Lewis A J
J Prosthet Dent. 1978 Mar;39(3):278-81. doi: 10.1016/s0022-3913(78)80095-x.
Most of the removable partial denture castings examined showed radiographic evidence of internal porosity. In general the porosity ocurred in characteristic regions associated with abrupt changes in cross-sectional thickness. These were located either within the partial denture framework or at the casting-sprue junctions. The porosity is due to metal shrinkage caused by a premature solidification at some point, which in turn interferes with a controlled unidirectional soldification of the casting.
大多数检查的可摘局部义齿铸件都显示出内部孔隙的影像学证据。一般来说，孔隙出现在与横截面厚度突然变化相关的特征区域。这些区域要么位于局部义齿框架内，要么位于铸件 - 浇道连接处。孔隙是由于在某个点过早凝固导致金属收缩引起的，这反过来又干扰了铸件的受控单向凝固。
