Dental health

Milk proteins have been proposed to have potentially important roles in the preventionof dental caries by three principal mechanisms: (1) a topical mechanism substantiallyincreasing the level of calcium and phosphate in dental plaque; (2) bindingstrongly to hydroxyapatite and reducing the rate of dissolution of the mineral; (3)increasing dental plaque pH to retard demineralization of enamel (Harper et al. 1986,1987; Herod 1991; Reynolds 1987). A summary of the various research findings isgiven in Table 9.5. The primary CPPs with anticariogenic properties are derivedfrom as1-casein {as1-f(59–79)}, b-casein {b-csn-f(1–25)} and two peptides derivedfrom as2 casein {as2-f(1–21) and as2-f(46–70)}.The mechanism of dental caries formation is well understood. Cariogenic bacteria,including the mutans streptococci and lactobacilli, produce organic acids withindental plaque on fermentation of carbohydrates, which diffuse through the plaqueand into the porous subsurface enamel. The dissociation of these organic acids willlower pH, and in turn make hydroxyapatite (Ca10(PO4)6(OH)2) crystals soluble,leading to demineralization of the tooth enamel and dentin. Without remineralizationfrom the saliva, dental caries occur.CPPs contain a cluster of phosphoseryl residues that markedly increase thesolubility of calcium phosphate by forming colloidal casein–phosphopeptide amorphouscalcium–phosphate complexes (CPP–CaP); the result is an increase in thelevel of calcium phosphate in plaque facilitated by the CPPs acting as a reservoirof calcium phosphate. Studies have shown that the increase in calcium and phosphatecontent of plaque corresponds with the incorporation of casein into plaque (Reynolds1987). The sequestering and localization of amorphous calcium on the tooth surfaceacts to buffer the free calcium phosphate ions and maintain a state of super saturationwith respect to its close association with hydroxyapatite, thereby depressing enameldemineralization and enhancing the potential for remineralization. Once incorporatedinto plaque, as1-casein has been shown not only to act as a calcium phosphatereservoir, but also to buffer against bacterial acid production via a proton-acceptingaffinity at pH 7.0. These findings explain earlier reported observations by Weiss andBibby (1966) that the solubility of enamel could be reduced by more than 20% iftreated with milk. Similarly, Harper et al. (1986) have reported anticariogenic activityof different cheeses that were attributed to the casein and calcium phosphate contents.Clarifying these observations, more recent studies have reported that a CPP–CaPcomplex could significantly reduce caries activity in a dose-dependent manner, with0.1% CPP–CaP producing a 14% reduction and 1.0% CPP–CaP producing 55 and46% reductions in smooth-surface and fissure caries activity, respectively (Reynoldset al. 1995). These results were found to be equivalent to the use of 500 ppm fluorideand, moreover, to produce an additive anticariogenic effect when CPP–CaP andfluoride were combined in the treatment. The anticariogenic activity of the CPP–CaPwas not associated with a reduction in the level of total streptococci in plaque(Reynolds et al. 1995).The potential of minor proteins or peptides of milk associated with anticariogenicactivity has recently been investigated with proteose–peptone fractions (Grenby et al.2001). A major proportion of this fraction is believed to be derived from b-caseinand not from k-casein (e.g., glycoprotein). Proteose–peptones are water-solublecomponents present in low concentrations in milk and can contain phosphoserylresidues or other amino acids with ionic and neutral polar groups that may act tosequester calcium ions and thus protect against demineralization. Moreover, these same components may also form hydrogen bonds with the enamel surface as well as react with plaque matrix molecules or bacteria in facilitating anticariogenicproperties. From a dental standpoint, use of cheese as the last food in a meal will help toreduce caries. Even following substantial dilution of cheese with other meal componentsand heat treatment, cheese remains effective in significantly increasing plaque calcium concentration. The promotion of meals and snacks containing cheese as a means of caries prevention represents a positive approach to improved oral health (Moynihan et al. 1999).

Дата добавления: 2015-11-16