This study describes the predominant cultivable microflora of three-week-old plaque samples obtained from human enamel sites, on the basis of microbial identification of over 9000 fresh isolates. Lower removable appliances, on which were mounted enamel sections and slabs, were worn by five young adult subjects under three experimental protocols. These were (1) 'normal' plaque conditions, (2) extra-oral sucrose applications nine times daily, and (3) inoculation of each subject's own mutans streptococci onto the enamel test sites and sucrose applications, as described above. With the exception of slightly higher proportions of Gram-negative bacilli associated with slab plaque following sucrose application, no significant differences in percentage or absolute counts of organisms were found between normal and sucrose plaques. The inoculation of mutans streptococci, combined with extra-oral sucrose applications, was associated with significantly higher percentages and absolute mean counts of both mutans streptococci and lactobacilli, and lower proportions of S. sanguis and S. oralis. Although the isolation frequency of mutans streptococci increased in all subjects and the overall mean proportion rose following inoculation, considerable inter-subject variation was seen in mean percentage counts of these organisms isolated from the three-week plaque samples.

A national consortium for dental primary care in Scotland has been formed as a result of integrated planning by groups involved in managing and delivering postgraduate dental education in Scotland, In 1998 a partnership was formed with representatives from the Scottish Council for Postgraduate Medical and Dental Education (SCPMDE) and the three Scottish dental institutions at Dundee, Edinburgh and Glasgow Universities. The principal aim of the Consortium is to promote evidence-based dental care through postgraduate education and research. The activities of the Consortium will provide a broadly based adjunct to current postgraduate provision with partner institutions contributing in different ways. Since its inception the Consortium has focused on two main areas:. 'Higher Training' for Primary Care.. Scottish Dental Practice Based Research Network.

The aim of this cross-sectional study was to investigate the clinical application of chairside tests for gingival crevicular fluid (GCF) aspartate aminotransferase (AST) levels and plaque BANA hydrolysis activity with the presence of the periodontal pathogens Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans. The study comprised 100 periodontitis sites (pocket depths greater than or equal to 4 mm, GI=3) from 10 patients with chronic adult periodontitis and 100 control sites (pocket depths <4 mm, GI<3) from 10 periodontally healthy patients comprising 55 healthy sites (pocket depths <4 mm, GI=0) and 45 gingivitis sites (pocket depths <4 mm, GI=1 or 2). The values for both BANA hydrolysis and AST levels were significantly higher in samples from periodontitis compared with gingivitis and healthy sites (p<0.001). A. actinomycetemcomitans was identified in 45% and P. gingivalis in 17% of periodontitis sites but neither pathogen was recovered from control sites and there was no significant correlation with the clinical parameters measured. There was no significant relationship between the presence of P. gingivalis and/or A. actinomycetemcomitans with BANA hydrolysis or AST levels. A significant correlation (p=0.0017) was observed between BANA hydrolysis and pocket depth and between AST hydrolysis and the GI (p=0.01). This study failed to demonstrate a positive association between chairside analysis of GCF metabolites for AST levels and/or BANA hydrolysis with P. gingivalis and A. actinomycetemcomitans. However, the GCF metabolites had a significant correlation with periodontally diseased sites in patients with chronic adult periodontitis and may help confirm clinical observations.

In this study, the major periodontal pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were detected in subgingival plaque samples from patients wit periodontal disease by polymerase chain reaction (PCR) and conventional culture methods. 170 prague samples from 43 patients were analysed, A. actinomycetemcomitans and P. gingivalis were each detected in 40 (24%) of samples by PCR, whereas conventional culture methods detected A. actinomycetemcomitans and P. gingivalis in 25 (15%) and 18 (11%) of samples, respectively. The proportion of patients carrying A. actinomycetemcomitans in at least 1 sampled periodontal site was 17/43 (40%) by PCR and 13/43 (30%) by culture; for P. gingivalis this was 12/43 (28%) by PCR and 9/43 (21%) by culture. Only 5 samples, from 3 patients, harboured both A. actinomycetemcomitans and P. gingivalis. It Is concluded that PCR is more accurate than conventional culture methods for identification of these periodontal pathogens in subgingival plaque samples and has a higher frequency of detection.

