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首页> 外文期刊>The Journal of Prosthetic Dentistry >Compositional stability and marginal accuracy of complete cast crowns made with as-received and recast type III gold alloy.
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Compositional stability and marginal accuracy of complete cast crowns made with as-received and recast type III gold alloy.

机译：用原样和重铸III类金合金制成的完整铸冠的成分稳定性和边缘精度。

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STATEMENT OF PROBLEM: The effect of combining new and recast metal on the compositional stability of the alloy used and accuracy of the final restoration is not known. PURPOSE: This study characterized the elemental compositional stability of as-received and recast type III gold alloy. The effect of combining these alloys on the marginal accuracy of complete cast crowns also was evaluated. MATERIAL AND METHODS: Sixty standardized type III gold alloy complete crowns were made on epoxy resin dies duplicated from a metal master die with conventional laboratory techniques. Three casting protocols (n = 20 each) were established in relation to the proportion of as-received and recast gold alloys: Group A (100% as-received metal), Group B (50% wt new metal, 50% wt once recast metal), and Group C (100% once recast metal). An elemental analysis was performed at 3 sites along the cast crown (cervical, middle, and occlusal) with x-ray energy-dispersive spectroscopy. Marginal accuracy was measured with a microscope before and after cementation. Results were subjected to 1-way analysis of variance followed by the Ryan-Einot-Gabriel-Welsch multiple-range test at a 1% level of significance. RESULTS: Elemental composition was significantly different among the casting groups (P<.001). The mean weight percentage values were 72.4% to 75.7% Au, 4.5% to 7.0% Pd, 10.7% to 11.1% Ag, 7.8% to 8.4% Cu, and 1.0% to 1.4% Zn. Statistically but not clinically significant differences also were found for marginal accuracy. The marginal discrepancy was less than 25 microm for all casting conditions, with the lowest value recorded for Group A (7 microm), the highest for Group C (12 microm), and an intermediate value for Group B (9 microm) specimens. CONCLUSION: Recasting type III gold alloys may adversely affect the marginal accuracy of complete cast crowns. In this study, however, such effects were not clinically significant.
机译：问题陈述：新金属和重铸金属的结合对所用合金的组成稳定性和最终修复的准确性的影响尚不清楚。目的：本研究表征了已接收和重铸的III型金合金的元素组成稳定性。还评估了这些合金组合对完整铸冠的边缘精度的影响。材料和方法：用传统的实验室技术，在从金属母模复制的环氧树脂模上制成60个标准化的III型金合金全冠。根据接收和重铸金合金的比例，建立了三种铸造方案（每组n = 20）：A组（100％的原样金属），B组（50％的新金属重量，一次重铸的50％重量）金属）和C组（100％一次重铸金属）。使用X射线能量色散光谱仪在铸造牙冠的三个部位（子宫颈，中间和咬合）进行了元素分析。在胶合前后，用显微镜测量边缘精度。对结果进行1分方差分析，然后以1％的显着性水平进行Ryan-Einot-Gabriel-Welsch多范围检验。结果：各铸造组之间的元素组成显着不同（P <.001）。平均重量百分比值为72.4％至75.7％的Au，4.5％至7.0％的Pd，10.7％至11.1％的Ag，7.8％至8.4％的Cu和1.0％至1.4％的Zn。在统计学上但在临床上没有显着差异，也发现边缘准确性。在所有铸造条件下，边际差异均小于25微米，A组的最低值（7微米），C组的最高值（12微米），B组的最高值（9微米）。结论：重铸III型金合金可能会对完整铸冠的边缘精度产生不利影响。然而，在这项研究中，这种作用在临床上并不重要。

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