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Kinetic studies of the effect of varnish on water loss by glass-ionomer cements

Kinetic studies of the effect of varnish on water loss by glass-ionomer cements

Nicholson, John W. and Czarnecka, Beata (2007) Kinetic studies of the effect of varnish on water loss by glass-ionomer cements. Dental Materials, 23 (12). pp. 1549-1552. ISSN 0109-5641 (doi:10.1016/j.dental.2007.02.004)

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Abstract

OBJECTIVES: This paper reports a study of the water loss behaviour of two commercial glass-ionomer cements coated with varnishes. METHODS: For each cement (Fuji IX Fast or Chemflex), specimens (6mmdiameterx2mm depth) were prepared and cured for 10min at 37 degrees C. They were exposed to a desiccating environment over H(2)SO(4) either uncoated or coated with the appropriate varnish (Fuji Varnish, a solvent-based lacquer, or Fuji Coat, a light-cured varnish). Four specimens were prepared for each material. They were weighed at hourly intervals for 6h, daily for up to 5 days, then weekly thereafter until equilibration. RESULTS: Unlike the uncoated specimens, water loss from varnished cements was not Fickian, but followed the form: mass loss=A/t+B, where t is time, A and B are constants specific to each cement/varnish combination. A varied from 1.22 to 1.30 (mean 1.26, standard deviation 0.04), whereas B varied from 1.54 to 2.09 (mean -1.83, standard deviation 0.29). At equilibrium, varnished specimens lost much less water than unvarnished ones (p>0.01) but there was no significant difference between the solvent-based and the light-cured varnishes. SIGNIFICANCE: Varnishes protect immature glass-ionomer cements from drying out by altering the mechanism of water loss. This slows the rate of drying but does not necessarily change the total amount of water retained. It confirms that, in clinical use, glass-ionomer restoratives should be varnished to allow them to mature satisfactorily.

Item Type: Article
Uncontrolled Keywords: glass–ionomers, water loss, varnish, drying, kinetics
Subjects: R Medicine > RK Dentistry
Q Science > QD Chemistry
Faculty / Department / Research Group: Faculty of Engineering & Science > Department of Pharmaceutical, Chemical & Environmental Sciences
Related URLs:
Last Modified: 09 Dec 2016 16:04
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/2517

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