The aim of this study was to determine whether the Nd:YAG laser energies of 50 and 80 mJ at 10 pulses per second (pps) were capable of improving the clinical parameters associated with periodontal disease. These energy settings were chosen as previous work indicated that higher values would damage root surfaces and that 80 mJ had an in-vitro bactericidal effect. Eighty periodontally affected sites in teeth scheduled for extraction from 11 patients with adult periodontitis were randomly placed in one of the following four treatment groups: 1. laser treatment at 50 mJ, 10 pps for 3 minutes; 2. laser treatment at 80 mJ, 10 pps for 3 minutes; 3. scaling and 4. untreated control. Probing depth, bleeding on probing (BOP), plaque index, gingival index and gingival crevicular fluid (GCF) volume were measured at baseline and week 6. Baseline subgingival microbiological samples were collected, then repeated immediately after treatment and at week 6 to assess the total anaerobic colony forming units (CFU). Only the scaling group showed a significant reduction in pocket depth and BOP (P < 0.001). The microbial samples taken immediately after scaling and laser at 80 mJ and 10 pps treatments showed a significant reduction in total CFU compared with the baseline (P < 0.01), which was sustained only in the scaling group until week 6. Electron microscopy did not reveal any heat damage on the root surfaces. This study demonstrated that application of Nd:YAG laser pulses of 50 mJ and 80 mJ failed to improve the clinical and microbiological parameters of periodontal disease

OBJECTIVE:To obtain baseline information on the prevalence of oral problems and disease in institutionalized elderly in a Scottish hospital.DESIGN:A cross-sectional clinical investigation with complementary microbiological studies as appropriate.SUBJECTS AND METHODS:A cohort of 147 elderly in five long-term care wards; collection of demographic data; clinical examination to determine: i) the dental and denture status and associated lesions such as Candida-associated denture stomatitis and angular cheilitis, ii) oral mucosal disease; swabs as appropriate for microbiology.MAIN OUTCOME MEASURES:Dental status, root caries prevalence; denture status and hygiene, and associated disease; oral mucosal health.RESULTS:Median period of institutionalization of 147 patients was 15 months and 65% were aged 80 years or more; the majority were significantly mentally impaired; 52% wore complete dentures, 9% were partially dentate, 19% possessed partial or incomplete dentures; 20% were neither dentate nor had dentures. Of 80 patients who verbalised their complaints, 35% complained of dry mouth and 45% had denture-related problems, principally discomfort. The commonest oral finding was a coated tongue (56%); angular cheilitis was present in 25%, and Candida-associated denture stomatitis in 19%; none had oral ulcers.CONCLUSIONS:There was considerable unmet dental need with significant oral disease and poor levels of oral and denture hygiene in this target group; both dental and medical professionals should act in concert to deliver curative as well as preventative dental care for the elderly living in institutions to improve their quality of life.

Respiratory secretions provide an efficient method for protecting the large surface area of the lower respiratory tract. To determine whether lung secretions contribute to antifungal defences, murine bronchoalveolar lavage fluid (BLF) was tested for anti-candidal activity against 49 oral and vaginal isolates belonging to six different Candida species. The yeasts were incubated in unconcentrated, cell-free lavage fluid from Sprague-Dawley rats and then cultured quantitatively to measure residual viability. Experiments with C. albicans indicated that sensitivity to BLF increased in a time- and dose-dependent manner. This activity was heat-stable (56 degrees C) and consistent, irrespective of whether the BLF was derived from rats inoculated (orally) with candida or the uninoculated controls. Of the Candida spp. examined, C. albicans was the most susceptible followed by C. parapsilosis and C. tropicalis, whereas C. krusei, C. guilliermondii and C. glabrata were highly resistant. However, there were differences in susceptibility to BLF among different isolates within a given species. These results indicate that a heat-stable, soluble factor(s) in murine lavage fluid may suppress candidal colonisation of the lower respiratory tract and contribute to the defence mechanisms of the lungs.

