R.S. Manly

Masticatory efficiency during the period of adjustment to dentures

Abstract Thirty-eight complete denture patients were given masticatory performance tests over a six-month period starting on the day of insertion. For the group as a whole there was no marked change in average masticatory efficiency, in the strokes needed to prepare food for swallowing, and in the particle size of food at the swallowing point. Apparently adjustment to dentures appears to be subjective rather than functional. Findings suggested that patients under 60 years of age who received dentures for the first time, especially if they used denture powder, would be most likely to show improvement in function during the six months following insertion of the dentures.

Metabolism of Levan by Oral Samples

Levan sucrase and hydrolase were present consistently in samples of dental plaque, but only the hydrolase was extractable with water. When plaque was incubated with sucrose, the levan content of the suspension reached a steady state that depended on the duration of incubation, sucrose concentration, and pH of the medium.

Retention of Carbohydrate from Sugar Solutions by Salivary Sediment

Several investigators have observed that momentary treatments of dental plaque or salivary sediment with sugar solutions will bring about an increase in glycolysis that persists for 2-6 hours. This observation is puzzling because it is difficult to explain how the small quantity of sugar that diffuses into sediment in 3 minutes is able to depress the pH level for 120 minutes. Sugar in the microbial film can be lost both through diffusion and through utilization by micro-organisms. Possibly the action persists because sugar is coverted to a less diffusible form, such as polysaccharide, mucoprotein, or phosphate esters. Snyder and others (J. D. Res., 34:368, 1955) have reported that sucrose can be converted to levan within 5 minutes by oral micro-organisms. This polymer is water-soluble but would be less diffusible than the parent structure, sucrose. The decrease in diffusion rate might serve to hold the substrate at a site which would make it available for glycolysis by the micro-organisms. This question was approached by means of anthrone tests on salivary sediment before and after treatment with sucrose solutions. One-half-ml. aliquots of homogenized saliva were centrifuged at 2400 r.p.m. for 20 minutes and the supernatant decanted. One aliquot was refrigerated; another was treated with 30 microliters of M/2 sucrose solution and then refrigerated; and the third and fourth aliquots were treated with the same volume and concentration of sucrose and allowed to incubate for 20 and 45 minutes, respectively. All samples were extracted three times with stirring and centrifugation, using 5 ml. of absolute alcohol to remove sucrose. Next 2 ml. of water was added, and the carbohydrate remaining in the sediment was determined by the anthrone modification used by Donald J. Beck (Masters thesis, University of Rochester, 1959). The investigation comprised 4 aliquots of pooled sediment with 10 or 11 replications. The mean per cent transmission of the control samples after reaction with anthrone was 23 + 3%, equivalent to 76 /ig. of sucrose. The samples treated with sucrose at 40 C. gave an average transmission of 21 ± 4%, equivalent to 80 Ag. of sucrose. Samples incubated at 370 C. for 20 and 45 minutes were 14 ± 4 and 8 ± 2 per cent transmission, respectively, corresponding to 100 and 166 A1g. In ten out of eleven comparisons the incubated samples showed a higher carbohydrate content than did the refrigerated sample. In all eleven comparisons the 45-minute sample showed more carbohydrate than did the 20-minute sample. These results indicate that salivary sediment has the capacity to convert sucrose into a substance which is alcohol-insoluble, at a rate approximating 10 per cent of the sediment weight per hour. This capacity is dependent on temperature, for it is less at room temperature (data not given) and practically lost at 40 C. Samples varied in their ability to retain carbohydrate. A single water extraction of the alcohol-extracted sediment removed much of the anthrone-positive material, indicating that it is water-soluble. We assume that micro-organisms have the capacity to store carbohydrate from sucrose solution in some non-diffusable form, such as polysaccharide, mucoprotein, or phosphate esters. Alcohol-insoluble carbohydrate has also been found in each of 13 samples of dental plaque obtained from the teeth of subjects who refrained from brushing for 3-4 days. The amounts present were uncertain, chiefly because of difficulties in measuring the quantity of dental plaque, but 5 of the samples appeared to approach 10 per cent carbohydate.

