IADR Abstract Archives
Adsorption of Volatile Sulfur Compounds by Nano-Hydroxyapatite for Halitosis Relief
Objectives: A major cause of halitosis is enzymatic destruction, in the oral cavity, of sulfur-containing amino acids in remnants of epithelial cells, bacteria and foods, giving rise to foul smelling volatile sulfur compound gases (VSCs), chiefly hydrogen sulfide (H2S) and methyl mercaptan (CH3SH). We tested the ability of nano-hydroxyapatite (nano-HAP), used widely in toothpaste, to adsorb VSCs as a means of halitosis relief.
Methods: Adsorption testing using headspace gas chromatography (HS-GC) was carried out on five toothpaste ingredients: nano-HAP; dicalcium phosphate, both dihydrate (DCPD) and anhydrate (DCPA); and green tea (GT) and Chinese sweet tea (CST) extracts, with activated carbon (AC) as positive control. For each test, 0.1g of ingredient, dispersed in 2ml of phosphate buffer (PB, pH7.5), was placed in a sealed vial, with a vial containing only PB as negative control. A solution of either CH3SH or H2S was then injected, and after 10min agitation in an incubator at 37 °C, the headspace gas in each vial was collected with a gas-tight syringe and injected into a gas chromatograph with flame photometric detector (GC-14B, Shimadzu Corporation) for measurement. The gas adsorption rate (%) was assessed in each case by comparing the amount of gas detected with that detected in the negative control vial.
Results: Adsorption ranking for CH3SH was AC and CST (100% each) > nano-HAP (89.5%) > GT (41.1%) > DCPA (6.1%) > DCPD (4.4%). For H2S, it was AC, CST and nano-HAP (100% each) > GT (74.1%) > DCPD (4.6%) > DCPA (0%).
Conclusions: Nano-HAP’s adsorption of CH3SH and H2S, which mediate halitosis, was comparable or equal to that of activated carbon and Chinese sweet tea extract, two known deodorizing agents. In addition to its remineralization and bacterial adsorption benefits, nano-HAP’s gas adsorption capability may offer new possibilities in the field of halitosis care.
Methods: Adsorption testing using headspace gas chromatography (HS-GC) was carried out on five toothpaste ingredients: nano-HAP; dicalcium phosphate, both dihydrate (DCPD) and anhydrate (DCPA); and green tea (GT) and Chinese sweet tea (CST) extracts, with activated carbon (AC) as positive control. For each test, 0.1g of ingredient, dispersed in 2ml of phosphate buffer (PB, pH7.5), was placed in a sealed vial, with a vial containing only PB as negative control. A solution of either CH3SH or H2S was then injected, and after 10min agitation in an incubator at 37 °C, the headspace gas in each vial was collected with a gas-tight syringe and injected into a gas chromatograph with flame photometric detector (GC-14B, Shimadzu Corporation) for measurement. The gas adsorption rate (%) was assessed in each case by comparing the amount of gas detected with that detected in the negative control vial.
Results: Adsorption ranking for CH3SH was AC and CST (100% each) > nano-HAP (89.5%) > GT (41.1%) > DCPA (6.1%) > DCPD (4.4%). For H2S, it was AC, CST and nano-HAP (100% each) > GT (74.1%) > DCPD (4.6%) > DCPA (0%).
Conclusions: Nano-HAP’s adsorption of CH3SH and H2S, which mediate halitosis, was comparable or equal to that of activated carbon and Chinese sweet tea extract, two known deodorizing agents. In addition to its remineralization and bacterial adsorption benefits, nano-HAP’s gas adsorption capability may offer new possibilities in the field of halitosis care.