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Biomedical subjects

F Gehring

Publications and source records attributed to F Gehring.

16 recordsLinked to original sources
PubMed1979

[Studies on cariogenicity of sugar substitutes in xerostomized rats].

A comparative study of the cariogenic characteristics of sugar substitutes Xylitol, L-sorbose, and Palatinit as well as saccharose and lactose was carried out in programmed feeding experiments with xerostomized and nonxerostomized rats. The xerostomized animals developed more caries with all substrates than did the nonxerostomized animals. The differences in the saccharose and the lactose groups however were significant. Compared with saccharose, it was confirmed with this method that the cariogenic characteristics of the sugar substitutes tested was low. Xylitol proved to be the least cariogenic.

Animals↗
PubMed1978

[Palatinite--a new sugar substitute and its caries prophylactic evaluation].

By means of programmed feeding experiments on rats, the caries-producing properties of a new sugar substitute Palat-nit were compared with those of other carbohydrates. The cariogenicity of Palatinit was significantly lower than that of sucrose and lactose and roughly comparable to that of L-sorbose. Reference strains of s. mutans are unable to produce extra-cellular polysaccharide or notable amounts of acid from Palatinit. The use of this substance as sugar substitute can be recommended for caries prophylaxis on the basis of these experiments.

Dental Caries↗
PubMed1977

[Immunological aspects of caries prophylaxis (author's transl)].

The bacteriological and immunological principles for the development of a vaccine against dental caries are presented in a short survey. The potential cariogenic Streptococcus mutans is the center of interest of this special area of research in caries prophylaxis because of its peculiar characteristics. In animal experiments, the protective effects of attempts to immunize with this cario-etiologically relevant species of streptococcus or its metabolic products differed and were sometimes contradictory. Also conditions in the human show no distinct connection between the dental status and the appearance of specific antibodies against Strept. mutans antigens. The pertinent literature cannot answer the question whether and when an effective vaccine against dental caries can be produced at the present time.

Animals↗
PubMed1977

[Contribution to the microbial catabolism of xylitol].

Five xylitol metabolizing streptococci strains from the oral cavity of the rat were examined with regard to their metabolic capacities for xylitol, sorbitol, mannitol, fructose, glucose and saccharose by means of the Warburg technique. The amounts metabolized were smallest with xylitol and sorbitol and considerably bigger with mannitol and fructose. By far the highest CO2 values were obtained with glucose, while saccharose was not metabolized at all. The experimental results confirm the weak metabolic capability of these organisms with regard to the sugar substitute xylitol.

Animals↗
PubMed1977

[Synthesis of extracellular polysaccharides by various forms of Streptococcus salivarius].

Streptococcus salivarius synthesizes extracellular polysaccharides (EPS) from saccharose under aerobic and anaerobic conditions. Under aerobic conditions primarily soluble fructanes are formed. There are no differences between the EPS synthesized by r- and s-forms under aerobic conditions; anaerobically the s-forms produce more EPS and more fructane than the r-forms. As compared to streptococcus mutans, the streptococcus salivarius produces considerably more fructane and insoluble glucane under the conditions used.

Aerobiosis↗
PubMed1977

[Cariogenic properties of various snacks in animal experiments].

In a conventional animal experiment with rats, the cariogenic properties of different snacks were studied and compared. Bananas caused the highest caries incidence, apples the lowest. In between ranged the caries values of two other tested sweets, wafers and gum drops. The differences in caries incidence were due to specific chemo-physical properties (stickiness, fat content). In addition to the evaluation of caries incidence, microbiological plaque examinations and sugar analyses of the tested substances were carried out.

Adhesiveness↗
PubMed1976

Turku sugar studies X. Occurrence of polysaccharide-forming streptococci and ability of the mixed plaque microbiota to ferment various carbohydrates.

Dental plaque samples collected from the subjects during the last 20 months of the 2 year trial were subjected to quantitative and qualitative analysis of the occurrence of S. mutans, S. sanguis, S. salivarius and the total growth on phenol red agar. Lyophilized plaque samples were homogenized and incubated on a sucrose containing medium under anaerobic conditions. In addition, the pH-values were measured after incubation of the mixed plaque flora in media containing 1% respectively xylitol(X), sorbitol, sucrose (S), fructose (F) or no carbohydrates. The results show a significantly lower incidence of S. mutans in the X-group relative to the S- and F-groups. The corresponding difference could not be observed between the S- and F-groups. The logarithmic means and standard deviations of the colony counts of S. sanguis, S. salivarius and total bacteria yielded no significant differences between the 3 sugar groups during the test period. Repeated pH-measurements, carried out at the 4, 12, 18 and 24 month phases, showed that, except in the presence of X, the mean values all fell below the pH-limit of 5.5. In the course of the study, no evidence was obtained of adaption of mutation enabling acidogenic decomposition of X. These findings emphasize the importance of low acidogenic potential in dental plaque, generally paralleled by a low incidence of dental caries.

