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The effect of antibody to Streptococcus mutans in gingival crevicular fluid (GCF) on the recolonization of cleaned buccal root surface sites by indigenous mutans streptococci was studied. Seven subjects (mean age = 64 years) were selected from a population of 28 on the basis of the presence of appropriate sites with and without detectable immunoglobulin G (IgG) antibody in GCF to formalin-killed S. mutans and adequate levels of mutans streptococci in saliva available for root surface recolonization. Root surfaces exposed to GCF that did or did not contain antibody were then cleaned and sampled for residual plaque organisms (total cultivable flora and mutans streptococci) directly after cleaning (time 0) as well as 24 h later. One subject failed to recolonize at 24 h at any (antibody-positive or antibody-negative) experimental site. Fore each of the remaining 6 subjects, the mean levels of mutans streptococci (mean percentage of total flora) were lower at sites with IgG antibody to S. mutans in GCF than at antibody-negative sites in the same subject. In each of the 6 subjects, the site with the highest recolonization level was antibody-negative. Comparison based on intra-subject randomization of sites suggested diminished recolonization of mutans streptococci at sites with anitbody 24 h after cleaning. The results support the idea that antibody in GCF can modify the early colonization of gingival root surface areas by potentially cariogenic plaque bacteria such as mutans streptococci. [ABSTRACT FROM AUTHOR]

Streptococcus mutans strain IB-1600 was cultivated in Todd-Hewitt broth (THB) or THB supplemented with sucrose (S). Cell mass obtained from THB exhibited a high cell density and negligible glucan-rich extracellular matrix material (EMM), whereas cell mass from 2% S-supplemented THB exhibited widely-spaced cells separated by EMM. The pH-lowering potential of the different cell masses was studied in vivo with an intra-oral enamel demineralization test and rinsing with glucose solution, and in vitro with a model which permits vertical penetration of glucose through the cell mass and pH evaluation at different depths within the cell mass. In vivo, the pH profile of EMM-rich cell mass derived from 2% S-supplemented THB was characterized by a lower pH minimum and a slower return of the pH as compared with THB-derived cell mass. In vitro, an increase in cell mass EMM content was associated with a more rapid initiation and an increase in the rate of pH drop in the depth of the cell masses. Evaluation of the acidogenic potential of the cells in cell masses derived from THB and 2% S-supplemented THB with suspensions of dispersed cell mass and added glucose indicated no difference. The buffering capacity of cell mass derived from 2% S-supplemented THB within the pH range of 6.5-4.0 was greatly reduced as compared with that of THB-derived cell mass, due to the relatively low buffering capacity of EMM. The presence of EMM also appeared to enhance the porosity of the cell mass. Collectively, the data suggest that the presence of EMM increases the glucose supply, which leads to an increased rate of acid production by the cells and an enhanced pH-lowering ability of the cell mass. The possible implications of the findings with respect to the pH-lowering potential of human dental plaque are discussed. [ABSTRACT FROM AUTHOR]

The role of extracellular matrix material (EMM) synthesized from sucrose (S) by Streptococcus mutans IB-1600 in altering the demineralizing potential of artificial plaque was evaluated with an intra-oral enamel demineralization test (IEDT). The artificial plaque samples were prepared from cells cultivated in Todd-Hewitt broth (THB) supplemented with various S concentrations and by mixing THB-grown cells with increasing proportions of EMM (heat-killed THB + 2% S-cultivated cells). The samples were also evaluated for cell density (DNA content) and acidogenicity in vitro (pH-stat), as well as for in situ pH changes during a 45-minute intra-oral test following a 10% glucose rinse. An increase in the proportion of EMM relative to cell density was associated with an increase in enamel demineralization. This trend reversed when the ratio of cells to EMM was less than 1:19. Experiments involving strains of S. mitis, S. sanguis, and S. salivarius suggested a similar effect of EMM. The intra-oral pH data suggest that the presence of EMM may enhance demineralization by altering diffusion properties of plaque. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the reliability of the iodide permeability test when applied to the human dentition. Twenty-two subjects were seen once a week for three weeks. At each visit, consecutive iodide permeability measurements were obtained: four from the right central incisor and four from the left. Results of these trials were examined for the degree of variability from one replication to another within the same day, as well as for the variability from one week to the next. Within-day and between-week reliability of the test results was assessed by two indices: the Hoyt Index, which estimates the reliability of the average of the four replicate measurements per tooth, and the Intraclass correlation, which estimates the reliability of a single measurement. The results indicate that the iodide permeability test produces sufficiently replicable measurements for use in future clinical studies. [ABSTRACT FROM AUTHOR]