Inhibition of acid production of salivary sediment by ethers, esters, phenols, and alcohols.

SINCE 1952 an empirical program of testing in this laboratory has involved a wide variety of chemicals which are routinely screened for their ability to inhibit acid production by salivary sediment. The experimental methods have already been described.1 The first presentation concerned 350 substances containing a hydroxyl group which were selected from a group of 1,200 compounds tested.2 Later a report was made on 186 amines that sometimes contained other organic groups such as ether, ester, alcohol, or phenol.3 Additional substances have been tried since the previous report on alcohols, and now there are available for consideration 834 alcohols or phenols from a group of 2400 compounds which have been studied. The purpose of this presentation is to describe the active substances to be found among the simplest of organic structures, those compounds containing only carbon, hydrogen, and oxvgen, in whichl the oxvoen is in the form of ether, ester, alcohol, or phenol linkages.

The pH lEvels Attained by Compact Layers of Oral Microorganisms in Contact with Glucose Solutions

TT HAS often been observed that dental plaques can convert soluble carbol hydrate to acid rapidly enough to bring the pH of the plaque to a level that might cause solution of tooth enamel (Stralfors,1 Stephan,2 and Miller3). This pH decrease occurs locally within such dental deposits because of the action of a variety of bacillary and coccal organisms. Most studies of acid production rate of microorganisms have not employed high concentrations of organisms such as are present in dental plaques, and Stephan and Hemmens4 criticized the traditional methods of measuring acid production for this reason. Manly5 reported the construction of a recording pH meter which permits the study of pH attainment of saliva sediment under conditions of controlled temperature, buffer capacity, and carbohydrate concentration. One advantage of the apparatus lies in the fact that material to be tested can be fitted directly to the surface of a glass electrode while another electrode records the pH of the surrounding buffer solution within the cell. The differential between the 2 electrodes can then be interpreted as an index of rate of acid production. The purpose of this investigation was to study the pH attained at steady state by samples of dental plaques prepared at a standard thickness, placed in contact with a glass electrode, and immersed in a solution and maintained under controlled conditions of temperature, buffer capacity, and carbohydrate concentration. The pH values were to be compared with the pH attained by pure strains of microorganisms isolated from plaques and saliva and prepared in concentrated form by centrifuging. The knowledge obtained would disclose whether there are several organisms or combinations of organisms that are capable of producing a pH drop equivalent to that of dental plaques.

Glycolysis inhibitors among compounds containing aldehydes, ketones, and organic acids.

Abstract Nearly 800 compounds have been studied for ability to inhibit glycolysis of salivary sediment. These compounds possessed aldehyde, ketone and/or carboxyl groups as a part of the organic structure. The compounds were tested mainly at 1% concentration or half-saturation, in water or in 10% propylene glycol. The most active aldehydes were formaldehyde, succinaldehyde, pyruvic aldehyde, mucochloric acid, 5-nitrosalicylaldehyde and m -hydroxybenzaldehyde. Inhibition can be attributed to the aldehyde group of the first three compounds. Nearly all active aldehydes possessed a high degree of specificity. Among ketones there were nine organic structures which were capable of producing inhibition amounting to 50 per cent or more, but only for one substance, dioleyl ketone, could inhibition be attributed definitely to the keto group. Among others, such as pyruvic aldehyde, 2,3-butanedione-2-methoxime, Rose Bengal, 2-(dibutylamino)-ethylphenylketone and 2,4′-dihydroxybenzophenone, the inhibitory action was attributable to some group other than ketone. The three remaining inhibitory chemicals, verbenone, benzoquinone and 2,5-dimethyl para quinone possessed ketone as the sole functional group. Among the eight organic acids showing inhibitory activity, there was a high degree of specificity. One group, bromacetate, mucochlorate and alphabromopropionate, was related to iodoacetate, but all were less inhibitory. Sodium N-lauroylsarcosinate was inhibitory, but few similar structures were available for comparison. The 3,5-di-iodosalicylic acid probably owes its activity to the presence of the two halogens since loss of one of these produces an inactive structure, but 2-butyl-x-chlorophenoxyacetic has activity which is not possessed by closely related compounds. The two substances, 2- cyclo pentene-1-valeric acid and cyclo hexanebutyric acid are the only structures whose activity could apparently be attributed to the carboxyl group.

