Biomedical subjects
Publications and source records attributed to D Beighton.
A range of selective media was used to culture the microbial flora of the dental plaque, tongue and palate, The subjects were five young men who smoked more than twenty cigarettes a day and four who did not smoke. Neisseriae were less numerous on the mucosal surfaces of the smokers.
OBJECTIVES: To compare the clinical effects of a fluoride-containing varnish (Fluor-Protector) in combination with a chlorhexidine-containing varnish (Cervitec) on existing root caries lesions in a group of frail elderly subjects. METHODS: A randomised double blind longitudinal study was utilised. Subjects (n = 102) were randomly allocated to a Test or Placebo group. All leathery and soft root caries lesions in all subjects were coated with Fluor-Protector while the lesions in the Test group were also coated with Cervitec and the lesions in the Placebo group were coated with a Placebo varnish. Treatments were repeated five times in a 12-month period. Clinical parameters associated with root caries, measurements of individual lesions and salivary levels of caries associated bacteria were made at intervals. RESULTS: The clinical severity of the lesions in the Test group did not change significantly during the 12-month study period. In the Placebo group the mean lesion width and lesion height and length of exposed root increased significantly and the lesions were significantly closer to the gingival margin. There were no significant changes in the salivary levels of caries-associated microorganisms after 12 months although, in both groups, there was initially a significant reduction in the salivary levels of mutans streptococci. CONCLUSIONS: The combination of Fluor-Protector and Cervitec is a useful, simple, quick and non-invasive method for the control and management of existing root caries lesions. The procedure could be performed by a dental hygienist and may be usefully applied in other high-risk groups including persons with Parkinson's disease, debilitating neuromuscular conditions and dry mouth from whatever cause.
A group of 20 students, harbouring >10(4) mutans streptococci per millilitre of saliva, was enrolled into the study. Models for sampling, reproducibly, the dental plaque present in specific sites (fissure and smooth surface) on the dentition were developed and validated. Withdrawal of normal oral hygiene procedures for only 1 day resulted in approximately 10-fold increases in the number of micro-organisms recovered from both sites. The effect of supplementing the subjects' diets with particular food items given 5 times per day [lemonade (5.8% w/v sugars, 250 ml), biscuits (digestive biscuits, 67.6% w/w carbohydrate of which 22% w/w was sugars and 45.6% w/w was starch), caramel toffees and sugar lumps] on the number of micro-organisms recovered and on the composition of the flora at both sites was determined. Dental plaque samples were taken after 5 days and it was found that supplementation of the diet with toffee and sugar lumps resulted in significantly more micro-organisms at both sampling sites. The supplementation of the diets with lemonade or biscuits did not significantly alter the numbers of micro-organisms recovered from either site. The percentage composition of the plaque samples from both dental sites remained relatively unaffected by oral hygiene although there were lower levels of mutans streptococci which might be related to the use of an antimicrobial toothpaste containing fluoride, triclosan and zinc citrate. This study suggests that the cariogenicity of certain sucrose-containing foods may, in part, be due to the enhancement of plaque accumulation in addition to other effects on the percentage composition of the plaque which may become manifest on prolonged usage of these dietary foodstuffs. These observations are consistent with dietary survey findings which often find consumption of confectionery related to caries experience or incidence.
A clinical study was carried out to assess relationship between the presence of approximal cavitation, the radiographic depth of the lesion, the site-specific gingival index and the level of infection of the dentine. Adult patients assessed as needing operative treatment and presenting with approximal lesions visible in the outer third of dentine on bite-wing radiographs were included in the study. Direct lesion depth measurements were recorded from the radiographs and the site-specific gingival index adjacent to the lesion was noted. The presence or absence of a cavity was recorded on an impression following tooth separation. During operative treatment samples of dentine were taken on entry to the lesions to ascertain the level of infection of the dentine. Visual evaluation of 54 successfully recorded impressions revealed that 85% were cavitated. Cavitated lesions were found to have higher site-specific gingival index scores compared to non-cavitated lesions (p = 0.03). The probability of cavitation was greater for lesions >0.5 mm from the enamel-dentine junction on bite-wing radiographs (p<0.01). The level of infection of the dentine was significantly higher for cavitated lesions than for non-cavitated lesions (p = 0.02). However, the non-cavitated lesions were still infected.
A randomized controlled clinical study was set up to assess caries removal following tunnel preparation (test group) and class II cavity preparation (control group). Sixty approximal lesions in adult posterior teeth, visible in the outer third of dentine on bite-wing radiographs, were referred for operative treatment. Initial dentine samples were taken on entry to the lesions in both groups. Following cavity preparation dentine samples were taken from beneath the marginal ridge in the tunnel group and at the cervical floor in both groups. Microbiological analysis was carried out to establish the level of infection of the dentine. The bacterial counts were high on entry to the lesions with a median log10 (CFU + 1) per sample of 3.07 (+/-1.24). Following cavity preparation bacterial counts at the cervical floor were significantly reduced in both amalgam and tunnel groups (p<0.00001). In the tunnel group, however, slightly increased bacterial counts were found beneath the marginal ridge compared to the cervical floor (p<0.01).