A newly-developed intra-oral enamel demineralization test was used to evaluate the effect of supplementation of a 10% sucrose solution with various components on enamel demineralization induced by the sucrose. Five human subjects wore a palatal prosthesis holding eight blocks of subsurface bovine enamel covered with a layer of S. mutans cells. The test involved rinsing with sucrose solution or with sucrose solution supplemented with 0.162 mol/l of different calcium salts or equivalent concentrations of Na-, K-, and Sr salts; rinsing was for one min at times zero and 45 min of the 90-minute test period. Ca-propionate, Ca-acetate, and Ca-levulinate completely inhibited sucrose-induced enamel demineralization; Ca-chloride, Ca-lactate, and Ca-ascorbate gave from 65-75%, and K-acetate, Nalactate, and Sr-lactate 39, 25, and 18% inhibition, respectively. Consideration of the anion dissociation constants and the Ca-anion association constants of the salts suggests that the observed inhibition is caused mainly by common ion effects and, to a lesser extent, by buffer effects. [ABSTRACT FROM AUTHOR]

Plaque from carious and sound tooth surfaces, as well as saliva from children with "nursing bottle caries," contained unusually high levels of Streptococcus mutans; the levels of Streptococcus sanguis in plaque on anterior teeth and Streptococcus salivarius in saliva were unusually low. Lactobacilli were detected in nearly all plaque samples. The findings are discussed in relation to the role of S. mutans and lactobacilli in the initiation of human dental caries and diet-plaque interactions. [ABSTRACT FROM AUTHOR]

Lactobacilli were isolated from about 50% of plaques from sound tooth surfaces of human subjects who had ingested fluoride (F) supplements since their births or subjects with negligible systemic fluoride exposure. In about 10% of these plaques, the proportions were 1% or higher of the total flora. Lactobacilli were not always isolated from caries-associated plaques. The mean salivary lactobacillus count of the F-supplement group was comparable to that generally reported for other groups of caries-active subjects with varying caries experience. The findings are discussed in relation to the role of lactobacilli in caries initiation and the anti-caries effect of fluoride supplementation. [ABSTRACT FROM AUTHOR]

Mass spectra of the three isomeric vinylimidazoles have been compared and the structures of the fragment ions [C3H4N2]+· and [C5H5N2]+ have been investigated by collisionally activated dissociation mass spectrometry. The greater part of the non-decomposing ions m/ z 68 from 2-vinylimidazole and from 2-imidazolecarboxylic acid methyl ester, and a minor part of this ion formed from the free acid, all have the same structure: the imidazole ring system, with hydrogens at both nitrogen atoms but none at C(2). An analogous structure, with an ethyl group at C(2), is proposed for the m/ z 93 ion from 2-vinylimidazole. [ABSTRACT FROM AUTHOR]

ions generated from a number of different presursors have been studied by high kinetie energy ion-molecule reations. It has been shown that at least four distinct stable species oeeur, of which acetonitrile and methyl isoeyanide retain their original structure. With imidazole or pyrazole as precursors, a mixture of open thain radical cations, not identical to the above species and probably interconvertible via the 1 H-azirine radocal cation, is formed. From butrynitrile, pyrrole, crotonitrile, allyl interconvertible via the and cyanocyopropane a fourth species, probably the vinylidenimine ion, is formed. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the prevalence and proportions of different streptococcal species among the streptococcal flora during infancy. A total of 60 oral samples were collected by oral swabbing of the buccal mucosa and alveolar ridges of 18 infants before tooth eruption and from buccal and lingual surfaces of teeth after tooth eruption. A total of 549 isolates on mitis salivarius agar were speciated, principally by recently revised biochemical criteria of Kilian et al. Streptococcus mitis biovar 1 predominated, both in prevalence (89%) and proportion of oral streptococci recovered in each sample (median = 87% of streptococcal flora). Streptococcus salivarius was also prevalent (94%) but generally represented a small percentage of the total streptococcal flora (median = 3%). Streptococcus oralis and Streptococcus anginosus strains were detected in approximately one third of predentate and dentate infants in the first year of life. Streptococcus sanguis strains were not detected before tooth eruption, but could be detected in &frac714; of the infants with teeth. Thus, S. mitis constitutes the major component of the initially colonizing streptococcal microbiota of the young infant. [ABSTRACT FROM AUTHOR]

