Robert C. Caldwell

An Improved Amylase Assay

An improved amylase assay has been developed by modifying the method of Bernfeld (Advances Enzym 12:379-424, 1951), to increase accuracy and sensitivity. The method described here differs from that of Bernfeld as follows: (1) The color reagent contained 1 mg/ml of 3,5-dinitrosalicylic acid instead of 10 mg/ml. (2) Incubation was performed at 25 C instead of 20 C as a matter of convenience. (3) Samples for spectrophotometric observations were diluted 1: 10 instead of 1:5 to reduce the total amount of light energy absorbed. (4) Spectrophotometric readings were made at wavelength 470 mjA instead of 540 m~t because the absorbance peak of the reaction product occurs at 470 mg (Fig 1). REAGENTS EMPLOYED.-Enzyme.-Aqueous solutions of amylase (crystalline product of Aspergillus oryzeae with concentrations from 1 to 20 Ag/ml). Substrate.-One percent soluble starch solution (10 gm/i) in 0.02M sodium phosphate buffer, pH 6.9, containing 0.006M NaCl. The starch solution was heated to boiling and filtered using Whatman no. 1 filter paper. COLOR REAGENT.-One hundred milligrams

The Interaction of Salivary Proteins with Tooth Surface

Studies of the adsorption of human salivary proteins, in general, and the enzymes amylase, lysozyme, and neuraminidase, in particular, reveal that these proteins differ in their affinities for the surface of enamel. The enzymes studied retained their enzyme activity in the adsorbed state. Only amylase was desorbed by water; lysozyme was desorbed by its substrate; and all three enzymes, as well as most other adsorbed proteins, were desorbed by phosphate.

A Comparison of the Antimicrobial Activity of Disclosing Agents

A comparative study revealed that erythrosin (1.0% and 0.5%) inhibited a variety of microorganisms representative of the oral microflora in contrast to fast green (5.0% and 2.5%), which was essentially devoid of antimicrobial activity. These observations suggest that fast green may be preferable to erythrosin as a disclosing agent for quantitative studies of dental plaque.

The Effect of Neuraminidase on the Properties of Salivary Proteins

Neuraminidase rapidly cleaves sialic acid residues and increases the turbidity of human saliva. The isotherm for the adsorption of salivary proteins to hydroxyapatite is unchanged by preliminary treatment of the saliva or the hydroxyapatite with neuraminidase. The data suggest that neuraminidase does not alter the adsorption behavior of salivary proteins.

Development of Coatings for Application To Teeth

O NE approach to the prevention of dental caries is to form a protective coating on the 0 tooth surface. Long chain aliphatic amines have been used for this purpose (Green, R. W., and Walsh, J. P.: J. D. Res. 30: 218, 1951). The use of silicones in dental practice has been reported (Phatak, N., Savara, B. S., and Dement, J.: J. D. Res. 34: 788, 1955, and Savara, B. S., Phatak, N. K., and Dement, J. A.: J. D. Res. 37: 24, 1958), and many coating materials show promise for dental applications (McGregor, R. R., Silicones in Industry, New York, 1954, McGraw Hill). For a coating to be successful it should adhere to the enamel surface for a reasonable length of time and be resistant to wear, and to the action of salivary enzymes and their products. Coatings prepared from organic derivatives of silicone, phosphorus, and titanium were chosen as most likely to meet these requirements.