The effect of 0.2% chlorhexidine gluconate on in vitro adhesion of Candida albicans to buccal epithelial cells (BEC) was studied in 12 healthy subjects and 12 patients with diabetes mellitus. Exposure of BEC for one minute with 0.2% chlorhexidine gluconate in vitro, or by rinsing the mouth in vivo, resulted in a significant reduction in candidal adhesion to BEC in both diabetic and non-diabetic subjects and between both groups. In addition to the known fungicidal effect of chlorhexidine, it also reduces Candida albicans adhesion to oral mucosal cells, a factor of importance in the establishment of candidal infection.

Whilst the importance of the mutans streptococci in the aetiology of dental caries is clear, a number of studies have described caries development in their absence. This investigation aimed to assess the cariogenic potential of Streptococcus gordonii, Strep. sanguis, Strep. vestibularis and Enterococcus faecalis in comparison with Strep. mutans and Strep. sobrinus, using a recently described in vitro model. In the presence of a 146 mM sucrose solution and powdered hydroxyapatite, each species was incubated for 5 h, after which acid anion production, calcium release and change in pH were measured. It was possible to assign each species to one of three groups, with E. faecalis, Strep. gordonii, Strep. sanguis exhibiting low, Strep. vestibularis intermediate, and Strep. mutans and Strep. sobrinus high in vitro cariogenic potential. This assay could be used as a screening test to assess the potential cariogenicity of a range of bacterial species.

Despite the numerous investigations on the adhesion of microorganisms to buccal epithelial cells, it is difficult to correlate different results, as disparate adherence values have been reported for a given organism. As one reason for this disparity may be the indigenous or natural bacterial populations on human buccal epithelial cells, the effect of the latter on subsequent microbial adherence in vitro was examined. There was a highly significant correlation between the degree of natural bacterial colonization on pooled buccal epithelial cells from 8 healthy donors and the adhesion of a single isolate each of Streptococcus mitis, Escherichia coli and Actinomyces naeslundii. However, no such relationship could be established for Candida albicans, Streptococcus milleri and another isolate of Streptococcus mitis. As in previous studies, variation in adherence values was found, both between samples from different donors, and from the same donor over time, but to a far lesser degree in pooled samples from different donors. These results imply that natural bacterial populations on buccal epithelial cells may affect the adhesion values derived from laboratory experimentation, and hence such data should be interpreted with caution.

Whilst the limited usefulness of caries activity tests based solely on counts of mutans streptococci is becoming increasingly apparent, to date, little attention has been paid to potential differences in the virulence of strains isolated from patients with varying disease experience. Recently an in vitro test was described involving the dissolution of bovine enamel, as a means of determining the cariogenic potential of S. mutans strains. The current study aimed to investigate this test further and to compare the dissolution of bovine enamel and different hydroxyapatite preparations as a possible means of differentiating strains of S. mutans with regard to cariogenicity. In the presence of a 5 per cent sucrose solution, six strains were incubated with either bovine enamel, solid hydroxyapatite, or powdered hydroxyapatite for 5, 24 or 48 h, following which acid anion production, calcium release and change in pH were measured. The results showed that incubation with the powdered hydroxyapatite for 5 h resulted in significant differences between strains which correlated with clinical disease experience. It is suggested that this improved assay could be used to investigate further the clinical significance of the relationship between in vitro cariogenic potential and caries experience.

The proteolytic and saccharolytic activity of 4 Candida species was investigated in batch cultures of pooled, human mixed saliva supplemented with glucose. All the Candida species investigated (Candida albicans, Candida tropicalis, Candida glabrata and Candida krusei) demonstrated a marked growth in saliva with a concomitant reduction in pH from about 7.5 to 3.3, within 72 h. Isotachophoretic analysis of the culture supernatant revealed the presence of a variety of acid anions of which pyruvate and acetate were the most abundant. Proteolysis of salivary components, evaluated by a biochemical assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was exhibited by all 4 Candida species, although there was inter-species variation. Despite the similarity in growth rates, C. tropicalis and C. krusei demonstrated greater proteolytic activity than C. albicans and C. glabrata. Neither candidal growth nor proteolysis was observed in glucose-free control saliva samples. In contrast, the degree of saccharolytic and proteolytic activity of a single isolate of C. albicans in glucose-supplemented parotid saliva appeared to be relatively weak compared with mixed saliva. As the oral cavity provides ideal low pH niches periodically supplemented with dietary carbohydrates, the acidic proteinases of Candida species may play a role in the pathogenesis of oral candidiasis.

