicate glass ceramics with different thicknesses on different backgrounds,hoping to put forward guidance for clinicians and technicians.Methods:Three kinds of lithium disilicate glass ceramics,IPS E.max Press LT,IPS E.max Press MO and IPS E.max Press HO,were made into disk specimens with four different thicknesses(0.4 mm,0.5 mm,06 mm,0.8 mm),which were cemented separately on four different backgrounds(precious gold alloy,nichel-chromium alloy,ND6 and ND8 composite resin).The baseline was using LT,MO and HO specimens with 0.8 mm thickness cemented on A2 composite resin.Measuring Lab value of each specimen by an optoelectronic colorimeter and calculating the ΔE value compared with the baseline.Results:No mater LT,MO or HO specimens,the ΔE values were decreased in all groups with thickness increasing(except for gold alloy group).When the thickness of ceramic was equal or greater than 0.5 mm,the ΔE values of HO groups were significantly less than MO and LT groups.When the thickness of ceramic was equal or less than 0.6 mm,the masking ability of the yellowish abutments was better than that of the greyish ones.When the thickness of ceramic was 0.8 mm,all the specimens had a preferable masking effect of all substrates,which were no significant difference.Conclusion:Both the type and thickness of ceramic and the color of background could affect the masking ability of lithium disilicate glass ceramics.For the dark abutments,using HO ceramic and/or increasing the thickness of ceramic may improve the masking effect.
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