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Biomedical subjects

F Gehring

Publications and source records attributed to F Gehring.

At least 55 records · Page 3Linked to original sources
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↗