The predominant flora of plaque developing on an area of about 1 sq cm. on the middle third of the buccal surface of the upper first molar of one individual was studied. Samples were taken at 5 and 15 min, 1, 2, 4 and 8 hr, and 1, 2, 4, 8 and 16 days; the tooth surface was cleaned prior to each period. Plaque samples were handled and cultured under anaerobic conditions utilizing various growth media. All isolates from blood agar plates in Brewer jars with 30 to 100 colonies were characterized. Streptococcus sanguis, the single-most predominant organism, and Actinomyces viscosus were consistently found. Streptococcus mills, Staphylococcus epidermidis, Actinomyces israelii, Peptostreptococcus sp. and Veillonella alcalescens were found at more than one time period. High proportions of "suspected pairs" (mixtures of 2 or more intimately-associated organisms), were regularly detected. Bacterial population changes with time were observed. Many isolates, particularly those present in plaques up to 8 hr, agglutinated in the presence of saliva. Less than half of the isolates, including Gram-positive saccharolytic rods, staphylococci and some S. sanguis strains, formed plaque in vitro on wires in the presence of sucrose or glucose. The data suggest that the nature of the early microflora observed is determined by bacterial attachment which may be influenced by, amongst others, salivary constituents. Subsequent cell multiplication leads to a large bacterial increase in which proportional changes may occur as a result of differences in bacterial growth. [ABSTRACT FROM AUTHOR]

The relationship between oral and fecal S mutans populations has been studied in rats fed high sucrose or glucose diet. All molar teeth were extracted either prior to or following oral challenge with strain 6715. In certain instances this procedure was supplemented with amputation of the incisors and disinfection of the remaining incisors surface area with iodine solution. The results suggest that in rats the colonization of S mutans on the teeth is required for its presence in the intestinal canal as well as the mouth. The significance of the observations has been discussed. [ABSTRACT FROM AUTHOR]

Firm attachment of S mutans cells to teeth by means of extracellular glucans synthesized from sucrose that lead to colonization in vivo may proceed via two mechanisms: (1) directly, via preformed glucans associated with the cell or the teeth or both, or (2) via new glucan synthesis by cells that are initially weakly attached, irrespective of the presence of cell- or tooth-surface-associated glucans. Data from experiments with conventional rats suggest that new glucan synthesis is the principal attachment mechanism. [ABSTRACT FROM AUTHOR]

Dietary sucrose, ranging in concentration from 1 to 56%, facilitated greater colonization of Streptococcus mutans on teeth than other carbohydrates. Satisfactory colonization in the absence of sucrose was also achieved, but required higher cell inoculums and appeared to be independent of coprophagy. The intake of a nonsucrose diet did not lead to the elimination of S mutans from the teeth. Other data suggest that S mutans cells have a certain affinity for the teeth in the absence of sucrose that may be of ecological significance, and that bacterial affinity is of importance even for colonization in fissures. [ABSTRACT FROM AUTHOR]

The relative losses of unlabelled vs. labelled HCN from the [M]+˙ and [M - 1]+ ions of a number of specifically labelled 1-methylimidazoles (I) and 1-methylpyrazoles (II) have been determined. Hydrogen randomisation in the molecular ions prior to fragmentation is insignificant. Expulsion of HCN follows two distinct pathways: elimination involving positions 2 and 3 (predominant in I) and elimination involving the methyl group and the nitrogen atom at position 1 (predominant in II). The molecular ions eject H˙ from the methyl groups to a high degree of specificity. In both cases some contribution by position 5 is observed. The resultant [M - 1]+ ions exhibit extensive, but incomplete hydrogen randomisation. Loss of HCN from these ions is consistent with intermediacy of ring-expanded ions, but notably in II a proportion of the HCN is generated from the group. A mechanism for this observation is presented. [ABSTRACT FROM AUTHOR]

The behaviour of a number of deuterated imidazoles upon electron-impact has been studied. Loss of H⋅ from the molecular ion occurs specifically at the 4(5)-position. Loss of HCN is less specific, the order being 2 > 4(5) ≫ 1. [ABSTRACT FROM AUTHOR]

The mass spectra of deuterated pyrazoles show that loss of H. and of HCN from the molecular ion occurs with a very high specificity from the 3(5)-position. For the two processes isotope effects and preference factors have been determined. Metastable ion decompositions involving the loss of HCN from the [M - H] -fragment indicate that the identity of the hydrogen atoms in this fragment is lost to a large extent. [ABSTRACT FROM AUTHOR]