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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
engineering
Dimensional changes of resin/ionomer restoratives in aqueous and neutral media
Dental Materials, Volume 16, No. 2, Year 2000
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Description
Objectives: The aim was to study dimensional time-dependence of resin/ionomer formulations from 5 min age to one month and to separate out the intrinsic setting shrinkage and hygroscopic expansion effects, by using non-aqueous and aqueous storage media, respectively. Methods: Materials studied included: A: resin-, B: metal- and C: polyphosphonate-modified glass-ionomer cements [GICs]; and controls of D: poly-acid modified composite [compomer]; and E: resin-composite. Separate specimen groups (n = 5) were stored in different storage-media: (i) silicone fluid; (ii) de-ionized water. Experiments were repeated at 23 and 37°C. Volumetric changes of specimens (4 mm diameter × 6 mm height) were obtained via accurate mass measurements (to 10-4 g), using Archimedes principle, with silicone or water also used as the Archimedean fluid. These measurements were made periodically over a 30 day period, post fabrication. Results: In silicone at 23°C, all materials underwent further gradual intrinsic shrinkage (after 5 min from mix). This was highly significant (p < 0.05) for the RM-GIC (A). At 37°C, however the RM-GIC expanded, indicating that its cure is temperature-sensitive. In water, at 23 and 37°C, the shrinkage was either partially offset (materials C, D, E), or replaced by appreciable expansions (materials A and B). Differences between RM-GIC (A) and MM-GIC (B) were significant (p < 0.05). Significance: The deployment of dual storage media made an important contribution to the separate analysis of the volumetric changes due to the on-going setting chemistry in these systems and the time-dependent effects of an aqueous environment. © 2000 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.
Authors & Co-Authors
Watts, D. Christopher
United Kingdom, Manchester
Faculty of Biology, Medicine and Health
Kisumbi, Bernina K.
United Kingdom, Manchester
Faculty of Biology, Medicine and Health
Kenya, Nairobi
University of Nairobi School of Dental Sciences
Toworfe, George Kwamina
United Kingdom, Manchester
Faculty of Biology, Medicine and Health
Ghana, Accra
University of Ghana
Statistics
Citations: 83
Authors: 3
Affiliations: 3
Identifiers
Doi:
10.1016/S0109-5641(99)00098-6
ISSN:
01095641
Research Areas
Environmental
Health System And Policy