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Biomedical subjects

D A Geddes

Publications and source records attributed to D A Geddes.

At least 19 recordsLinked to original sources
PubMed1999

Human salivary sugar clearance after sugar rinses and intake of foodstuffs.

The aetiology of dental caries is in part related to the retention time of dietary carbohydrates in the oral cavity and their subsequent metabolism by the oral bacteria. Salivary clearance of fermentable carbohydrates from three different foodstuffs was examined in 5 subjects and analyses performed by high-performance anion-exchange chromatography with pulsed amperometric detection. The clearance of glucose, fructose, sucrose, maltose and sorbitol rinses was studied as well as that of chocolate bars, white bread and bananas. Of the sugar rinses studied, sucrose was removed from saliva most rapidly whilst appreciable levels of sorbitol remained even after 1 h. Clearance of residual carbohydrates from bananas and chocolate bars seemed marginally faster than in the case of bread, but sucrose levels still tended to fall more quickly than other carbohydrates studied. Surprisingly, carbohydrate residues from the three foods studied were still present in the mouth even 1 h after ingestion, which is longer than has hitherto been reported.

Bread↗
PubMed1996

Human salivary glucose analysis by high-performance ion-exchange chromatography and pulsed amperometric detection.

The aim of this project was to develop an analytical procedure with the required level of sensitivity for the determination of glucose concentrations in small volumes of unstimulated fasting whole saliva. The technique involves high-performance ion-exchange chromatography at high pH and pulsed amperometric detection. It has a high level of reproducibility, a sensitivity as low as 0.1 mumol/l and requires only 50 microliters samples (sensitivity = 0.002 pmol). Inhibition of glucose metabolism, by procedures such as collection into 0.1% (w/v) sodium fluoride, was shown to be essential if accurate results are to be obtained. Collection on to ice followed by storage at -20 degrees C was shown to be unsuitable and resulted in glucose loss by degradation. There were inter- and intraindividual variations in the glucose concentration in unstimulated mixed saliva (range; 0.02-0.4 mmol/l). The procedure can be used for the analysis of other salivary carbohydrates and for monitoring the clearance of dietary carbohydrates from the mouth.

Chromatography, Ion Exchange↗
PubMed1995

The effect of sucrose-containing chewing-gum use on in situ enamel lesion remineralization.

Two independent cross-over studies have now been carried out to evaluate the effect of a regime of chewing sucrose-containing gum on enamel lesion remineralization. The first study has been reported in detail elsewhere. This further study aimed to increase the data set with an additional 13 volunteers. Similar protocols were followed in both studies. Weighted averages from the two studies showed delta z values corresponding to 16.8% remineralization for the gum versus 11.6% remineralization for the control (p = 0.046, two-sided). A significant difference between test and control was evident for lesion body (p = 0.0004, two-sided) but not for surface zone (p = 0.32, two-sided).

Adult↗
PubMed1994

Non-attendance at periodontal clinics: forgetting and administrative failure.

Using a case-control design, non-attenders and attenders at a periodontal clinic were sent postal questionnaires in order to compare the sociodemographic characteristics of non-attenders and attenders. Non-attenders were also asked why they failed to attend. The main reason given was that they had forgotten about their appointment. Administrative error was the second most frequent category of response explaining non-attendance. Differences in sociodemographic characteristics between attenders and non-attenders did not appear to explain non-attendance, apart from car and telephone ownership. Time between notice of an appointment and the way patients received their appointments was associated with non-attendance. Non-attenders viewed their problem as less serious than attenders.

Adolescent↗
PubMed1994

Intra- and inter-individual differences in salivary sucrose clearance over time.

Salivary clearance of sugars influences acid production of dental plaque. The aim of the present study was to follow the clearance of sucrose over time. Ten subjects participated in five or six experiments each during a period of 20 months. The subjects rinsed with a 20% sucrose solution. Before the rinse and after 2, 5, 10 and 30 min a saliva sample was collected. The salivary sucrose concentration was determined by an enzymatic technique. As a measure of the clearance of sucrose in saliva, the area under the concentration versus time curve (AUC) was used. Analysis of variance revealed no differences with time in the intra-individual AUC. However, the differences in AUC among individuals were highly significant (p < 0.001). The results show that the clearance pattern of sucrose may be an individual property which is constant over long time periods.

