ABSTRACT
Objective:To explore the influence of the veneering porcelain thickness on the compressive strength of zirconia all-ceramic crown.Methods:25 zirconia basement crowns with the thickness of 0.5 mm were made by CAD-CAMsystem,and then were divided into 5 groups randomly with the veneering porcelain thickness of 0.5(A),1.0(B),1.5(C),2.0(D)and 2.5 mm(E)respectively. The compressive strength of the samples was measured by a testing machine.Statistical analysis was conducted by SPSS13.0 software. The microstructure of the fractured bonding interface of the specimens was observed by scanning electron microscope(SEM).Results:The compressive strength in group A,B,C,D and E were:(1 279.96 ±42.85)N,(2 235.44 ±50.14)N,(2 216.38 ±48.97)N, (2 169.22 ±60.40)N and (2 028.70 ±47.37)N respectively(A or E vs B,C or D,P 0.05;C vs D,P >0.05).SEMobservation found that in group A and E the bonding interface was uneven and loose,the cracks and spores in veneering porcelain appeared more and larger,and had a more intensive distribution.Conclusion:When the veneering porce-lain is too thick or too thin,the compressive strength of zirconia all-ceramic crown decreases,the thickness of the veneering porcelain should be controled in an appropriate range.