Letzel H, Vrijhoef M M
J Oral Rehabil. 1984 Mar;11(2):95-101. doi: 10.1111/j.1365-2842.1984.tb00558.x.
A clinical study was conducted in which two operators made 180 class I or II amalgam restorations in a group of fifty-seven adult patients. The restorations were made in a series of six per patient. Each restoration was made of a different alloy (five conventional composition alloys and one high copper alloy). During a period of 5 years the marginal fracture formation of all restorations was yearly quantified with a 6-point photo rating scale. The quantifications were analysed as to their variance for the factors alloy, patient and operator. The relative importance of significant factors was calculated. The results show that for a period of 5 years the alloy, patient and operator all had a significant influence on the marginal fracture formation. The operator influence was stable in time. This factor was relatively small because the operator sample was highly selected. After 1 year the influence of the patient on marginal fracture was equal to that of the alloy. The patient influence in time was stable. However, the alloy influence increased considerably. The longer the service time of the amalgam restoration the more important becomes the influence of the alloy on the marginal fracture formation.
进行了一项临床研究，两名操作人员为一组57名成年患者制作了180个I类或II类汞合金修复体。修复体按每位患者6个的系列制作。每个修复体由不同的合金制成（五种传统成分合金和一种高铜合金）。在5年的时间里，所有修复体的边缘骨折形成情况每年用6分照片评分量表进行量化。对这些量化结果就合金、患者和操作人员等因素的方差进行分析。计算显著因素的相对重要性。结果表明，在5年的时间里，合金、患者和操作人员对边缘骨折形成均有显著影响。操作人员的影响在时间上是稳定的。由于操作人员样本经过高度筛选，该因素相对较小。1年后，患者对边缘骨折的影响与合金相当。患者的影响在时间上是稳定的。然而，合金的影响大幅增加。汞合金修复体的使用时间越长，合金对边缘骨折形成的影响就越重要。
