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Biomedical subjects

L Netuschil

Publications and source records attributed to L Netuschil.

At least 37 records · Page 2Linked to original sources
PubMed1995

Microbial vitality of supragingival dental plaque during initial stages of experimental gingivitis in humans.

Although vital plaque micro-organisms are part of the natural ecosystem in the oral cavity they are also the key factor in the development of diseases induced by the human dental plaque. In a previous study (9) the portion of vital bacteria related to the total number of plaque micro-organisms (i.e. the microbial vitality) appeared low in small plaque samples. The objective of this investigation was to determine the exact relationship of microbial vitality and age of supragingival plaque during the early phases of human dental plaque formation. Between intervals of optimal oral hygiene, thirteen participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was completely sampled from a defined area situated on the vestibular surface of the teeth 13, 14, 15, 23, 24 and 25. The pooled plaque from these areas was immediately processed. Total bacterial counts (BC) as enumerated by darkfield microscopy, and colony-forming units (CFU) were recorded. The microbial vitality was calculated indirectly as plating efficiency (PE = CFU per BC) and directly assessed using a vital fluorescence (VF) technique. In the 1 h old plaque samples the median values of PE and VF were 29% and 18%, respectively. Thereafter, the microbial vitality increased significantly with plaque age. The 24 h old plaque samples yielded values of 77% (PE) and 62% (VF). It was concluded that the microbial vitality of the early dental plaque investigated was considerably lower compared to that of a more mature plaque.

Adult↗
PubMed1994

Repeated subgingival oxygen irrigations in untreated periodontal patients.

The aim of this study was to assess the effect of repeated subgingival oxygen irrigations in previously untreated deep periodontal pockets. 112 pockets > or = 4 mm were selected in 14 subjects. Probing attachment level and bleeding on probing were recorded, as well as the presence of disease-associated micro-organisms within the pocket. Subsequently, the pockets were irrigated with gaseous oxygen 1 x a week during a continuous 8-week period. Irrigations with nitrogen served as control. The re-evaluation of all clinical and microbiological parameters at the end of study revealed that repeated oxygen insufflations resulted in a significant clinical improvement of the periodontal baseline conditions superior to the one found in the control.

Adult↗
PubMed1994

Effect of chlorhexidine-containing varnish (Cervitec) on microbial vitality and accumulation of supragingival dental plaque in humans.

The effect on local plaque formation of a varnish containing 1% chlorhexidine and 1% thymol (Cervitec) was evaluated. Ten volunteers with clinically healthy oral conditions were asked to refrain from any kind of oral hygiene measures for three periods of three days. Undisturbed plaque formation was recorded during the first experimental period. At the beginning of the second period, the varnish was applied to six vestibular enamel surfaces and removed after 1 h. The third experimental period was initiated 12 weeks after varnish application to assess a potential long-term effect. During each period of plaque formation, samples were collected from the vestibular surfaces after 24 h (from teeth 15/25), after 48 h (from teeth 14/24) and after 72 h (from teeth 13/23), respectively, and evaluated for total microscopic bacterial counts (BC) and colony forming units (CFU). Microbial vitality was assessed by the plating efficiency [PE = (CFU/BC) x 100] and directly by a vital fluorescence (VF) technique. VF of 48- and 72-hour plaque was significantly reduced after Cervitec application. An inhibitory effect by Cervitec could not be discerned 12 weeks after varnish treatment.

Adult↗
PubMed1994

Human dental plaque formation on plastic films. A quantitative SEM study.

The initial colonization of bacteria in previously clean teeth or artificial surfaces inserted in mouth has been reported to occur at various periods of time. Rönström et al., using light microscopy, saw that bacteria were present 10 seconds after prophylaxis. Bacterial culture studies have shown that microorganisms associated with the surface coating on tooth surfaces appeared within minutes after prophylaxis. Furthermore, Rönström et al. noted that the number of bacteria increased over a period of four hours. In contrast, ultrastructural investigations of early plaque have demonstrated bacterial colonization only within the first two hours of plaque development in a few samples obtained on a smooth surface and in most samples on a rough surface. However, microorganisms have been found regularly after four hours of plaque accumulation in subjects with healthy gingiva. The aim of the present investigation was to determine the earliest occurrence of bacterial colonization in situ and to observe the pattern of the initial formation of human dental plaque.

Adult↗
PubMed1993

Microbial accumulation and vitality on different restorative materials.

