不同厚度全锆[牙合]贴面的断裂载荷及失效模式研究

Effects of thickness on fracture strength and failure mode of full-contour zirconia occlusal veneers

目的:探究牙合贴面厚度以及牙体预备形式对全锆牙合贴面的抗折性能及失效模式的影响。方法:预备标准人工磨牙形成3组不同形式的预备体:A组牙合面均匀磨除0.5 mm,B组牙合面均匀磨除0.5 mm,轴面包绕高度1.5 mm,C组牙合面均匀磨除0.5mm,并预备髓腔固位。采用CAD/CAM系统,通过Dental Designer软件,将每组分别设计为0.5 mm、1.0 mm、1.5 mm三种不同厚度,共制作出72个牙合贴面;测试不同牙体预备形式及不同厚度的牙合贴面的断裂载荷,并分析其失效模式。结果:不同牙体预备形式及不同厚度的全锆牙合贴面的平均断裂载荷值为:A组:(1275.9±205.6) N(0.5 mm厚度);(2320.6±296.7) N(1.0 mm厚度);(4909.1±399.3) N(1.5 mm厚度); B组:(1404.5±215.3) N(0.5 mm厚度);(2509.8±380.6) N(1.0 mm厚度);(4917.8±320.4) N(1.5 mm厚度); C组:(1279.6±248.4) N(0.5 mm厚度);(2346.6±260.2) N(1.0 mm厚度);(4575.3±458.7) N(1.5 mm厚度)。随着厚度的增加,全锆牙合贴面的抗折性能也随之增加,同一牙体预备形式不同厚度的断裂载荷有统计学差异,不同牙体预备形式同一厚度的断裂载荷无统计学差异。0.5 mm与1.0 mm组别的失效模式(修复体折裂)相似,与1.5 mm组别的失效模式(修复体与代型同时折裂)存在差异。结论:全锆牙合贴面厚度对其抗折性能有影响,抗折性能随着其厚度的增加而增大。牙体预备形式对牙合贴面的抗折性能没有影响。厚度为0.5 mm的全锆牙合贴面可以满足临床需要。

Objective:This study aimed to evaluate the effect of the thickness and tooth preparation on fracture strength and failure mode of full-contour zirconia occlusal veneer.Methods:Standard artificial molars of 3 different groups(n=72)were prepared:Group A:the occlusal surface was ground of evenly by 0.5 mm;Group B:the occlusal surface was ground of evenly by 0.5 mm,and the axial surface was parceled for 1.5 mm;Group C:the occlusal surface was ground of evenly by 0.5 mm,and cavity fixation was prepared.Three different models of full-contour zirconia occlusal veneers were designed with different thickness of 0.5 mm,1.0 mm,and 1.5 mm respectively using CAD/CAM system and Dental Designer software.Fracture strength and failure mode of zirconia occlusal veneers were measured and recorded.Results:The average fracture strength value of full-contour zirconia occlusal veneer with different thicknesses and different preparation were:Group A:(1275.9±205.6)N(0.5 mm thickness),(2320.6±296.7)N(1.0 mm thickness),(4909.1±399.3)N(1.5 mm thickness);Group B:(1404.5±215.3)N(0.5 mm thickness),(2509.8±380.6)N(1.0 mm thickness),(4917.8±320.4)N(1.5 mm thickness);Group C:(1279.6±248.4)N(0.5 mm thickness),(2346.6±260.2)N(1.0 mm thickness),(4575.3±458.7)N(1.5 mm thickness).Fracture strength of full-contour zirconia occlusal veneers increased in parallel with the increase of their thickness.Fracture strength of occlusal veneers with different thickness and preparation was significantly different,while that of occlusal veneers with the same thickness but different preparation showed no significant difference.The failure mode of 0.5 mm group was similar to that of 1.0 mm group but different from that of 1.5 mm group.Conclusions:Thickness is a positive correlation factor for the fracture strength of full-contour zirconia occlusal veneers.Preparation has no effect on the fracture strength of occlusal veneers.0.5 mm is an acceptable thickness for zirconia occlusal veneers in clinical practice.