Inhibition of Hydroxyapatite Dissolution by Ovalbumin as a Function of pH, Calcium Concentration, Protein Concentration and Acid Type

Abstract

Hydroxyapatite is the main constituent of the dental hard tissues, and in vivo its dissolution in acids leads to the pathological condition of dental erosion. Food proteins which inhibit hydroxyapatite dissolution may find application as erosion-reducing agents in food and drink products. The aim of this study was to investigate the egg protein ovalbumin as a potential inhibitor of hydroxyapatite dissolution in acidic solutions, with conditions representative of dental erosion. The dissolution rate of hydroxyapatite discs was measured in an acidic solution as a function of pH, calcium concentration, ovalbumin concentration and acid type. All experiments were performed in triplicate. 0.2% w/v ovalbumin significantly reduced the dissolution rate in citric acid by 50–75% over the pH range 2.80–4.00, and by 45–60% in solutions with calcium concentrations of up to 20 mM (p < 0.05). The effect was persistent for several rinses after the initial exposure to the protein. 0.02% w/v ovalbumin significantly reduced the dissolution of hydroxyapatite in citric acid by 30–55%. Ovalbumin did not, however, statistically significantly reduce the hydroxyapatite dissolution rate in malic or lactic acids. The effect is ascribed to adsorption and partial, reversible denaturation of ovalbumin on the hydroxyapatite surface. There may be some interaction between ovalbumin and the citrate ion which promotes the adsorption of protein in the presence of citric acid. Ovalbumin shows promise as a potential erosion-reducing additive to citrus-based drinks.

Comparação in Vitro do Efeito Erosivo de Refrigerantes Zero ou Light em Relação à Versão Regular

“…Outro mecanismo do adoçante poderia ser a deposição de uma película formada pelo aminoácido sobre a superfície do esmalte, constituindo uma barreira de difusão, diminuindo o contato do ácido com o esmalte. Estudos recentes têm mostrado in vitro, que a presença de diversos tipos de proteína, quando presentes com o agente erosivo, pode inibir os efeitos deletérios sobre a hidroxiapatita 22,23 . A concentração de aspartame na Coca-cola light é de 24 mg/100 mL e na Coca-cola zero é de 12 mg/100 mL , de acordo com informações do fabricante.…”

Development and evaluation of a low-erosive apple juice drink with Phosphoryl-Oligosaccharides of Calcium

“…Recently, additives derived from natural resources have gained more popularity as safer alternatives (e.g. CPP-ACP, green tea extract, ovalbumin, etc) [15][16][17][18] . In this view, the use of POs-Ca, which is derived from potato, bears an advantage in comparison to chemical food additives, and appears to be a practical means of formulating beverages with reduced dental erosivity for consumption by the public.…”

“…Current interest in prevention of dental erosion has led to an increasing attention to the ways in which erosive products might be potentially modified. Several methods are known for reducing the erosive potential of soft drink; such as adding calcium, phosphate, and some new additives derived from natural resources 8,[14][15][16][17][18] . The most common methods are increasing the pH by adding calcium-and/or phosphate-containing salts 8,14) .…”

In vitro evaluation of the erosive potential of viscosity-modified soft acidic drinks on enamel

“…The proteins might form a semi-permeable barrier, hindering transport of protons towards the hydroxyapatite crystal surface and/or calcium and phosphate ions away from the surface [8].…”