dc.contributor.author | Watts, D. C. | |
dc.contributor.author | Kisumbi Bernina k. | |
dc.contributor.author | Toworfe, G. k. | |
dc.date.accessioned | 2013-02-19T14:03:50Z | |
dc.date.issued | 2000 | |
dc.identifier.citation | Dental Materials | en |
dc.identifier.uri | http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/10343 | |
dc.identifier.uri | http://www.ncbi.nlm.nih.gov/pubmed/11203539 | |
dc.description | Dimensional changes of resin/ionomer restoratives in aqueous and neutral media | en |
dc.description.abstract | 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. | en |
dc.language.iso | en | en |
dc.publisher | Elsevier Science Ltd | en |
dc.relation.ispartofseries | Dental Materials 16 (2000) 89-96; | |
dc.subject | Dental materials; Glass ionomer; Compomer; Dimensional change; Shrinkage; Hygroscopic expansion | en |
dc.title | Dimensional changes of resin/ionomer restoratives in aqueous and neutral media | en |
dc.type | Article | en |
local.publisher | University of Nairobi Dental School, Nairobi, Kenya | en |
local.publisher | 'The University of Manchester Dental School, Higher Cambridge Street, Mar/chester M I 5 6FJ-I, UK bThe | en |
local.publisher | The University of Ghana Dental School, Accra, Ghana | en |