Lai Pei-Ling, Huang Chun-Chen, Fu Po-Sung, Chen Jen-Hao, Lan Ting-Hsun, Chen Wen-Cheng, Hung Chun-Cheng
School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Division of Prosthodontics, Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
J Dent Sci. 2024 Dec;19(Suppl 1):S51-S60. doi: 10.1016/j.jds.2024.06.002. Epub 2024 Jun 13.
BACKGROUND/PURPOSE: High gold (Au) alloys have many advantages, such as good mechanical properties and stable chemical properties for dental restoration. The purpose of this investigation was to investigate the effect of zirconia (ZrO)-magnesia (MgO)-based investment combined with an argon arc vacuum pressure (Ar-arc VP) casting process on the recasting of high Au alloys.
The recasting Au alloys were compared between the control group of conventional SiO-based investment/horizontal centrifugal (HC) casting and the experimental group of ZrO-MgO-based investment/Ar-arc VP die casting. The first-generation castings were defined as being made from purchased Au alloys and the second-generation castings were made from 50 wt% of the original Au alloys before casting, plus the balance of the remaining 50 wt% from the previous castings. The third-generation was made from all old surplus from the previous castings. The ingots were measured for the marginal gap, surface roughness, interface oxidation, hardness, and phase identification.
The results showed that the recasting success rate reached 100%. The ZrO-MgO-based investment/Ar-arc VP group had better edge precision, smaller oxide layer thickness, and lower hardness than the SiO-based investment/HC group. However, surface roughness analysis indicated little difference between the two groups. Phase analysis showed that the recasting alloys of the second and third-generation groups contained higher Au contents than those of the first-generation.
Overall, the Au alloy can be better recasted and retain good mechanical properties under the clinically used 5 wt% ZrO2-MgO-based investment/Ar-arc VP casting method.
背景/目的：高金（Au）合金具有诸多优点，如良好的机械性能和稳定的化学性能，适用于牙科修复。本研究的目的是探讨氧化锆（ZrO）-氧化镁（MgO）基包埋材料结合氩弧真空压力（Ar-arc VP）铸造工艺对高Au合金再铸造的影响。
将再铸造的Au合金在传统SiO基包埋材料/水平离心（HC）铸造的对照组与ZrO-MgO基包埋材料/Ar-arc VP压铸的实验组之间进行比较。第一代铸件定义为由购买的Au合金制成，第二代铸件由铸造前原始Au合金的50 wt%加上前一次铸件剩余50 wt%的余量制成。第三代由前一次铸件的所有旧余量制成。对铸锭进行边缘间隙、表面粗糙度、界面氧化、硬度和相鉴定测量。
结果表明再铸造成功率达到100%。ZrO-MgO基包埋材料/Ar-arc VP组比SiO基包埋材料/HC组具有更好的边缘精度、更小的氧化层厚度和更低的硬度。然而，表面粗糙度分析表明两组之间差异不大。相分析表明，第二代和第三代组的再铸造合金比第一代含有更高的Au含量。
总体而言，在临床使用的5 wt% ZrO2-MgO基包埋材料/Ar-arc VP铸造方法下，Au合金可以更好地进行再铸造并保持良好的机械性能。