The in vitro lysozyme susceptibility of three oral isolates of Candida albicans cultured in carbohydrate-supplemented media was studied. Lysozyme was shown to have a dose- and time-dependent killing effect on C. albicans isolates. Fungicidal activity persisted to varying degrees when yeast isolates were cultured in a variety of carbohydrates (glucose, galactose, sucrose, maltose, xylitol and lactose) before exposure to 20 micrograms/ml lysozyme. Sucrose and galactose grown yeasts exhibited increased resistance to lysozyme compared with (in decreasing order) those grown in glucose, maltose, xylitol or lactose. Further, the C. albicans isolates tested demonstrated strain variations in their susceptibility to lysozyme. These results suggest that dietary carbohydrate may play a role in modulating the yeast cell populations in the oral cavity by altering the fungal susceptibility to salivary lysozyme.

The in vitro sensitivity to lysozyme of twelve isolates of Candida (three isolates each of C. albicans, C. tropicalis, C. glabrata and C. krusei) pre-incubated in sucrose supplemented media, was determined by a growth inhibition assay. In general, C. albicans and C. tropicalis exhibited increased susceptibility to lysozyme as the sucrose concentration in the growth medium was reduced. Candida krusei demonstrated the reverse effect and C. glabrata isolates showed different trends. Although generally the Candida species examined were susceptible to lysozyme in the decreasing order of C. glabrata, C. albicans, C. tropicalis and C. krusei, differences in susceptibility were noted among different isolates within a given species. These results imply that salivary lysozyme and dietary carbohydrates may exert selective pressure on oral colonization by Candida species.

Specific immunoglobulin G (IgG), IgA and IgM antibody titres to Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were measured by enzyme-linked immunosorbent assay in serum and gingival crevicular fluid at 5 sites in each of 20 chronic periodontitis patients. Specific serum antibody titres correlated with mean gingival crevicular fluid titres. The 3 immunoglobulin subclass responses (IgA, IgG and IgM) to P. gingivalis correlated. A comparison of sites with probing depth < 4 mm and > or = 4 mm showed that the latter group had significantly lower gingival crevicular fluid IgG titres to P. gingivalis. Sites with a gingival index of 3 had significantly lower gingival crevicular fluid IgG titres to this organism than those with a gingival index of less than 3. These findings support the concept that the humoral immune response is protective, as chronic periodontitis patients with greater pocket depths and more gingival inflammation had paradoxically lower antibody titres to suspected periodontopathogens.

A modified Carlsson-Crittenden cup was used to collect three consecutive 0.5 ml samples of stimulated saliva from the parotid glands of 14 individuals with no known salivary disease and 14 patients with Sjogren's syndrome. Microbiological culture yielded bacteria from 30 of the 42 samples from healthy individuals and all 33 specimens obtained from patients with Sjogren's syndrome. The number and spectrum of bacterial species encountered in the two groups was similar, with a predominance of facultative alpha-haemolytic streptococci. The mean number of isolates (healthy group, 3.4; Sjogren's group, 3.7) and the mean viable concentration (healthy group, 6.9 x 10(3) c.f.u./ml, Sjogren's group, 4.2 x 10(3) c.fu./ml) was greater in the first sample and fell in subsequent samples in both groups. The only significant difference was a significantly greatest (P<0.05) mean number of isolates in the third 0.5 ml sample from patients with Sjogren's syndrome (2.6) compared to those in the healthy group (1.2). These results indicate that the duct of the parotid gland does have a microbial flora both in health and disease.