IADR Abstract Archives
Hyaluronic Acid in Toothpaste Enhances the Remineralization Effect of Nano-hydroxyapatite
Objectives: Hyaluronic acid, more correctly known as hyaluronan (HY), is a non-sulfated glycosaminoglycan found in human tissues, chiefly as an extracellular matrix component and lubricant in the skin, cartilage and synovial fluid. Because of its use in dentifrice as a wetting agent, we conducted a study to determine whether it would affect, in a toothpaste, the functioning of the remineralizing ingredient nano-hydroxyapatite (nHAP).
Methods: Sample blocks cut from bovine tooth enamel were coated with nail varnish to leave just a 5x5mm window exposed, and immersed in demineralizing solution (0.1M sodium lactate, 0.1M lactic acid, 3.0mM CaCl2, 1.8mM KH2PO4, 1.0%CMC,pH4.8) for 4 days at 37°C, after which half of the window was further masked with nail varnish. Groups of 5 samples each were then immersed in a solution of nHAP dentifrice either without HY, or with the addition of different concentrations of HY (0.01%, 0.02% or 0.2% sodium hyaluronate respectively) for 12 days at 37°C. After removal of the nail varnish, blocks were sliced into 300-500μm-thick sections, polished with abrasive paper to a thickness of 100μm for observation by contact microradiogram (CMR-3, Softex), and the resulting radiographic images subjected to computer analysis to assess the degree of mineral loss and permit calculation of percentage remineralization.
Results: Compared with the percentage remineralization seen in the nHAP dentifrice group without addition of HY, each of the dentifrice groups with addition of HY (0.01%, 0.02% and 0.2% sodium hyaluronate) showed significantly higher remineralization (at 1.51, 1.52 and 1.47 times higher respectively, t-test, p<0.05). The degree of remineralization was not concentration-dependent.
Conclusions: Though further study is required to elucidate the mechanism, the addition of HY to the nHAP dentifrice, even at low concentration, significantly enhanced nHAP’s remineralizing effect.
Methods: Sample blocks cut from bovine tooth enamel were coated with nail varnish to leave just a 5x5mm window exposed, and immersed in demineralizing solution (0.1M sodium lactate, 0.1M lactic acid, 3.0mM CaCl2, 1.8mM KH2PO4, 1.0%CMC,pH4.8) for 4 days at 37°C, after which half of the window was further masked with nail varnish. Groups of 5 samples each were then immersed in a solution of nHAP dentifrice either without HY, or with the addition of different concentrations of HY (0.01%, 0.02% or 0.2% sodium hyaluronate respectively) for 12 days at 37°C. After removal of the nail varnish, blocks were sliced into 300-500μm-thick sections, polished with abrasive paper to a thickness of 100μm for observation by contact microradiogram (CMR-3, Softex), and the resulting radiographic images subjected to computer analysis to assess the degree of mineral loss and permit calculation of percentage remineralization.
Results: Compared with the percentage remineralization seen in the nHAP dentifrice group without addition of HY, each of the dentifrice groups with addition of HY (0.01%, 0.02% and 0.2% sodium hyaluronate) showed significantly higher remineralization (at 1.51, 1.52 and 1.47 times higher respectively, t-test, p<0.05). The degree of remineralization was not concentration-dependent.
Conclusions: Though further study is required to elucidate the mechanism, the addition of HY to the nHAP dentifrice, even at low concentration, significantly enhanced nHAP’s remineralizing effect.