Objective To investigate the effect of two different ring liner thickness on the deformation of resulted castings. Methods GC No.2 casting rings (50 mm in height and 39.5 mm in diameter) were lined with two dry ceramic fiber linerswith thickness of 0.70 mm and 0.45 mm. Plate-like wax patterns with pre-marked points were invested with a gypsum-bonded invest- ment and the rings were cast with a silver-based dental alloy. The difference between the castings and the wax patterns at corre- sponding points was calculated to represent the dimensional change of the investment in the rings at different directions.Results The expansion of the investment in the ringwas non-isotropic, with larger radial direction expansion than the axial direction expan- sion(P0.05).Conclusion The liners with two different thickness failed to eliminate non-isotropic deformation of the castings under the testing conditions of this study.