Acids↗
PubMed1994

Diet patterns and caries.

Few dietary studies have been designed to investigate the effects of intake patterns of food items upon the environment of the teeth. This brief review considers evidence about the effects of choice, combination, and sequence of ingested food and drink upon the pH of human dental plaque in vivo. A series of three studies, which were designed to investigate some of the intra-oral biological events associated with cariogenicity during various eating patterns, are discussed. The principal findings show that if a "meal" includes an item which contains carbohydrate such as sucrose, glucose, or fructose which is rapidly fermented by the acidogenic microorganisms in dental plaque, there will be rapid acid production and the plaque pH will fall. However, other items eaten immediately before, during, or after the consumption of the sugary item can influence the plaque pH. If the non-sugary item stimulates saliva, it will have a pH-raising effect. The remineralizing potential may be enhanced if, for instance, calcium or fluoride is released from the food. However, if one sugary item is followed by another, the demineralizing potential may be enhanced. The results of these experiments are discussed in the context of our current understanding of the dynamics of the carious process. Recent preliminary experiments suggest that other factors, such as the individual subject's speed of consumption, may also affect the cariogenic potential of the oral environment.

Dental Caries↗
PubMed1993

Is salivary flow related to personality?

Studies conducted in the 1960s proposed that stimulated salivary flow was negatively correlated with the personality trait of introversion-extraversion such that introverted individuals were supposed to salivate more strongly to lemon-juice stimulation than were extraverts. The relationship was re-examined in the present study in light of more recent but inconsistent findings. A sample of 36 male and female volunteers showed no significant relationship between stimulated salivary flow and extraversion. Nor was flow related to State or Trait anxiety according to Spielberger's anxiety inventory, or to CNS activation as assessed by an objective electronic test. It was concluded that there was no evidence to relate stimulated salivary flow rates to personality in volunteers selected from a non-psychiatric population.

Adult↗
PubMed1992

Assessment of the cariogenic potential of Streptococcus mutans strains and its relationship to in vivo caries experience.

Strains of Streptococcus mutans isolated from the plaque of 6 subjects were studied using an in vitro model to determine whether differences in their cariogenic potential could be detected, and if so, whether the results correlated with the caries experience of the individuals. Each strain was incubated with a bovine enamel slab and 5% (w/v) sucrose for 24-h periods. The acidogenic potential was assessed by pH measurement and analysis of acid anion production. Microradiographic and microdensitometric assessment of the enamel, together with measurement of the change in calcium concentration of the reaction mixture were used to determine the demineralizing potential of each strain. Significant differences in cariogenic potential were found between some of the strains tested, and correlations were found between 3 of the test parameters and the decayed-missing-filled-surface score of the individuals. The results suggest that the caries experience of individuals may be related, to some extent, to the cariogenic potential of their S. mutans strains.

Acetates↗
PubMed1992

The effect of chewing gum use on in situ enamel lesion remineralization.

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization with the use of chewing gum. The first study involved a sorbitol-containing chewing gum, and the second, which had an identical protocol, tested a sucrose-containing chewing gum. In each study, 12 volunteers wore in situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice daily for two min with a 1100-ppm-F (NaF) dentifrice (control and test) and in the test phase chewed five sticks of gum per day for 20 min after meals and snacks. Microradiographs of the enamel lesions were made at baseline and at the end of the seven-week experimental period. In the sugar-free gum study, the weighted mean total mineral loss (delta z) difference [(wk7-wk0) x (-1)] was 788 vol.% min. x micron for the gum, corresponding to remineralization of 18.2%, vs. the control value of 526 vol.% min. x micron, 12.1% remineralization (p = 0.07). There were no significant differences for the surface-zone (p = 0.20) and lesion-body (p = 0.28) values. In the sucrose-containing gum study, the delta z difference was 743 vol.% min. x micron for the gum, corresponding to a remineralization of 18.3%, vs. the control value of 438 vol.% min. x micron, 10.8% remineralization (p = 0.08). The surface-zone values were not significantly different (p = 0.55). For the lesion body, however, the sucrose-containing gum value of 6.11 vol.% min. was significantly different (p = 0.01) from that of the control (2.81 vol.% min.).

Adult↗
PubMed1991

Teeth for the future.

