Periodontopathic micro-organisms in the rice rat (Oryzomys palustris).

The rice rat spontaneously develops periodontal disease, and this process can be accelerated if the animal is placed on a high sucrose diet. As the aetiological agent(s) is unknown, this study was undertaken to determine the micro-organisms associated with bone loss. Animals at weaning were placed on either a high sucrose diet or on regular rat chow and were sampled periodically for a variety of micro-organisms. Bacteroides spp., spirochetes, and Actinobacillus actinomycetemcomitans were not isolated from any animals, but fusiform-like organisms and Capnocytophaga spp. were isolated occasionally. An unidentified organism which had characteristics of both A. actinomycetemcomitans and Haemophilus aphrophilus was isolated from all animals at every sampling. Whether this organism is the primary aetiological agent of periodontal disease in the rice rat remains to be determined. Over the 12 week experimental period the animals on the high sucrose diet had significantly more exposed root surface than animals on regular rat chow.

Susceptibility of fibronectin to degradation by various gram-negative and gram-positive oral micro-organisms.

The degradative effects on tritiated human plasma fibronectin (FN) of proteases associated with twenty five Gram-negative (GN) and fifteen Gram-positive (GP) oral microbial isolates were examined. Ninety-two per cent of the GN and 20% of the GP isolates degraded the FN. In the GN group, the degradative effects were greatest for Bacteroides gingivalis and Treponema denticola, while in the GP group Streptococcus faecalis produced appreciable, and the two Lactobacillus casei isolates moderate and low, levels of FN degradation.

Diagnostic value of a coagglutination procedure using monoclonal antibodies to Bacteroides gingivalis.

A specific monoclonal antibody against Bacteroides gingivalis was bound to particles coated with protein A and evaluated for use in a coagglutination test. B. gingivalis was the only organism tested which gave a specific positive reaction with the CoA reagent. Subgingival plaque samples were collected from 217 patients diagnosed as having periodontitis. Organisms that gave biochemical reactions which indicated they were B. gingivalis were isolated from eleven of the 217 gingival pockets. These eleven strains were the only organisms which gave a positive reaction using the CoA test.

Production and characterization of monoclonal antibodies to Bacteroides gingivalis.

The rapid detection of Bacteroides gingivalis by immunological methods using monoclonal antibodies could greatly improve the diagnosis and prognosis of severe periodontal disease in adults. In this study, three distinct hybridomas were produced which secrete monoclonal antibodies to soluble and whole-cell antigen preparations of B. gingivalis. The BGII, V F9/2D hybridoma produced a murine antibody that can detect all of the B. gingivalis isolates studied while never cross-reacting with the other oral microbial antigens tested.

Salivary pH-rise activities in caries-free and caries-active naval recruits.

Kleinberg (1967) (Archs oral Biol. 12, 1457-1473) has observed that the incubation of a salivary sediment/supernatant mixture with a low concentration of glucose produces a pH drop followed by a pH rise. As this pH-rise effect could elevate oral pH in vivo, the degree of such activity could be directly related to caries resistance. The pH-rise of paraffin-stimulated whole saliva samples from 54 caries-free and 54 caries-active male naval recruits was compared in two assays. The first, conducted with sediment/supernatant/2.8 mM glucose mixtures, showed no significant differences for mean pH versus time profiles for 26 caries-free and 26 caries-active subjects. Concomitant assays, in which 3.33 mM arginine and water replaced the supernatants in the assay mixtures, showed slightly higher mean pH/time profiles, with higher minima for the caries-free subjects. These profile differences were statistically significant for the arginine-containing mixtures, a result attributed to different microbial distributions for the caries-free and caries-active sediments. The second assays were conducted on saliva supernatants from 28 caries-free and 28 caries-active subjects, employing a strain of Lactobacillus casei in place of salivary sediment in the assay system. No statistically significant differences were evident between the mean pH/time profiles for the two groups of subjects, although a significant positive correlation was observed between pH minimum and bicarbonate content of the samples. Thus no relationship of salivary pH-rise activity and caries experience were found.

A microbiological analysis of human early carious and non-carious fissures.

