饰面瓷厚度对氧化锆全瓷冠抗压缩破坏力的影响

目的：研究饰面瓷厚度对氧化锆全瓷冠抗压缩破坏力的影响。方法：常规 CAD-CAM制作氧化锆筒状基底冠25个，厚度均为0．5 mm，随机分为 A、B、C、D、E 5组，饰面瓷厚度依次为0．5、1．0、1．5、2．0、2．5 mm。万能材料试验机测试各组试件抗压缩破坏力值。采用 SPSS13．0统计软件对测试结果进行统计分析。用扫描电镜（SEM）观察试件断裂面微观结构。结果：A ～E 组试件抗压缩破坏力值依次为：（1279．96±42．85）N、（2235．44±50．14）N、（2216．38±48．97）N、（2169．22±60．40）N、（2028．70±47．37）N。A 组、E 组氧化锆全瓷修复体的抗压缩破坏力值均低于其他3组（P ＜0．01）；其余组间抗压缩破坏力值无统计学差异（P ＞0．05）。扫描电子显微镜观察发现，A 组、E 组氧化锆全瓷修复体基底瓷－饰面瓷结合界面处不平坦，较为疏松；饰瓷层出现气孔及微裂纹增多、增大。结论：饰面瓷厚度低于1．0 mm 及高于2．0 mm 时，修复体的微观结构可能会受到影响，从而氧化锆全瓷冠整体抗压缩破坏力的性能受影响，建议临床应用时严格控制饰面瓷厚度。

Influence of veneering porcelain thickness on the compressive strength of zirconia all-ceramic crown

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 <0.01;A vs E,P <0.01;B vs 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.