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Biomedical subjects

J Van Houte

Publications and source records attributed to J Van Houte.

At least 19 recordsLinked to original sources
PubMed1991

Lack of correlation between food retention on the human dentition and consumer perception of food stickiness.

When dental health professionals advise that sticky foods be avoided, it is left to the consumer to choose correctly among different foods. In this study, comparisons were made among consumer ratings of stickiness of 21 commercially available foods and objective measurements of tooth retention of each of the foods. No correlation was found between the two, and neither the rates of clearance of food particles from the teeth nor the rates of clearance of food-derived sugars from the saliva correlated with ratings of food stickiness. Cookies, crackers, and potato chips were most retentive, whereas caramels, jelly beans, raisins, and milk chocolate bars were among those poorly retained. Clearance rates appeared to vary inversely with initial retention. However, chocolate-caramel bars exhibited high initial retention and a very rapid rate of clearance from the teeth. The findings show that consumers cannot accurately assess the retentiveness of foods and, thus, the advise simply to avoid sticky ones is inadequate.

Adhesiveness↗
PubMed1991

In vitro acidogenic potential and mutans streptococci of human smooth-surface plaque associated with initial caries lesions and sound enamel.

Samples of human dental plaque were pooled from several "white spot" smooth tooth surface areas as well as from several clinically-sound tooth surface areas in each of 12 caries-positive college students. Each of the two samples from each subject was used for the determination of: (1) pH-lowering potential in vitro involving dispersed plaque suspensions, excess glucose supply, and a 60-minute test, and (2) the proportions of mutans streptococci and lactobacilli. When all subjects were considered, plaques from "white spot" areas, as compared with samples from sound surface areas, were characterized by significantly higher proportions of mutans streptococci, a lower starting ("resting") pH, a faster rate of pH drop between pH 6.0 and 5.0, and a lower minimum pH of the suspension; the lactobacillus proportions were generally very low in both types of plaques. For individual subjects, however, the proportions of mutans streptococci in plaque associated with "white spot" areas showed a wide range (0.001-10.0%), and samples with high as well as low levels of these micro-organisms could exhibit a high rate of pH drop and a low pH minimum. This suggests that, besides mutans streptococci and lactobacilli, other bacteria capable of acidogenesis at a low pH may contribute to the high pH-lowering potential exhibited by many plaques.

Acids↗
PubMed1991

Mutans streptococci and non-mutans streptococci acidogenic at low pH, and in vitro acidogenic potential of dental plaque in two different areas of the human dentition.

Samples of human dental plaque were obtained from sound tooth surfaces in the lower anterior and upper posterior areas of each of 11 subjects with various degrees of caries experience. Both types of plaque were compared for: (1) their pH-lowering potential [pH at 10 and 60 min after sugar addition and the pH drop between 0 and 10 min (delta pH)] with an in vitro method involving dispersed plaque suspensions and excess glucose supply; (2) the proportions of mutans streptococci; and (3) the distribution of the predominant non-mutans streptococci according to their final pH in glucose broth. Compared with plaque from the lower anterior area, plaque from the upper posterior area exhibited a significantly higher pH-lowering potential, i.e., a lower pH at 10 and 60 min and a greater delta pH and significantly higher levels of mutans streptococci. The final pH values for the non-mutans streptococci exhibited a wide range from about 4.4 to over 5.0. The proportions of such organisms designated as capable of acidogenesis at low pH (final pH less than 4.6), whether expressed as a percentage of the total non-mutans streptococci or of the total plaque flora, were significantly increased in plaque from the upper posterior area. The proportions of non-mutans streptococci capable of acidogenesis at low pH in plaque from the upper posterior area were also significantly increased, with decreasing pH values at 10 and 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗
PubMed1990

Association of the microbial flora of dental plaque and saliva with human root-surface caries.

Dental plaque was obtained from one or two sound root surfaces of subjects with different degrees of root-surface caries experience. From subjects with root-surface caries, plaque samples were also obtained from either one incipient or one more advanced lesion. Proportions of the total flora were determined for total streptococci and different streptococcal species, total and different Actinomyces species, and lactobacilli. A sample of saliva was obtained from about one-third of the subjects for determination of the concentrations of mutans streptococci and lactobacilli. The main observations were: (1) Subjects without root-surface caries or restorations (group I), as compared with subjects with root-surface caries with or without restorations (group II), were characterized by having a lower prevalence and proportion of mutans streptococci and a higher prevalence and proportion of A. naeslundii in plaque on sound root surfaces; (2) subjects in group I also tended to have a lower salivary concentration of mutans streptococci and lactobacilli than subjects in group II; (3) dental plaque on sound surfaces in group II subjects contained a lower proportion of mutans streptococci than plaque associated with incipient or advanced lesions; and (4) the prevalence and proportion of lactobacilli in plaque associated with sound as well as carious root surfaces were very low. The data reinforce findings from other studies and indicate that, as for coronal caries, the plaque and saliva populations of mutans streptococci specifically are correlated positively with the presence of root-surface caries.