The fissure sampling technique consisted of removing the fissure using a bur in a high-speed handpiece with water spray and then suctioning the fissural contents and the water spray into a sterile sampling container. Sixty-eight teeth were sampled. Total bacterial counts, total streptococcal counts, and counts of Streptococcus mutans, Streptococcus sanguis, Streptococcus faecalis, Actinomyces viscosus, and lactobacilli were performed on the fissural samples. There was a four-fold increase in the total number of microorganisms recovered from carious (N = 48) compared to non-carious (N = 20) fissures. S. mutans was the only microorganism common to all carious fissures.

The performance of autoclaved high-speed dental handpieces.

High-speed dental handpieces, which are used so extensively in modern dental practice, may be a source of cross-contamination between patients. A standard autoclave procedure of 121 C for 15 minutes will sterilize the handpieces evaluated in this report. The performance in a standardized laboratory trial showed deterioration of speed in the simulated three-month period. Clinical evaluations for three months showed some minor mechanical problems. These dental handpieces should be used in conjunction with a formal daily and three-month maintenance program.

Dextranase-producing organisms in dental plaque from caries-free and caries-active naval recruits.

Dental plaque samples from caries-free and caries-active naval recruits were assayed for the prevalence of dextranase-producing organisms. These organisms were found in the plaque of all of the subjects. Mean percentages of dextranase-producing organisms with respect to total colony count for the 2 groups of subjects were not significantly different.

Differential utilization of proteins in saliva from caries-active and caries-free subjects as growth substrates by plaque-forming streptococci.

Mixed or parotid saliva from caries-active individuals consistently supported better growth of Streptococcus mutans (type c) than that from caries-free individuals. Electrophoretic studies revealed that certain proteins in caries-active salivas were susceptible to microbial attack, but similar proteins in caries-free salivas were refractory.

Immunization with dextransucrases, levansucrases, and glycosidic hydrolases from oral streptococci. II. Immunization with glucosyltransferases, fructosyltransferases, and glycosidic hydrolases from oral streptococci in monkeys.

The feasibility of immunizing monkeys with enzymes from oral streptococci in an attempt to reduce dental caries was investigated. Forty rhesus monkeys, Macaca mulatta, were used. Cariogenic streptococci, S mutans, were implanted into all the monkeys' mouths. There was no pathological effect resulting from immunization. Of the 40 animals, 30 retained the implanted flora throughout the experiment; the remaining 10 were reimplanted until the streptococci remained. In six months, gross carious lesions were evident with plaque. Inhibitiors present in the monkey sera after immunization inhibited glucosyltransferase, fructosyltransferase, and neuraminidase activities. It was presumed the inhibitors were antibodies. There was a reduction of 68.6% in the total carious lesions in the animals immunized intraorally with glucosyltransferase, 62.4% reduction in those injected with fructosyltransferase, and 57.4% reduction in total lesions in those immunized with glycosidic hydrolases after 19 months, as compared to the control group. There were no gross lesions apparent in the group immunized with glycosidic hydrolases. It appears that immunization with enzymes significantly reduces carries and is feasible in a primate model.

Gingivitis, bacterial plaque, and Streptococcus mutans in naval recruits from Saudi Arabia.

Gingivitis, dental caries, bacterial plaque, and the prevalence of Streptococcus mutans in plaque were studied in a group of 52 naval recruits from Saudi Arabia at the Naval Training Center, Great Lakes, Illinois. Gingivitis and bacterial plaque were found at higher levels in Arabian navy men, compared to American navy men, but with similar relationships. The dental caries experience of the Arabians was low, and the prevalence of S. mutans in the bacterial plaque had no clear relationship to gingival inflammation.

Relationship of Streptococcus mutans biotypes to dental caries prevalence in Saudi Arabian naval men.

A group of 217 Saudi Arabian naval recruits were examined clinically, radiographically, and microbiologically for the prevalence of Streptococcus mutans. Caries experience was considerably lower than in US recruits of comparable age and showed a significant positive correlation with the prevalence of S mutans in dental plaque samples. The distribution of S mutans biotypes and their relationship to dental caries in the Saudi Arabians were studied.

