In the partial denture design, it is very complexe because of the fact that its range covers one missing tooth to a part of a remaining tooth and, for this reason, the relationship between the two are of various kinds.
In these conditions, it is required that a good refractory working model should be constructed for the purpose of manufacturing a cast plate that possesses a desirable fit. In other words, in designing a partial denture cast plate posessing a desirable fit a need is felt to investigate into various phases of dimensional changes of a refractory working model in detail from a clinical point of view.
In the present study, therefore, the author was concerned with 2 types of phosphate-bonded investment (Hi-vest D and Tai-vest) widely used in the manufacture of Co-Cr alloy cast plate and compared the differences between the effects of Kennedy's 4 kinds of defective types and 3 different impression taking methods (alginate, combined alginate with individual trays and combined alginate with commercially available trays) on a heatresistant model.