The main dietary influences on teeth are, with the exception of ingested fluoride, local rather than systemic. The frequent use of carbohydrates which can be rapidly fermented by dental plaque micro-organisms is the major factor in dental decay. Sweetened and/or highly acidic soft drinks or medicines sweetened with sugars may damage the teeth. Similarly infant's comforters also have their dangers if they provide prolonged exposure of the teeth to cariogenic conditions. Although dental caries is primarily a disease of children many adults still develop new lesions and adults who have lost gingival tissue through periodontal disease may develop root surface caries. Pathological conditions of the oral mucosa can arise from nutritional disorders or inappropriate dietary habits. Health education is most effective when it carries a positive message so encouraging patients to eat the right kind of tasty snacks and to round off meals with sugar-free products or a modicum of cheese should in healthier eating without conflicting with general health guidelines.

Adult↗
PubMed1991

The areas of various surfaces in the human mouth from nine years to adulthood.

Surface area measurements of five regions of the oral cavity were made from study casts of 57 subjects with an age range from 9.3 to 19 years. While the longitudinal pattern of growth exhibited by the total of the five areas, when subgroups were compared, was characterized by a steady increase to around puberty (13 years), followed by a plateau, different areas showed different patterns of growth. Increase in the surface area of the teeth was associated with the eruption of the second and third molars, whereas the area of the buccal lingual mucosa continued to increase into adult life. The palate, buccal vestibular mucosa, and dorsum of the tongue demonstrated a typically skeletal pattern of growth, i.e., increase until puberty with a rapid cessation thereafter. The results of this study indicate the need for longitudinal data to further knowledge concerning growth of the oral cavity.

Adolescent↗
PubMed1990

Chewing gum and dental health--a review.

Recent evidence of the actions of chewing gum on plaque pH needs to be assessed against the background of other evidence, including clinical data. 'Sugar-free' gums are non-cariogenic and potentially beneficial in reversing early caries, while the potential cariogenicity of sucrose-sweetened gums can be modified by additives or selected patterns of use.

Chewing Gum↗
PubMed1990

The effect of salivary clearance of sucrose and fluoride on human dental plaque acidogenicity.

Ten subjects rinsed with a 20% (0.58 M) sucrose solution with or without 0.2% NaF (905 parts/10(6) F-) added in two separate experiments. Saliva and plaque were collected before rinsing and after 2, 5, 10 and 30 min. Sucrose and fluoride concentrations in saliva and acid anion and fluoride concentrations in plaque were analysed. There was a statistically significant and positive correlation between the concentration of sucrose in the saliva 2 min after the rinse and the subsequent concentrations of lactate in plaque at 10 and 30 min after the rinse with sucrose alone but not in the presence of fluoride. Salivary fluoride concentrations during 2-30 min after the sucrose rinse were significantly correlated with plaque fluoride concentrations during the same time. The addition of fluoride to the sucrose rinse significantly inhibited lactate production.

Acetates↗
PubMed1984

Instrumentation for measurement of dental plaque thickness in situ.

A commercial digital micrometer has been modified mechanically and electronically to allow the measurement, in situ, of the thickness of dental plaque. The device detects initial contact between a moving probe and the plaque, and measures subsequent probe displacement through to the tooth surface. Instrument accuracy is +/- 5 micron over a displacement range of 0-5 mm, with 1 micron resolution. In practice, after a short 'learning' phase, reliable clinical results can be obtained.

Biomedical Engineering↗
PubMed1983

Growth and acid production of Candida albicans in carbohydrate supplemented media.

Aerobic and anaerobic growth characteristics and acid production of a clinical and a reference laboratory strain of Candida albicans in 0.1 M, glucose or sucrose-supplemented batch cultures were examined for 72 h, at 37 degrees C. Both strains gave sigmoid growth curves, aerobically, and the pH dropped from 7.0 to 3.5 in 48 h. Candidal growth or acid production was not observed in submerged, anaerobic cultures. The specific growth rate (mu) of the clinical strain of Candida was significantly greater than the reference strain, in both sugar media. The major acidic component initiating and sustaining the pH drop appeared to be acetate, although formate, pyruvate and propionate were detected in varying proportions in glucose or sucrose cultures. These anionic, acidic metabolites of C. albicans, may play a role in the pathogenesis of mucosal candidoses such as chronic atrophic candidosis.

Acetates↗