IADR Abstract Archives
Ion-Selective Electrode to Investigate Effect of Strontium on Hydroxyapatite Remineralisation
Objectives: The direct effect of strontium ions on demineralisation has been the subject of many in vitro studies, but its effects on remineralisation less so. The aim was to investigate the dose-response effect of strontium ions at increasing concentrations on remineralisation of previously demineralized hydroxyapatite discs using Ion-selective electrode (ISE) techniques.
Methods: Hydroxyapatite disc (n=6) (Plasma Biotal, UK) were immersed in a demineralisation solution (0.1M CH3COOH buffered to pH 4 using KOH) for 2 hours at 37°C. Ca2+ release was measured continuously via Ca2+ISE as a proxy for demineralisation.
The disc were then rinsed with deionized water and topically treated with 10% and 20% SrCl2 respectively for 1 minute using a micro-brush. Thereafter, the discs were immersed in remineralisation solution (2mM CaCl+1.2mm KH2PO4+150mM NaCl buffered to pH7 using KOH) for 10 hours at 37°C. Ca2+ ISE measurements continued to monitor for changes in Ca2+ concentration as a proxy for remineralisation.
Each experiment was repeated twice. For control, the disc was immersed in remineralisation solution without any topical treatment.
Results: During demineralisation, a constant release of calcium ion was detected by the ISE. During remineralisation, all discs showed a decrease in calcium ion concentration. Control discs showed a decrease in Ca2+ concentration of 0.0286mM/hr. However, 10% and 20% SrCl2 treated discs showed a drop in Ca2+ concentration of 0.01mM/hr and 0.015mM/hr respectively.
Conclusions: The results indicate that ISE can be used to measure the release and uptake of calcium ions during demineralisation and remineralisation. Increasing Sr2+ concentration inhibited the uptake of calcium ions during remineralisation, suggesting the direct effect of Sr2+ was to inhibit remineralisation.
Methods: Hydroxyapatite disc (n=6) (Plasma Biotal, UK) were immersed in a demineralisation solution (0.1M CH3COOH buffered to pH 4 using KOH) for 2 hours at 37°C. Ca2+ release was measured continuously via Ca2+ISE as a proxy for demineralisation.
The disc were then rinsed with deionized water and topically treated with 10% and 20% SrCl2 respectively for 1 minute using a micro-brush. Thereafter, the discs were immersed in remineralisation solution (2mM CaCl+1.2mm KH2PO4+150mM NaCl buffered to pH7 using KOH) for 10 hours at 37°C. Ca2+ ISE measurements continued to monitor for changes in Ca2+ concentration as a proxy for remineralisation.
Each experiment was repeated twice. For control, the disc was immersed in remineralisation solution without any topical treatment.
Results: During demineralisation, a constant release of calcium ion was detected by the ISE. During remineralisation, all discs showed a decrease in calcium ion concentration. Control discs showed a decrease in Ca2+ concentration of 0.0286mM/hr. However, 10% and 20% SrCl2 treated discs showed a drop in Ca2+ concentration of 0.01mM/hr and 0.015mM/hr respectively.
Conclusions: The results indicate that ISE can be used to measure the release and uptake of calcium ions during demineralisation and remineralisation. Increasing Sr2+ concentration inhibited the uptake of calcium ions during remineralisation, suggesting the direct effect of Sr2+ was to inhibit remineralisation.