三种二硅酸锂玻璃陶瓷冠抗折强度研究

Study on fracture resistance of different lithium disilicate materials

目的通过抗折破坏实验分析3种牙科二硅酸锂玻璃陶瓷抗折强度的差异,为国产二硅酸锂玻璃陶瓷临床应用提供依据。方法将30个下颌第一磨牙标准预备体代型随机分为3组,每组10个,分别制作国产二硅酸锂玻璃陶瓷冠试件(DID组)、IPS e.max CAD冠试件(IPC组)和IPS e.max Press冠试件(IPP组)。3组全瓷冠试件粘接后,分别放置于电子万能试验机上,用直径6 mm圆形加载头,以0.5 mm/min速度垂直加载于全瓷冠面中央至瓷层碎裂,记录最大载荷,即二硅酸锂玻璃陶瓷冠抗折强度。用扫描电镜(SEM)观察表面形态。采用SPSS21.0统计软件对3组全瓷冠试件抗折强度值进行单因素方差分析和组间两两比较的q检验,检验水准取双侧α=0.05。结果 3组全瓷冠试件抗折强度结果:DID组为(949.7±119.4)N,IPC组为(1746.9±244.8)N,IPP组为(2161.8±239.0)N。3组间总的比较,差异有统计学意义(F=86.685,P<0.05);各组间两两比较,差异亦均有统计学意义(均P<0.05)。3组全瓷冠试件的断裂模式无显著差异,大部分试件断裂类型均为Ⅰ型。SEM观察,DID组可见晶体在样本中分布不均匀,大小不一,表面有细小裂隙;IPC组可见析出晶体在样本中分布较均匀,晶体较为长大;IPP组可见析出的棒状二硅酸锂晶体均匀分布于玻璃相中,互相嵌合,并形成一种互锁微结构。结论研究条件下,不同二硅酸锂玻璃陶瓷对抗折强度及断裂类型均有影响,国产二硅酸锂玻璃陶瓷可以满足临床要求,对于其在临床应用有一定指导意义。

Objective To investigate the fracture resistance of different lithium disilicate crowns by mechanical test.Methods Totally 30 epoxy dies crowns were divided into 3 groups.They were cemented to domestic lithium disilicate glass-ceramic crowns in Group DID,to IPS e.max CAD crowns in Group IPC and to IPS e.max Press crowns in Group IPP respectively.Use the universal testing machine to survey the flexural strength.Stainless steel ball with a diameter of 6 mm was vertically placed on the occlusal surface of the crowns at a speed of 0.5mm/min.Fracture was defined as occurrence of chipping.The loads at fracture were registered;scanning electron microscopy （SEM） was used to observe cross-section morphology.SPSS21.0 was used to analyze the fracture resistance of the three groups,the standard being α =0.05.Results The mean fracture resistance of the domestic lithium disilicate glass-ceramic crowns was （949.7 ±119.4） N,IPC group （1746.9 ± 244.8） N,IPP group （2161.8 ± 239.0） N.The difference among the three groups was statistically significant （F =86.685,P ＜ 0.05）.The difference had statistical significance （P ＜ 0.05） when the groups were compared in pairs.The fracture mode of the three groups of all-ceramic crowns had no significant difference,and the fracture mode was mostly type Ⅰ.Under SEM,all sizes of crystals with fine cracks on surface could be seen unevenly distributing in samples of group DID;the big and long crystals could be seen relatively evenly distributing in samples of group IPC,and in group IPP,the rodlike lithium disilicate crystals were evenly distributed in glass phase,interdigitated,and formed an interlocking microstructure.Conclusion In the study,different lithium disilicate glass-ceramic crowns have influence on fracture resistance and fracture mode,and domestic lithium disilicate porcelain can meet the clinical requirement,which has certain guiding significance for its clinical application.