Bacteriological Techniques↗
PubMed1976

Turku sugar studies XX. Microbiological findings and plaque index values in relation to 1-year use of xylitol chewing gum.

The aim was to study possible alterations in the microbial flora of plaque and saliva in relation to partial substitution of dietary sucrose with xylitol. The development of plaque index values was observed simultaneously. These observations were carried out during a 1-year clinical trial, the effects of sucrose (S) and xylitol (X) chewing gum on the incidence of dental caries being observed in 100 young adults. Paraffin-stimulated saliva samples were diluted stepwise and cultivated on Rogosa S.L. agar and Sabouraud agar aerobically. Lyophilized dental plaque samples were cultivated on phenol red agar under anaerobic and aerobic conditions. The pH-values were measured after incubating the mixed plaque flora for 1 and 7 days in the presence of various sugars. Both the arithmetic and geometric means of the total CFU values on Rogosa S.L. agar decreased in the S-group at the 6-month phase but returned to the starting level after one year, whereas in the X-group they decreased or remained on the starting level. At the 6-month phase the difference between the groups was significant (U-test, p = 0.0013) and almost significant (U-test, p = 0.0569) at the end of the study. No significant differences or changes could be seen between or within the groups on Sabouraud agar. The geometric mean values of S. sanguis and S. mutans as well as the total CFU values on phenol red agar decreased considerably in both the S- and X-groups, but no significant differences could be detected in any of the streptococcal counts between the groups. The pH of the carbohydrate-containing culture media infected with mixed dental plaque significantly decreased, with the exception of the xylitol containing ones in which the pH values were not lowered even after 7 days' incubation. A significant decrease in plaque formation in relation of chewing per se was demonstrable. The difference in the plaque index values equalling or exceeding 2 was significant between the S- and X-groups. No bacterial adaptation to utilize xylitol occurred during the trial.

Chewing Gum↗
PubMed1976

[The occurrence of Streptococcus mutans variants in man and laboratory animals].

Numerous S. mutans strains isolated from human dental plaque and from that of rats and hamsters were classified by a well-known biochemical differentiation system for the separation of the serotypes "a to e", and by seven different biotypes (I-VII). 182 S. mutans strains from human plaque were assigned to the following serotypes: "c" = 68%, "d" = 19%, and "b" and "e" = 4% each. Serotype "a" was not found at all and 10 strains could not be classified. Out of 60 S. mutans strains from the oral cavity of rats, 85% belonged to serotype "c", while in 25 strains from hamsters serotypes "e" and "d" predominated.

Animals↗
PubMed1976

[The cariogenicity of xylitol-decomposing bacteria in a gnotobiotic study].

In gnotobiotic tests in rats, two xylite-degrading streptococcal strains were tested with regard to their cariogenic properties. One strain was isolated from human dental plaque, the other from the oral cavity of rats. The test animals were associated with the test strains only, and received a saccharose, fructose or xylite chocolate diet for 12 weeks. At the end of the test, between 10(4) and 10(5) inoculated germs were found in the plaque of the test animals. The total caries incidence in the gnotobiotic rats was insignificant in all test groups, i.e. whether they were given saccharose, fructose or xylite chocolate diet, and in both test strains. As compared to the cariogenicity of an S. mutans reference strain, the cariogenic effect of the tested strains was without any practical importance.

Animals↗
PubMed1976

[Total bacterial count and the occurrence of Streptococcus mutans and Streptococcus sanguis in the air of various work areas].

In the various rooms of the Würzburg Dental School, the total germ contamination of the air and the incidence of S. mutans and S. sanguis strains was studied. The total number of organisms found as well as the number of the two polysaccharide-producing organisms varied considerably. The presence of the two streptococcal strains is not restricted to the air in dental surgeries. It is considered to be an additional risk that by far the highest incidence of the cariogenic S. mutans strain is found in the air of the rooms of the outpatient clinic for restorative dentistry and periodontology.

Air Microbiology↗
PubMed1975

[Effect of sugar-exchange fructose, sorbitol and xylitol on the incidence of caries anddental plaque flora of the rat].

The cariogenicity of fructose, sorbitol, and xylite in chocolate bars as against that of sucrose was tested by ad libitum and programmed feeding of rats. After both types of feeding, the sucrose-containing feed showed the strongest cariogenicity and the xylite-containing feed the weakest cariogenicity. At the end of the test, s.mutans bacteria were found most frequently in the dental plaques of the sucrose animals, while it was not possible to demonstrate the existence of such germs in the xylite animals.

Animals↗