Dimensional changes of resin/ionomer restoratives in aqueous and neutral media
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Date
2000Author
Watts, D. C.
Kisumbi Bernina k.
Toworfe, G. k.
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
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: resincomposite.
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 degrees C. Volumetric
changes of specimens (4 mm diameter x 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 degrees 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 degrees C,
however the RM-GIC expanded, indicating that its cure is temperature-sensitive. In water, at 23
and 37 degrees 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 timedependent
effects of an aqueous environment.
URI
http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/10343http://www.ncbi.nlm.nih.gov/pubmed/11203539
Citation
Dental MaterialsPublisher
Elsevier Science Ltd University of Nairobi Dental School, Nairobi, Kenya 'The University of Manchester Dental School, Higher Cambridge Street, Mar/chester M I 5 6FJ-I, UK bThe The University of Ghana Dental School, Accra, Ghana
Subject
Dental materials; Glass ionomer; Compomer; Dimensional change; Shrinkage; Hygroscopic expansionDescription
Dimensional changes of resin/ionomer restoratives in aqueous and neutral media
Collections
- Faculty of Health Sciences (FHS) [10378]