醋酸及柠檬酸对牙科氧化锆陶瓷性能的影响

摘要

目的：评价两种典型食用酸（醋酸、柠檬酸）在常温下对牙科氧化钇稳定四方相氧化锆陶瓷（ Y⁃TZP ）机械性能和微观结构的影响，探讨食用酸对临床上Y⁃TZP修复体使用安全性的影响。方法制作30枚条状氧化锆陶瓷试样，随机分为6组，并进行以下处理：阴性对照组（ A组）试样不处理；阳性对照组（ B组）试样放入高压灭菌器，在134℃、0．2 MPa条件下加速老化20 h；酸溶液浸泡组试样分别于10％醋酸或20％柠檬酸溶液中浸泡7 d（ C组、E组）或14 d（ D组、F组）。测试表面维氏硬度，计算断裂韧性。各组典型试样以扫描电镜观察表面微观结构。结果醋酸和柠檬酸浸泡并未改变Y⁃TZP试样的表面维氏硬度。 D组断裂韧性显著降低。电镜下未发现6组试样表面微观结构的改变。结论常温下柠檬酸不会影响Y⁃TZP修复体的机械性能和微观结构；长期接触醋酸会造成Y⁃TZP断裂韧性的显著降低，影响Y⁃TZP修复体的临床使用寿命。%Objective To evaluate the effects of two kinds of typical edible acid ( acetic acid and citric acid ) on the mechanical properties and microstructures of yttria⁃stabilized tetragonal zirconia polycrystal (Y⁃TZP) at ambient temperature, and to investigate the safety of edible acids to Y⁃TZP restorations clinically. Methods 30 bar⁃shaped zirconia ceramics specimens were randomly divided in⁃to 6 groups. The specimens in the control group ( Group A) received no surface treatment, while those in group LTD ( Group B) were hydrothermally aged at 134 ℃ and 0.2 MPa in an autoclave for 20 hours. Specimens were immersed at ambient temperature in 10%acetic acid or 20% citric acid for 7 (Group C, E) or 14 days (Group D, F), respectively. Surface Vickers hardness and fracture toughness were measured. Scanning electron microscopy ( SEM) was used to observe the surface microstructure of each typical speci⁃men. Results Acetic acid and citric acid immersion didn’ t deteriorate the surface Vickers hardness. Specimens in Group D exhibited decreased fracture toughness. All the groups did not show significant microstructure changes on SEM observations. Conclusions Citric acid has no influence on the mechanical properties and microstructures of Y⁃TZP restorations at ambient temperature. Long⁃term immer⁃sion in acetic acid reduces fracture toughness of Y⁃TZP significantly and shortens the service life of Y⁃TZP restorations clinically.