Journal of Dentistry
Volume 34, Issue 8 , Pages 566-573, September 2006

The influence of capsule geometry and cement formulation on the apparent viscosity of dental cements

  • C.M. Crowley

      Affiliations

    • Materials Ireland Research Centre, University of Limerick, Ireland
    • Corresponding Author InformationCorresponding author at: Materials Ireland Research Centre, University of Limerick, National Technology Park, Limerick, Ireland. Tel.: +353 61 213009; fax: +353 61 202967.
    • ,
  • J. Doyle

      Affiliations

    • Materials Ireland Research Centre, University of Limerick, Ireland
    • ,
  • M.R. Towler

      Affiliations

    • Materials and Surface Science Institute, University of Limerick, Ireland
    • ,
  • R.G. Hill

      Affiliations

    • Department of Materials, Imperial College, London, United Kingdom
    • ,
  • S. Hampshire

      Affiliations

    • Materials Ireland Research Centre, University of Limerick, Ireland
    • Materials and Surface Science Institute, University of Limerick, Ireland

Received 13 July 2005; accepted 24 August 2005.

Abstract 

Objectives

This work examines the influence of specific aspects of capsule design and cement formulation on the handling properties of the extruded glass polyalkenoate cement (GPC) pastes.

Methods

A commercial metal reinforced GPC, HiDense, and experimental GPCs were extruded using a tensometer at loads and rates maintained within end-user limits and the apparent viscosity of the cement paste was determined by applying Poiseuille's law. The influence of the extrusion procedure (mixing time and ram speed), capillary geometry (length and diameter) and cement composition (powder: liquid (P:L) ratio, tartaric acid content and poly(acrylic acid) molar mass) on the apparent viscosity of the cement paste was evaluated.

Results

The examined GPCs behaved as non-Newtonian, pseudoplastic materials and exhibited a yield stress. Variation of the geometry of the capsule capillary resulted in the apparent viscosity of HiDense increasing by 7% as the length increased from 5 to 15mm whilst halving the capillary diameter from 2 to 1mm resulted in a 63% decrease in the apparent viscosity and a 600% increase in the extrusion load. The apparent viscosity of the experimental GPCs was increased by an increase in the P:L ratio and, in general, by the PAA molar mass, whilst the concentration-dependent effect of (+)-tartaric acid (TAA) indicates a working time dependence on TAA content.

Conclusions

Using this approach optimisation of the rheological properties can be achieved by manipulation of the capsule design and cement formulation due to the dependency of the apparent viscosity on the capillary diameter, TAA content, P:L ratio and poly(acrylic acid) molar mass.

Keywords: Glass ionomer cements, Encapsulation, Viscosity

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PII: S0300-5712(06)00035-2

doi:10.1016/j.jdent.2005.08.009

Refers to erratum:

  • Erratum to “The influence of capsule geometry and cement formulation on the apparent viscosity of dental cements” [J. Dent. 34 (2006) 566–573]

    C.M. Crowley, J. Doyle, M.R. Towler, R.G. Hill, S. Hampshire
    Journal of Dentistry January 2007 (Vol. 35, Issue 1, Page 93)

Journal of Dentistry
Volume 34, Issue 8 , Pages 566-573, September 2006

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