Journal of Dental Research, Vol 71, 1858-1864, Copyright © 1992 by International & American Associations for Dental Research Online Journals

ARTICLES

The fit of gold-alloy full-crown castings made with pre-wetted casting ring liners

E. F. Morey and R. Earnshaw
Department of Operative Dentistry, University of Sydney, Surry Hills, NSW, Australia.

Measurements were made of the fit of full-crown gold-alloy castings produced with two types of pre-wetted ring liner (asbestos and cellulose) and a typical gypsum-bonded investment (Cristobalite Inlay, Sybron/Kerr Products, Romulus, MI; W/P = 0.40). Laboratory measurements were made of the effects of the liners on potential investment expansion, and properties of the lining materials considered relevant to casting accuracy were also measured. There was a wide variation in values for mean dimensional inaccuracy. One liner produced a series of castings all of whose inaccuracies lay within the range +/- 0.1%, with a mean value of + 0.01%. With the other five liners, all or most castings were undersize. With three, all or most castings showed inaccuracies worse than -0.2%. The values for casting inaccuracy with the various liners showed a probable correlation with potential investment expansion (p < 0.05); however, no correlation was found between casting inaccuracy and any apparently relevant liner properties, alone or in combination. In casting techniques which use a pre-wetted ring liner, the choice of a specific lining material is an important factor which has a significant effect on casting inaccuracy. With at least three of the six liners tested, a higher investment expansion was needed for accurate full-crown castings to be ensured.

This article has been cited by other articles:

				F. Keyf and G. Erman Full-Crown Castings Made with Water-Saturated and Dry Casting Ring Liners J Biomater Appl, April 1, 2000; 14(4): 399 - 408. [Abstract] [PDF]