Role of sucrose in plaque formation

Results are presented which support the concept that the bacterial enzyme glucosyltransferase (GTF) plays a crucial role in sucrose induced plaque formation. GTF was shown to adhere strongly to anionic, hydrophobic and polysaccharide solid materials, and to be able to produce glucans in the adsorbed state. It appears conceivable that GTF adsorb to teeth and produce glucans. Glucan chains on (he surface of the bacteria and glucans on the tooth surfaces interact (pack) and form a strong binding mechanism. The rigid α1,3 linked glucans produced by Streptococcus mutans are particularly suited for interaction of this kind. This mechanism could account for sucrose-induced binding of bacteria to enamel, pellicle covered enamel and preformed plaque. S. mutans would adhere particularly strongly to tooth surfaces in the presence of sucrose, according to this model.     

Fluoride acquisition on and in human enamel during topical application in vitro

Abstract – Fluoride acquisition during topical fluoride treatment was studied after different time intervals, at different concentrations and at different pH. The effects of pretreating the enamel with Ca⁺⁺, and of pre-etching were also tested. Four experimental groups of repeated measures design were established. Chemical assessments were made of the amounts of fluoride formed on (as alkali soluble fluoride, i.e., calcium fluoride) and in enamel (as firmly bound fluoride). The depositions on enamel were also demonstrated by SEM. The amounts of alkali soluble fluoride on enamel increased with time, concentration, pH-decrease and calcium availability. The time of exposure seemed to be the major factor. The amounts of fluoride deposited on enamel outranged by far (>70%) the amounts of fluoride acquired in the enamel. The formation of alkali soluble fluoride on enamel is probably limited by the availability of calcium ions. It is suggested that the fluoride on enamel may protect the enamel surface and serve as a reservoir of fluoride.     

Effect of antimicrobial mouthrinses on salivary microflora in healthy subjects

Abstract – The antibacterial effects of chlorhexidine and an oxygen releasing agent on the salivary microflora were evaluated in healthy subjects in two separate experiments: 1) mouthrinsing on a single occasion and 2) mouthrinsing two or four times a day for 1 wk. Both experiments were performed in a cross-over study, and each subject was randomly tested for both rinsing agents and a saline control. The total bacterial number and some selected bacterial genera were followed in saliva samples taken prior to (zero-samples) and on three occasions after the rinsing or rinsing period. The reduction of the total bacterial number by mouthrinsing two or four times a day for 1 wk with chlorhexidine was statistically significant and lasted for over 4 h. After rinsing with chlorhexidine on one single occasion the reduction of the microflora was statistically significant and of the same magnitude as after rinsing two or four times daily for 1 wk. Although statistically significant reduction was obtained, the significant biologic effect of antimicrobial agents may be questioned. The number of Strep, mutans was dramatically reduced with chlorhexidine in some subjects and this reduction lasted for over 1 wk. The oxygen releasing agent did not reduce salivary flora significantly when rinsing took place two or four times daily for 1 wk.     

Changes in cadaverine and putrescine metabolism in the mouse kidney induced to growth by an anabolic steroid

The formation of cadaverine and putrescine was studied in the kidneys of gonadectomized male mice stimulated to growth by nandrolone. an anbolic steroid with low androgenic activity. Administration of nandrolone resulted in an increased kidney weight and elevated activities of lysine and ornithine decarboxylase (assayed by measurement of the formation of ¹⁴CO₂ from the I-¹⁴C-labelled amino acids). The responses were dose and time dependent. The elevated enzyme activities were reflected by an increased endogenous kidney content of cadaverine and putrescine as well as in an increased urinary excretion of the diamines. Further, the kidney content and the urinary excretion of the polyamines sper-midine and spermine were elevated on nandrolone treatment. Fractionation of kidney extracts on pore gradient electrophoresis revealed an apparent molecular weight of about 95000 Daltons of the lysine decarboxylase as well as of the ornithine decarboxylase. On electrofocusing it was evident that both enzymes were present as more than one isoelectric form. However, the main form in both cases focused at a pH of about 5.0.     

Effect of xylitol on dental plaque in vivo during carbohydrate challenge

Abstract – Xylitol has previously been shown to inhibit acid production in vitro when glucose is used as energy source, and the present studies were carried out to investigate whether this effect was valid in vivo. A solution containing both xylitol and glucose was applied on sucrose—induced 4-day-old plaque in vivo. The xylitol added to the glucose solution inhibited the acid production in the plaque, measured as a drop in pH, compared to using glucose alone. A further reduction in acidogenicity was obtained when xylitol was used as a rinse for 1 hr continuously prior to the glucose challenge.     

