BUTTON VERSUS BUTTONLESS CASTINGS FOR REMOVABLE PARTIAL DENTURE FRAMEWORKS

Casting removable partial dentures (RPDs) without completely filling t he sprue channels and generating casting buttons would result in savin g metal and making more defect-free castings. This investigation teste d whether a complete and sound RPD casting can be obtained when a mini mal amount of metal is used. A factorial experimental design, three sp ruing methods, two metal feeding directions, and two different weights of metal were used to cast 60 Kennedy class II, modification 1 RPDs. The metal used to cast each framework was either enough to result in a full button or in no button. Visual and radiographic examinations and counting of defects were made by two independent operators who were u naware of the spruing method, feeding direction, or amount of metal us ed to make the framework. The completeness of the casting and the pres ence of porosities were evaluated for clasps, major connectors, and me shworks. The use of minimal metal to cast RPDs was equally as successf ul as using enough for a full button, provided that the appropriate sp ruing arrangement and metal feeding direction were chosen. Indirect me tal feeding for maxillary RPDs was successful with the proper spruing arrangement.