Biochemical study of the relationship of extracellular glucan to adherence and cariogenicity in Streptococcus mutans and an extracellular polysaccharide mutant.

A mutant of Streptococcus mutans, GS-5, which differed in extracellular polysaccharide (EPS) produced from sucrose, was used to study the role of EPS in the production of dental caries. The mutant proved to be identical to the parent strain in sugar fermentation, growth rate, and serotype. Strain GS-5 synthesized an EPS, which in electron micrographs appeared to be of fibrillar structure, whereas the mutant produced no fibrillar material but only a globular EPS. Analysis of the EPS revealed that about 30% of the glucose units in the GS-5 polymer carried (1-3)-like bonds either as branch points or as part of the linear backbone and that the mutant material contained only about 3% of these linkages. When grown in sucrose broth, the proportion of the mutant culture adherent to the glass vessel was dramatically less than that of the parent strain. Caries scores produced in conventional rats by the mutant were significantly lower than those obtained with the parent strain. Since the only difference discovered between strain GS-5 and the mutant was the inability of the mutant to synthesize either a fibrillar EPS or an EPS with more than about 3% (1-3)-like linkages, it was concluded that the fibrillar EPS of strain GS-5 contained about 30% (1-3)-like linkages and was necessary for adherence of the bacteria to surfaces and for production of dental caries in test animals.

Effect of multiple dental floss-SnF2 treatment on Streptococcus mutans in interproximal plaque.

Samples of dental plaque obtained from the interproximal tooth surfaces of seven young men showed considerable variation in the prevalence and anatomic site distribution of the potentially cariogenic microorganism S mutans. Multiple application of 10% SnF2 topical solution and saline solution delivered to interproximal test sites with dental floss were evaluated as short-term measures for eliminating S mutans from these surfaces. A greater overall reduction in the number of positive S mutans sites was observed for the SNF2-treated sites than the saline solution-treated sites. Long term studies are required to evaluate the effect of the treatments on the incidence of dental caries.

Distribution of Streptococcus mutans biotypes in five human populations.

The distribution of S mutans biotypes in five geographically separated human populations was investigated. Samples of dental plaque were obtained from recruits at the US Naval Training Center in Orlando, Fl (N=49) in San Diego, Calif (N=25), and in Great Lakes, Ill (N=194), and from a sample of Hawaiian school children (N=55) and Saudi Arabian Navy personnel (N-217). Cultural and biochemical methods were used for the isolation and identification of the five different biotypes of S mutans which correlate with Bratthall's serotypes a through e. Geographic differences in S mutans biotype distribution were most apparent when the Saudi Arabian sample was compared to the other four groups. Single and multiple biotypes were observed in each group. Multiple biotypes occurred most frequently in the Saudi Arabians. Biotypes a and b were rarely observed; c was the most common in each of the populations; and d and e were more prevalent in the Saudi Arabians than in the other groups. Because of the multifactorial nature of dental caries, caution should be exercised in the interpretation of population differences in caries experience that seem to be associated with differences in S mutans-type distribution.

Partial elimination of Streptococcus mutans from selected tooth surfaces after restoration of carious lesions and SnF2 prophylaxis.

This study examined the prevalence of Streptococcus mutans in dental plaque from carious and noncarious sites before and after routine dental treatment in five young men in the US Navy. S mutans was isolated in 96.3% of the samples from carious sites and in 63.3% of the samples from noncarious sites before treatment. After all carious lesions had been restored, the prevalence of S mutans was significantly reduced, but many of the carious and noncarious sites still had detectable levels of S mutans. A further reduction in S mutans was observed after conventional 8.9% stannous fluoride paste prophylaxis and 10% stannous fluoride topical application; however, in no instance was the organism completely eliminated. About 12 to 18 months after the initial examination, new carious lesions were seen in four men who were available for reexamination. Plaque samples of new lesions had high levels of S mutans. Therefore the restorations of lesions and the stannous fluoride prophylaxis treatments given under the conditions of the study were effective but incomplete measures for eliminating S mutans from the tooth surfaces of Navy personnel and were inadequate procedures for arresting the carious process.