Actinomyces↗
PubMed1989

Increased pH-lowering ability of Streptococcus mutans cell masses associated with extracellular glucan-rich matrix material and the mechanisms involved.

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.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

Lactobacilli in human dental plaque and saliva.

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.

Adolescent↗
PubMed1977

Decreased oral colonization of Streptococcus mutans during aging of Sprague-Dawley rats.

The colonization by streptomycin-resistant Streptococcus mutans strains of the teeth of conventional and ex-germfree Sprague-Dawley rats of various ages fed either a high-sucrose or a high-glucose diet was studied. Bacterial colonization occurred with increasingly greater difficulty as the rats became older. This was observed in studies of the implantation of the test organism after oral inoculation with different cell numbers as well as its transmission between infected and uninfected rats. With rat fed sucrose diet, the effect of age could not be demonstrated until they were age 3 months or older; the results from rats fed a glucose diet suggest that changes may already have occurred early after weaning. Changes in susceptibility to colonization during aging manifested themselves as a decrease in the proportions of rats which became infected as well as lower population levels in infected rats. The possible mechanism(s) involved as well as the possible significance of the findings was discussed.

Aging↗
PubMed1977

Relationship between the populations of Streptococcus mutans in the mouth and feces of conventional Sprague-Dawley rats.

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 incisor 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.

Animals↗
PubMed1974

Relationship between the concentration of bacteria in saliva and the colonization of teeth in humans.

The relationship between the salivary concentration of bacteria and their number that can be recovered from tooth surfaces has been studied in 12 human subjects. The mean salivary concentration of naturally occurring Steptococcus mutans and lactobacilli, determined on selective media, was 3.7 x 10(5) and 3.8 x 10(5) colony-forming units (CFU) per ml, respectively. In subjects with salivary concentrations of S. mutans of about 10(4) CFU/ml or less or about 10(5) CFU/ml or less of lactobacilli, these organisms could not be isolated from cleaned teeth after 2 to 3 h of oral exposure. In experiments with streptomycin-labeled S. sanguis cells held in the mouth for 15 min, the minimal salivary concentration required for their recovery from the teeth was about 10(3) CFU/ml. Both S. mutans and lactobacilli were found to be highly localized on teeth. This evidence suggests that the concentrations of S. mutans and lactobacilli generally present in saliva are insufficient for the initiation of their firm attachment to relatively nonretentive tooth surfaces. The low efficiency of their intraoral spread, as suggested by their highly localized distribution on teeth, or of their transmission between subjects may be essentially due to the interrelated factors bacterial affinity and number of colony-forming units available for attachment.

Adult↗
PubMed1972

Ecology of human oral lactobacilli.

Lactobacilli were found in saliva, on teeth, and on the dorsum of the tongue, the vestibular mucosa, and the hard palate in humans. Their proportions in saliva, expressed as percentage of the anaerobically cultivable flora, were 10- to 100-fold higher than those on the tooth surface, but were comparable to those on the epithelial surfaces. The adherence of Lactobacillus casei and L. fermenti to oral surfaces was compared with that of streptomycin-labeled Streptococcus sanguis and S. salivarius by using in vitro-cultivated cells. The affinity of both Lactobacillus species for the tooth surface was very low compared with that of S. sanguis but was somewhat higher than that of S. salivarius. The lactobacilli and both Streptococcus species adhered to a similar extent to the dorsum of the tongue, whereas the affinity of the lactobacilli and S. salivarius for the vestibular mucosa was about one-half of that of S. sanguis. The results suggest that the affinity of lactobacilli for oral surfaces significantly influences their proportional distribution in the mouth. The relatively low affinity of lactobacilli for the tooth surface suggests that their recognized association with carious lesions and mechanical appliances under certain conditions may be due primarily to mechanical retention rather than unique growth conditions.

Cell Adhesion↗