Saini Nikki, Kumar Sandeep, Aggarwal Rajnish, Choudhary Sunita, Tyagi Ritwik, Malethia Akhilesh
Department of Prosthodontics, Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan, India, Phone: +91 9530204146, e-mail:
Department of Prosthodontics, Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan, India.
J Contemp Dent Pract. 2020 Aug 1;21(8):852-856.
To compare the vertical margin accuracy of lost wax castings produced by the conventional casting technique with all metal (WIRONIUM®) and PFM alloy (WIRON®99) using a metal ring and ringless system.
A brass die assembly was used to fabricate standardized wax pattern crowns. A total of 100 wax patterns were made with both ringless and metal ring investment systems. Wax patterns were readapted and refined on the master die and divided into two groups, namely, group I and group II with 50 wax patterns in each group. Group I (ringless system) and group II (metal ring system) were further divided into subgroups having a sample size of 25 in each group. Each coping was invested and cast individually. The marginal discrepancy between the metal die and the castings were measured by a stereomicroscope and AutoCAD software 2013. Measurement was made on the facial area of the metal die.
The resultant casts obtained from different casting systems show statistically significant difference found between the marginal discrepancies using metal ring and ringless castings system, and statistically nonsignificant difference was found between the marginal discrepancies using all metal alloy (WIRONIUM®) and PFM alloy (WIRON®99) within the same group.
The marginal discrepancy for castings made with ringless casting system was less when compared to metal ring casting system, and there was no difference in marginal discrepancy when compared to all metal alloy (WIRONIUM®) and PFM alloy (WIRON®99) within the same group.
Marginal fit is influenced by several factors including type of crown, tooth preparation geometry, dimensional accuracy of impression materials, factors related to dental casting, type of cement, luting pressure, duration of cementation, and use of occlusal vents or die spacers.
比较使用金属环和无环系统，采用传统铸造技术，用全金属（WIRONIUM®）和烤瓷熔附金属合金（WIRON®99）制作的失蜡铸造件的垂直边缘精度。
使用黄铜模具组件制作标准化蜡型冠。使用无环和金属环包埋系统共制作100个蜡型。蜡型在母模上重新适配并修整，分为两组，即I组和II组，每组50个蜡型。I组（无环系统）和II组（金属环系统）进一步分为每组样本量为25个的亚组。每个内冠单独包埋并铸造。通过体视显微镜和AutoCAD软件2013测量金属模具与铸件之间的边缘差异。在金属模具的面部区域进行测量。
从不同铸造系统获得的最终铸件显示，使用金属环和无环铸造系统的边缘差异之间存在统计学显著差异，而在同一组内，使用全金属合金（WIRONIUM®）和烤瓷熔附金属合金（WIRON®99）的边缘差异之间存在统计学非显著差异。
与金属环铸造系统相比，无环铸造系统制作的铸件边缘差异较小，且在同一组内，与全金属合金（WIRONIUM®）和烤瓷熔附金属合金（WIRON®99）相比，边缘差异无差异。
边缘适合性受多种因素影响，包括冠的类型、牙体预备几何形状、印模材料的尺寸精度、与牙科铸造相关的因素、粘结剂类型、粘结压力、粘结持续时间以及咬合排气孔或代型间隙剂的使用。
