Lewinstein I, Craig R G
Department of Restorative Dentistry and Biomaterials, Hebrew University, Hadassah School of Dental Medicine, Jerusalem, Israel.
J Oral Rehabil. 1990 Jul;17(4):303-10. doi: 10.1111/j.1365-2842.1990.tb00013.x.
The objectives of this study were to introduce a different method for evaluating the accuracy of impression materials using a vertical height gauge, and to determine the vertical (axial) and horizontal (transversal) changes of four impression materials. Comparison of means demonstrated the changes for addition and condensation type silicones, and larger changes for the agar/alginate combination and the visible light cured (polyetherurethanedimethacrylate) impression material. The results were in agreement with an earlier study of the agar/alginate combination, and the values for the condensation and addition silicones were about half those reported in previous studies. These small changes might indicate the use of a mandibular stock tray for the upper jaw when a putty/wash technique is employed. The findings suggest that, when the horizontal changes (delta X) of impressions taken with a mandibular stock tray have a negative sign (contraction), then the vertical changes (delta L) will have a positive value (expansion), and vice versa. Thus the pattern of distortion can be formulated as delta X/delta L less than 0.
本研究的目的是引入一种使用垂直高度规评估印模材料准确性的不同方法，并确定四种印模材料的垂直（轴向）和水平（横向）变化。均值比较显示了加成型和缩合型硅橡胶的变化情况，以及琼脂/藻酸盐组合和可见光固化（聚醚聚氨酯二甲基丙烯酸酯）印模材料的较大变化。结果与早期关于琼脂/藻酸盐组合的研究一致，缩合型和加成型硅橡胶的值约为先前研究报道值的一半。这些微小变化可能表明在采用油灰/冲洗技术时，对上颌使用下颌全口托盘。研究结果表明，当下颌全口托盘制取的印模水平变化（δX）为负号（收缩）时，垂直变化（δL）将为正值（扩张），反之亦然。因此，变形模式可表示为δX/δL小于0。