In-vivo determination of human enamel solution rate

Abstract A convenient method for determination of enamel solution rate in vivo has been developed. The two upper central incisors are etched simultaneously for one or two minutes by a packet containing cellophane film moistened with 1.5 m lactate buffer at pH 4.5. Calcium diffusing into the cellophane is transferred in vitro to a second cellophane film containing alizarin sulphonate and the calcium alizarin sulphonate formed is freed of excess reagent by a timed rinse. The cellophane is cemented to glass and the stable precipitate in the film is read densitometrically. Conditions of the test have been studied to optimize calcium fixation and rinse conditions, to verify stability of absorbance, to determine linearity and sensitivity, and to study the variables associated with the etch solution, the etch duration and the enamel surface conditions. The sensitivity of the method has been maximized in order to minimize the risk to experimental subjects.

Influence of microampere current flow on tooth enamel porosity

Abstract A reflectance method has been developed for measuring subsurface changes of enamel during slow decalcification. Sugar-treated dental plaque was able to cause such changes in vitro. The method was used to explore the influence of electrical potential on dental enamel during decalcification and remineralization. In both instances a current flow of 0.5 μA favoured decalcification when the enamel surface was positive.

Glycolysis Inhibitors among Organic Phosphorus Compounds

I. Di-substituted phosphate or phosphate: Di(2-ethyl hexyl) phosphate* ............... 1%, pg34t Dipropyl phosphate. S/2, pg85 Dibutyl phosphate ...... 1%, pg 86 Dodecyl phosphate...... S/2, pg 93 Di(2-ethyl hexyl) phosphite ................ S 2, pg 92 Dipropyl phosphate. 1 lt%, pg 96 II. Tri-substituted phosphate or phosphate: Tributyl phosphate*.. S 2, pg 51 Tris(2-ethyl hexyl) phosphate ................ S/2 94 Triethyl phosphate. 1% 1 114 Trioctyl phosphate ...... S/2, pg 129 Tributyl phosphate ...... S/2, pg 72 Tris(2-ethyl hexyl) phosphite ............... S/2, pg91 III. Monosubstituted phosphonates: Dodecyl* ..... S/2 33 Butyl .................. 1% 74 Octyl .. S/2, pg85 Decyl .. S/2, pg85 * Substances showing considerable inhibitory action. t Per cent recovery of original glycolysis rate as measured by pH change. pg = substances suspended in 10 per cent propylene glycol. S/2 = one-half saturated.

Enamel decalcification by natural dental plaque in sugar solutions

Abstract The edge-decalcification technique has been employed to observe the decalcification of enamel in vitro by dental plaque obtained in vivo . Four different factors were studied for their relative importance on penetration rate of enamel under attack by small quantities of natural dental plaque, treated with sugar solutions. The factors were the kind of sugar and its concentration, the concentration of buffer and the time of exposure of the plaque to a sugar solution. Concentration of buffer and the kind of sugar, whether sucrose or glucose, appeared to be unimportant under the conditions selected. The concentration of sugar was unimportant over the range of 1 molar to 0.1 molar and only a 20 per cent decrease in depth of penetration was found where the concentration of glucose was reduced to 10 millimolar. Plaque treated 30 min per day with sugar caused changes in the underlying enamel which was only slightly less than plaque treated for 5 hr per day, and only 45 per cent less than those treated 24 hr per day. The surprising finding was the relatively high values of enamel penetration that occurred when plaque had access to sugar only 2 per cent of the time.