The effect of temperature on viscosity of root canal sealers

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The effect of temperature on viscosity of root canal sealers
Published article online:
24 Aug 2006
Issue online:
24 Aug 2006
Received 13 December 2005; accepted 18 April 2006
To cite this article: S. Lacey, T. R. Pitt Ford, X.-F. Yuan, M. Sherriff, T. Watson (2006) The effect of temperature on viscosity of root canal sealers
International Endodontic Journal 39 (11) , 860Ò866 doi:10.1111/j.1365-2591.2006.01154.x
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S. Lacey11Department of Biomaterials and Conservative Dentistry, Dental Institute, King's College London, London, T. R. Pitt Ford11Department of Biomaterials and Conservative Dentistry, Dental Institute, King's College London, London, X.-F. Yuan22School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, UK, M. Sherriff11Department of Biomaterials and Conservative Dentistry, Dental Institute, King's College London, London & T. Watson11Department of Biomaterials and Conservative Dentistry, Dental Institute, King's College London, London

Dr Susanna Lacey, Dental Institute, Floor 25, Guy's Hospital, London SE1 9RT, UK (Tel.: 0207 188 1162; fax: 0207 188 1159; e-mail: susanna.lacey@kcl.ac.uk).
Lacey S, Pitt Ford TR, Yuan X-F, Sherriff M, Watson T. The effect of temperature on viscosity of root canal sealers. International Endodontic Journal, 39, 860Ò866, 2006.

Abstract

Aim To test the hypothesis that there was no significant (α = 0.05) change in viscosity of commercially available root canal sealers with increase in temperature using a high-performance Advanced Rheometric Expansion System (ARES) rheometer.

Methodology Materials tested were Apexit, Tubliseal EWT, Grossman's, AH Plus and Ketac-endo. Cone-and-plate geometry was used (25-mm diameter, 0.1 radian and gap 0.051 mm). Measurements were carried out for steady-state viscosity at 25 and 37 ?C in the shear rate range of 0.001Ò50 s−1 at standardized relative humidity and within 30 min from the start of mixing. Five samples were taken for each sealer at each temperature.

Results At 25 ?C all sealers demonstrated shear thinning. At 37 ?C Grossman's (powder : liquid ratio 2 : 1 and 3 : 1) and Ketac-endo had a rapid rise in viscosity and early set whereas the other sealers were shear thinning. On increasing temperature from 25 ?C to 37 ?C, Apexit, Tubliseal and AH Plus had reduced viscosity whereas Grossman's 2 : 1, Grossman's 3 : 1 and Ketac-endo had increased viscosity, which varied with the shear rate. The change in viscosity with change in temperature was significant (P < 0.05) for all sealers except AH Plus.

Conclusions There was a variation in the effect of increasing temperature on each sealer depending on the shear rate. With the exception of AH Plus, a significant (P < 0.05) change in viscosity was found, and the null hypothesis was rejected.

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