A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
The physics of water sorption by resin-modified glass-ionomer dental cements
The water-sorption characteristics of two commercial resin-modified glass-ionomer dental cements (Baseline VLC, ex. Detrey Dentsply, and Vitremer lining cement, ex. 3M Dental Products) have been studied in more detail than previously. Water sorption in both cements proved to be rapid, reaching equilibrium at approximately 48 hours for Baseline VLC and at approximately 10 days for Vitremer. Over the first 8 hours or so, absorption was shown to follow Fick's law, with a diffusion coefficient of 1.56 x 10-7 cm2s-1 for Baseline VLC (cured for 20 seconds) and 5.09 x 10-7 cm2s-1 for Vitremer (also cured for 20 seconds). As expected, sorption of water was found to be faster in specimens cured for shorter cure times and slower for those cured for longer times. In the presence of sodium chloride, both at 0,9 % and at 1 M, diffusion coefficients were significantly greater than in pure water, but did not vary significantly with sodium chloride concentration, being approximately 3,3 x 10-7 cm2s-1 for Baseline VLC and 8,0 x 10-7 cm2s-1 for Vitremer. This is attributed to conformational changes in hydrophilic segments of the polymer on absorption of aqueous sodium chloride in which the molecules form more compact coils than in the presence of pure water. They thus create a microstructure that is more permeable to water. Sorption in salt solutions became non-Fickian much sooner than in pure water, i.e. at 3 - 4 hours for both cements. This is probably due to concentration changes of salt within the cement, suggesting that these materials possess a degree of permselectivity. Finally, equilibrium water uptakes varied with salt concentration, being least in 1 M NaCl, which reflects the different chemical potentials of water in the various storage media.
The physics of water sorption by resin-modified glass-ionomer dental cements
The water-sorption characteristics of two commercial resin-modified glass-ionomer dental cements (Baseline VLC, ex. Detrey Dentsply, and Vitremer lining cement, ex. 3M Dental Products) have been studied in more detail than previously. Water sorption in both cements proved to be rapid, reaching equilibrium at approximately 48 hours for Baseline VLC and at approximately 10 days for Vitremer. Over the first 8 hours or so, absorption was shown to follow Fick's law, with a diffusion coefficient of 1.56 x 10-7 cm2s-1 for Baseline VLC (cured for 20 seconds) and 5.09 x 10-7 cm2s-1 for Vitremer (also cured for 20 seconds). As expected, sorption of water was found to be faster in specimens cured for shorter cure times and slower for those cured for longer times. In the presence of sodium chloride, both at 0,9 % and at 1 M, diffusion coefficients were significantly greater than in pure water, but did not vary significantly with sodium chloride concentration, being approximately 3,3 x 10-7 cm2s-1 for Baseline VLC and 8,0 x 10-7 cm2s-1 for Vitremer. This is attributed to conformational changes in hydrophilic segments of the polymer on absorption of aqueous sodium chloride in which the molecules form more compact coils than in the presence of pure water. They thus create a microstructure that is more permeable to water. Sorption in salt solutions became non-Fickian much sooner than in pure water, i.e. at 3 - 4 hours for both cements. This is probably due to concentration changes of salt within the cement, suggesting that these materials possess a degree of permselectivity. Finally, equilibrium water uptakes varied with salt concentration, being least in 1 M NaCl, which reflects the different chemical potentials of water in the various storage media.
The physics of water sorption by resin-modified glass-ionomer dental cements
Die Physik der Wassersorption bei harzmodifizierten Glasionomerzementen für dentale Anwendungen
Nicholson, J.W. (author)
Journal of Materials Science - Materials in Medicine ; 8 ; 691-695
1997
5 Seiten, 4 Bilder, 4 Tabellen, 17 Quellen
Article (Journal)
English
Glass ionomer dental cements: update
| British Library Online Contents | 2010
Bond strength of experimental cyanoacrylate-modified dental glass ionomer cements
| British Library Online Contents | 2010
Long-term flexural strengths of resin-modified glass-ionomer cements
| Tema Archive | 1998
A study of phosphate ion release from glass-ionomer dental cements
| British Library Online Contents | 2014
NMR Microscopy of Glass-Ionomer Cements
| British Library Conference Proceedings | 1998