酸蚀时间及树脂粘接对二硅酸锂玻璃陶瓷弯曲强度的影响

摘要

目的 探究不同酸蚀时间以及树脂粘接对二硅酸锂玻璃陶瓷弯曲强度的影响,并评价树脂水门汀对玻璃陶瓷表面裂纹的修复能力,以期为临床全瓷冠粘接操作提供参考.方法 采用热压铸造工艺制作二硅酸锂玻璃陶瓷(IPS e.max(R) Press)杆状试件(25.0 mm ×3.0 mm ×2.0 mm)225个.打磨抛光后随机按排列表法将试件随机分为5组,每组45个.试件表面分别进行9.5％氢氟酸凝胶0(对照组)、20、40、60和120 s处理.各组3个试件进行场发射扫描电镜扫描观察.每组40个试件按随机排列表法随机分为两个亚组(每亚组20个),对1个亚组试件酸蚀表面涂布硅烷偶联剂和双固化型树脂水门汀,另一亚组不处理.再分别经37℃水储存24 h和水储存24 h+冷热循环10000次后进行三点弯曲测试.每组剩余2个试件粘接树脂后使用场发射扫描电镜观察粘接界面.对各组试件弯曲强度进行三因素方差分析.结果 氢氟酸酸蚀首先导致玻璃基质溶解消失,随着酸蚀时间的延长,部分晶体结构也因失去基质的支持而脱落消失.玻璃陶瓷表面粗糙度随酸蚀时间的延长而增大.氢氟酸处理0、20、40、60和120 s时试件弯曲强度分别为(384±33)、(347±43)、(330±53)、(327±67)和(317±41) MPa.树脂粘接后,除对照组(0 s)外,其余各组弯曲强度均比粘接前显著增加(P＜0.05),分别为(420±31)、(435±50)、(400±39)和(412 ±58) MPa.结论 长时间的氢氟酸酸蚀可导致二硅酸锂玻璃陶瓷弯曲强度降低,树脂粘接可弥补酸蚀导致的玻璃陶瓷强度损失.%Objective To analyze the effect of hydrofluoric acid (HFA) etching time and resin bonding on the flexural strength of IPS e.max(R) Press glass ceramic,and evaluate the efficacy of resin cements to seal the cracks of the etched ceramic.Methods Two hundred and twenty-five bars (25.0 mm × 3.0 mm × 2.0 mm) were made from IPS e.max(R) Press ingots using lost-wax,hot-pressed ceramic fabrication technology and randomly divided into five groups,forty-five each.In each group,the surfaces of ceramic bars were etched by 9.5％ HFA gel for 0,20,40,60 and 120 s respectively.Three specimens from each group were selected to observe the microstructure by the field emission scanning electron microscope (FE-SEM).Then each group were randomly subdivided into two subgroups (n =20).One subgroup were coverd with a thin (approximately 0.1 mm) layer of resin cement (Variolink N),whereas the other subgroup remained unaltered.Half of the specimens were stored in 37 ℃ water bath for 24 h and the other half went through thermocycle 10000 times before 3-point bending test to determine their flexural strength.Interfaces between resin cement and etched ceramic were examined with FE-SEM.Results FE-SEM results showed that etching with HFA resulted in preferential dissolution of glass ceramic,and partially supported crystals within the glass matrix were lost with the increasing of etching time.FE-SEM indicated that resin cement sealed the cracks and defects and bonded tightly to etched ceramic surface.The mean flexural strength values of group 0,20,40,60 and 120 s were (384 ± 33),(347 ± 43),(330 ± 53),(327 ± 67),and (317 ±41) MPa respectively.The mean flexural strength of each group except group 0 s increased significantly to (420 ±31),(435 ±50),(400 ±39),and (412 ±58) MPa respectively after the application of resin cement.Conclusions Overtime HFA etching could have a wakening effect on IPS e.max(R) Press glass-ceramic.The application of dual-curing resin cement can compensate the strength loss of the etched glass ceramic.