Lacey S, Pitt Ford TR, Watson TF, Sherriff M. A study of the rheological properties of endodontic sealers.
Int Endod J 2005;
38:499-504. [PMID:
16011766 DOI:
10.1111/j.1365-2591.2005.00953.x]
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Abstract
AIM
To test the hypothesis that there would be no statistically significant difference in viscosity-related measures of endodontic sealers or change in these with strain rate, internal diameter or powder : liquid ratio in a capillary system.
METHODOLOGY
Materials used were Apexit, Tubliseal EWT, Grossman's sealer and Ketac-endo. Viscosity-related measures were tested in a two-plate test, and in a capillary rheometer. The mean values (n = 12) for thickness and diameter of material formed between two glass plates were tested with one-way analysis of variance. Pressure was applied to a capillary rheometer at strain rates 5 and 10 mm min(-1) in tubes of internal diameter 0.6 and 1.2 mm.
RESULTS
Tubliseal EWT had a thinner film thickness than the other sealers (alpha = 0.05). The difference in diameter between Tubliseal EWT and the other sealers was significant apart from Apexit. Increased strain rate gave a significant increase (alpha = 0.05) in the flow of all sealers. Narrower tubes produced increased velocity, which was significant for all sealers, and reduced volumetric flow, which was significant for all sealers except Grossman's 2 : 1 (Wilcoxon signed rank test). Reduction in powder : liquid ratio of Grossman's significantly increased flow in narrow tubes and at higher strain rate (Mann-Whitney test).
CONCLUSION
There was a significant difference between the flow of Tubliseal EWT and the other sealers tested in the two-plate test; capillary flow was affected by sealer, internal diameter, strain rate and powder : liquid ratio. The null hypotheses were rejected.
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