The predominant microflora recovered from infected dentine of 52 carious teeth from 14 children with nursing caries was determined using both selective and non-selective media for the isolation of specific genera and acidified media (pH 5.2) to isolate the predominant aciduric microorganisms, and compared with the microflora of sound enamel surfaces in caries-free children. Streptococcus mutans formed a significantly greater proportion of the lesion flora while Streptococcus oralis, Streptococcus sanguis and Streptococcus gordonii formed a significantly greater proportion of the plaque flora from sound tooth surfaces. The proportions of Actinomyces naeslundii and Actinomyces odontolyticus were significantly greater in the plaque samples than in the lesion samples. Actinomyces israelii formed 18.2% of the flora from the lesions, but was not isolated from the plaque samples. The proportions of Candida albicans, Lactobacillus spp. and Veillonella spp. were also significantly greater in the carious dentine than in the plaque samples. The most frequently isolated lactobacilli were Lactobacillus casei, Lactobacillus fermentum and Lactobacillus rhamnosus. The predominant aciduric flora was S. oralis, S. mutans and A. israelii and these taxa were also isolated from a similar proportion of the lesions at pH 7.0. Strains of S. mutans, L. casei, L. fermentum and L. rhamnosus isolated from individual carious teeth were genotyped using PCR-based methods. Each species was genotypically heterogeneous and different genotypes were recovered from different carious teeth in the same child. These data indicate that the microflora of lesions in the same child is microbiologically diverse and support a non-specific aetiology for nursing caries in which the physiological characteristics of the infecting flora, not its composition, is the major determinant underlying the disease process.
This study compared a laser fluorescence (LF) system (DIAGNOdent) with a visual caries scoring system for in vivo detection and diagnosis of occlusal caries under the conditions of an epidemiological study, in 132 mandibular and 38 maxillary first permanent molars in 170 children (mean age: 6.85 +/- 0.58 years). The teeth were cleaned and occlusal caries status in a selected investigation site recorded using both visual and LF systems. The LF readings were interpreted both according to the cut-off points recommended by the manufacturers and those based on laboratory research with histological validation. The percentage agreement of the LF and visual scoring system was better using the cut-off limits recommended by the manufacturer. Histological validation was not possible in this clinical study, but it appeared that either the LF method was overscoring some lesions or the visual method was underscoring them. Since the LF instrument cannot be expected to differentiate caries from hypomineralisation, it should probably be used as an adjunct to a clinical examination.
The hypotheses that raw fruits, whether whole or pulped, were cleared rapidly from the mouth and that the sugars in the whole and pulped fruits are fermented with equal efficiency to acids by the oral microflora were tested in this study. Groups of 7-9 adult subjects chewed 10 g of raw, whole or pulped fruit (apple, banana, orange, pear and pineapple) for 1 min and whole, unstimulated saliva samples were collected during the following 60-min interval. Each saliva sample was assayed for the concentrations of fruit-derived sugars (glucose, fructose and sucrose), fruit-derived acids (malic and citric) and acids which may be produced as a result of bacterial fermentation (acetic, lactic, formic and succinic). We found the fruit-derived sugars were rapidly cleared from the mouth (within 5 min). The major bacterially produced acids were lactic and succinic, which reached maximum concentrations in the 5-min sample. There was no significant difference, within a fruit, in the salivary levels of any of the sugars or acids between the raw whole or raw pulped forms. In light of these findings it seems unwise to assume that fruits may be consumed without consideration of their acidogenic potential.
The relationship between microflora, eruption status and caries status in the first permanent molar of young children was investigated in 177 children aged 6-7 years. A significantly greater proportion of fully erupted teeth were classified as sound and plaque-free compared to partially erupted teeth. Fully erupted teeth yielded greater numbers and proportions of mutans streptococci compared with significantly greater numbers and proportions of Actinomyces israelii in partially erupted teeth. Logistical regression analysis showed significant associations between white spot lesions in partially erupted teeth and increased numbers of Streptococcus oralis, mutans streptococci and Streptococcus salivarius whereas the presence of Actinomyces naeslundii was associated with health. Significantly greater numbers and proportions of S. oralis and S. salivarius were isolated from partially erupted teeth with white spot lesions whereas Streptococcus mutans was isolated in significantly greater numbers and proportions from fully erupted molars with white spots. This study suggests that organisms other than mutans streptococci are associated with caries development in erupting permanent molar teeth.
To compare the effects of fluoride-containing and fluoride-free toothpaste on plaque microflora, 15 subjects were enrolled in a double-blind crossover trial. All subjects used a fluoride toothpaste for 7 days before the trial started. Then, 4 interproximal sites per subject were professionally cleaned and subjects used one of the toothpastes for 5 days. On the 5th day plaque was collected from 2 sites, 12 and 6 h after toothpaste use. There was no difference between the groups in the numbers or proportions of aciduric bacteria (recovered at pH 4.8 or 5.2), or of yeasts, neisseriae, lactobacilli or streptococci (total or individual species, including Streptococcus mutans). However, the numbers and proportions of Gram-positive pleomorphic rods, primarily Actinomyces naeslundii, increased in 6-hour samples from subjects using fluoride toothpaste. The data suggest that the anti-caries effect of fluoride toothpaste is not mediated primarily through effects on the plaque microflora, although effects on plaque physiology could be important.
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A supplemented, infusion-based medium that supports the growth of most oral Actinomycetaceae is described. The inclusion of Naf and colistin sulfate enabled actinomyces to be isolated from dental plaque in the presence of few other oral microorganisms.
The pattern and severity of root caries in a selected older population, living in the community and attending a general dental practice in Bexhill, East Sussex, England, is reported. A total of 146 patients were examined to determine the relationship among removable partial dentures, their design, and root caries. Of those patients, 57% wore removable dentures and had a higher prevalence of exposed root surfaces and root caries, particularly on abutment teeth. In addition, root caries lesions on abutment surfaces were found to be larger and more active than those on nonabutment surfaces.