Influence of glutardialdehyde on dentin demineralization in vitro and in vivo

Abstract – In this paper the results are presented on the action of glutardialdehyde (GDA) on the in vitro demineralization of human dentin and on the in vivo demineralization of dentin using the Ögaard orthodontic banding system. The results show that a 2 min application of a 2% GDA solution at pH = 3.6 reduces dentin demineralization in vitro and in vivo substantially. Microradiography shows a percentage reduction of lesion depth and mineral loss in vitro of 20 and 36%, respectively. After 2 wk in vivo demineralization the same percentage reductions are 60 and 44%, respectively. The mechanism of action of GDA on dentin is not certain yet. Presumably the in vitro action is due to surface cross-linking of the dentin matrix causing reduced Ca and phosphate transport out of the dentin. In vivo an additional effect may be a rather short term influence of GDA on plaque or on plaque accumulation. The results of this paper indicate that glutardialdehyde is an interesting agent to consider in the reduction of root caries.     

Adsorption of glucosyltransferase to saliva coated hydroxyapatite Possible mechanism for sucrose dependent bacterial colonization of teeth

Abstract – Glucosyltransferase (GTF) adsorbed to hydroxyapatite and to saliva coated hydroxyapatite in vitro. Several proteins which are known to be present in the "pellicle" which forms on hydroxyapatite when this mineral is exposed to whole saliva were shown to stimulate or inhibit GTF. It is suggested that these proteins may interact with GTF and cause binding of the enzyme to saliva coated hydroxyapatite. A model is suggested where GTF adsorbed to tooth surfaces may induce binding of microorganisms to tooth surfaces.     

Predominant indigenous oral bacteria isolated from infected root canals after varied times of closure.

Abstract – The pulps of 24 root canals, eight in each of three monkeys, were mechanically devitalized and exposed to the mouth flora for about 1 week and thereafter sealed. Microbiologic sampling and analysis was performed in 16 teeth (two of the monkeys) after 7 d of closure (initial samples). The teeth of the three monkeys represented observation times of 90, 180 and 1060 d. At the end of each observation period final samples were taken. Final sampling included samples from the main root canal, the dentin, and the apical region at the same sampling session. All microbiologic analyses were caried out quantitatively. Final root canal samples from the apical region showed a predominance of obligately anacrobic non-sporulating bacteria, in fact 85–98% of the bacterial cells were anaerobic. The most frequently found species were bacteriodes and Gram-positive anaerobic rods. alwer proportion of facultatively anaerobic bacteria was found. This was most pronounced for coliform rods in comparison with strains of B. melaninogenicus.     

One-Month versus Six-Month Therapy with Oral Anticoagulants after Symptomatic Deep Vein Thrombosis

ABSTRACT. The length of time for which deep vein thrombosis (DVT) should be treated with oral anticoagulants (OA) is controversial. In this study, 135 patients with symptomatic first period DVT (83 % with proximal DVT) were randomly allocated to OA for one or six months. The diagnosis of initial and recurrent DVT was confirmed by phlebography or plethysmography and thermography, or by a combination of all these methods. Pulmonary emboli were confirmed by lung scans or at autopsy. The patients were followed for at least one year. One patient had to discontinue OA prematurely because of haemorrhage. Seventeen patients left the project for other reasons, ten during and seven after therapy; in one of these DVT recurred. The recurrence rate during the first year was high (17% symptomatic recurrences) irrespective of whether OA had been given for one or six months.     

Acute Effects of Short-term Fasting on Blood Pressure,Circulating Noradrenaline and Efferent Sympathetic Nerve Activity

ABSTRACT Eleven moderately obese women, aged 46–62 years, with a body mass index of 29–34 and with borderline hypertension (repeated diastolic blood pressure >90 mmHg) fasted for 48 hours. Before the fast and after 48 hours of fasting, plasma noradrenaline, urinary noradrenaline, urine potassium, urine sodium and weight were measured. In six of the patients muscle nerve sympathetic activity was recorded from the peroneal nerve by tungsten micro-electrodes for 15 min each time. The efferent muscle sympathetic activity (MSA) was expressed as the number of bursts/min. The recordings were done before the fast and after 48 hours of fasting. We found significant decreases in body weight from 88.4±2.5 kg to 86.4±2.5 kg. Systolic blood pressure (BP) was reduced from 158±3 mmHg to 146±5 mmHg (p<0.001) and diastolic BP from 96±3 mmHg to 89±3 mmHg (p<0.01) during the fast. MSA was significantly increased from 42.0±5.5 bursts/min to 44.5±5.8 (n=6), while plasma and urine noradrenaline concentrations (n = 11) showed a non-significant tendency to increase. We conclude that the hypotensive response during the first days of extensive caloric reduction is not due to a decreased sympathetic activity. If anything, there may be weak increase of efferent sympathetic nerve activity and venous plasma levels of circulating noradrenaline. The mechanisms behind the acute hypotensive response to negative caloric balance are thus still unclear, but obviously different from long-term adaptation of the blood pressure.