Full-crown castings made with water-saturated and dry casting ring liners

Our plain-English summary of Full-crown castings made with water-saturated and dry casting ring liners, by F. Keyf, G. Erman (Journal of Biomaterials Applications, 2000).

The study

• Authors: F. Keyf, G. Erman
• Journal: Journal of Biomaterials Applications
• Published: 2000;14(4):399-408
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The carcinogenic potential of asbestos has led to the development of non-asbestos materials for use as casting ring liners. Cellulose paper are replacing asbestos paper. The brass die and crown were made to produce full crowns. The standardized wax pattern was replicated twenty-nine times. Two grooves were marked on the die and wax patterns. The marginal gaps between wax pattern and die shoulder were measured. Then, the wax specimens were divided into three groups. The dry ring liner and the water-saturated ring liner were used, in the third group, any liner was used. The castings were fabricated and were fitted on the die. Measurements were made of the distance separating the gingival margin of the castings from the shoulder on the die. Measurement points (X and Y) were the same points used for wax pattern measurement. The difference between wax pattern and casting was found to be statistically significant in all the groups (p = 0.0051). There was no statistically significant difference between groups on the comparative fit of the castings. The mean marginal space in the water-saturated liner group was 0.51 +/- 0.12 mm (X), 0.51 +/- 0.11 mm (Y), and in the dry liner group, the mean marginal space was 0.47 +/- 0.09 mm (X), 0.49 +/- 0.08 mm (Y). In the unlined group, they were 0.52 +/- 0.18 mm (X), 0.55 +/- 0.17 mm (Y). Use of dry ring lining material resulted in smaller marginal spaces between castings and the die than use of water-saturated cellulose ring lining material. The results demonstrated that the use of dry liners may improve the fit of castings to dies.

In plain English

This was a dental laboratory experiment, not a study of asbestos exposure or disease. The authors noted that concern over the carcinogenic potential of asbestos had led to non-asbestos casting ring liners, and they tested cellulose liners used dry or water-saturated. From a brass crown mold they made twenty-nine wax crown patterns and split them into three groups: dry liner, water-saturated liner, and a third group the tables call unlined. The patterns were cast in metal, and the marginal gap between each casting and the die shoulder was measured at two points, X and Y. In every group the gaps for the castings differed significantly from those for the wax patterns. Mean casting gaps were 0.47 mm (X) and 0.49 mm (Y) in the dry liner group, 0.51 mm (X and Y) in the water-saturated group, and 0.52 mm (X) and 0.55 mm (Y) in the unlined group. These differences between groups were not statistically significant. The authors concluded that dry liners may improve casting fit, but that any of the materials could produce consistently acceptable castings with an appropriate technique.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory experiment (dental materials study) comparing casting fit with dry versus water-saturated cellulose casting ring liners and no liner
• Who was studied: Twenty-nine standardized wax full-crown patterns made from a brass crown and die, cast in nonprecious metal alloy, at Hacettepe University, Ankara, Turkey. No people were studied. The number of patterns in each group is not stated in the text.
• Exposure: No asbestos was used or studied. The tested variable was cellulose casting ring lining material used dry or water-saturated (soaked in water for 1 minute), compared with a third group described as unlined.
• Main results:
  • In each group, the marginal gaps of the castings differed significantly from those of the wax patterns: p = 0.0051 in the dry liner and water-saturated liner groups, and p = 0.0077 in the unlined group.
  • Mean marginal gap of castings in the dry liner group was 0.47 mm at point X and 0.49 mm at point Y.
  • Mean marginal gap of castings in the water-saturated liner group was 0.51 mm at both points X and Y.
  • Mean marginal gap of castings in the unlined group was 0.52 mm at point X and 0.55 mm at point Y.
  • Differences between the three groups were not statistically significant at point X (chi-square 1.1862, p = 0.5526).
  • Differences between the three groups were not statistically significant at point Y (chi-square 1.0441, p = 0.5933).
• The authors' conclusion: The authors concluded that dry liners may improve the fit of castings to dies, but considered that any of the materials could produce consistently acceptable castings if used with an appropriate technique.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenic.

Related studies

• The fit of gold-alloy full-crown castings made with pre-wetted casting ring liners — E.F. Morey, R. Earnshaw (1992)
• The effect of casting ring liners on the potential expansion of a gypsum-bonded investment — R. Earnshaw (1988)
• Dimensional accuracy of small gold alloy castings. Part 4. The casting ring and ring liners — E.F. Morey (1992)
• An investigation of the potential biohazards associated with asbestos-substitute casting ring liners — G.J. Tulachka, W.A. Brantley, et al. (1987)
• Release of asbestos fibers during casting ring liner manipulation — D.R. Davis (1995)
• The accuracy of occlusal cusp height in cast crowns — J. Takahashi, M. Okazaki, et al. (1983)

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