A new technique using standardized test facings was designed to evaluate interdental plaque accumulation on different restoration materials. In 10 volunteers, a total of 40 samples, including enamel, two different ceramics and a bonding composite, were inserted one by one into a precision attachment in an experimental inlay bordering on either the lower second premolar or the lower first molar. Bacterial accumulation on each approximal specimen was allowed to mature for 3 d. Following microbiological processing of the plaque samples, total bacterial counts, colony forming units and the bacterial vitality were determined. The results revealed different accumulation rate patterns. Both ceramics accumulated less plaque with a reduced vitality compared to enamel, while the bonding composite showed no significant differences compared to the natural tooth substance. No significant differences were detected when comparing the two examined ceramics.

Adult↗
PubMed1993

Vital fluorescence: a new measure of periodontal treatment effect.

The purpose of the current study was to determine, by means of a fluorescence test, the ratio between vital and dead bacteria in dental plaque before and two weeks following professional dental prophylaxis. A solution of fluoresceindiacetate (FDA) and ethidium bromide (EB) in normal saline was applied to plaque samples from 82 healthy adults both prior to and 14 days following professional prophylaxis. Living microorganisms were colored green by the FDA while the EB introduced a red color into the nucleic acids of dead cells. The relationships between the vital fluorescence scores and standard clinical measures, plaque index (PlI) and gingival index (GI) were analyzed. Two weeks following professional prophylaxis, a significant decrease was observed in the PlI scores (0.9 +/- 0.4, Day 0; 0.6 +/- 0.3, Day 14, p < 0.001) and the GI scores (1.1 +/- 0.2, Day 0; 0.7 +/- 0.3, Day 14, p < 0.001), while there was a statistically significant increase in the vitality of the dental plaque (74 per cent +/- 9, Day 0; 78 per cent +/- 7, Day 14, p < 0.001). The vital fluorescence (VF) technique may provide an additional explanation of periodontal treatment effect.

Adult↗
PubMed1992

Relationship between bacterial counts, microbial vitality and the accumulation of supragingival dental plaque in humans.

Comparisons between plaque index (PlI) and bacterial counts have been made already; however, these did not take into account the area used for plaque sampling. The objective of the present study was to determine the correlation between the PlI score, the number of bacteria and the bacterial plaque vitality when dental plaque was repeatedly sampled from the same area in each subject during early plaque accumulation. Between intervals of optimal oral hygiene, 10 participants refrained from all oral hygiene measures for periods of 1, 2, 3, 4 and 5 days. The PlI was recorded on the vestibular surface of all first premolars as local PlI:LS. For statistical reasons, the scores of the independent variable LS were added for each subject giving LS* values ranging from 0 to 8. The plaque sampled from this specific surface was circumscribed by the marginal gingiva and an acrylic splint, giving reproducible areas for plaque collection. Total microscopic bacterial counts (BC), colony forming units of anaerobes (CFUan) and aerobes (CFUae), and proportions of vital bacteria (VF) were compared with LS* values. BC and LS* values were strongly correlated. CFUan and CFUae increased significantly with LS*, but this increase was higher for LS* 0 to 4 than for LS* 4 to 8. The ratio between vital and dead microorganisms, assessed by two different methods, was low when an LS* of 0 was recorded, with higher ratios registered for LS* values 4 and 8.

Adolescent↗
PubMed1992

Drinking water fluoridation and caries prophylaxis: with special consideration of the experience in the former East Germany.

Drinking water fluoridation for caries prophylaxis is not a means of primary prevention: i.e., avoidance of sugar and microorganisms in the oral cavity; but rather a means of secondary prevention: e.g., prevention of bacterial production of carboxylic acid from sugar, and therapy: e.g., enhancement of enamel resistance to demineralization by incorporation of fluoride in remineralization of the enamel surface. Currently available epidemiologic studies on the effects of drinking water fluoridation reveal: reduction of the incidence of caries, particularly in children no detrimental health effects; cosmetically undesirable dental fluorosis may occur, however. Nevertheless, introduction of drinking water fluoridation in Germany is not recommendable because of: the greater effectiveness of primary caries prevention, the acceptance of which is reduced, however, by drinking water fluoridation the at least equal prophylactic effect of fluoride via other routes, e.g. via toothpaste the narrow range between beneficial and detrimental dosage the avoidance of fluoride-enriched waste water the prerogative of minimal manipulation of drinking water content.

Dental Caries↗
PubMed1991

[Plaque and chemotherapy concepts of the future].

Various hypotheses have been introduced and discussed in the past decade to explain the aetiology of caries and paradontopathies: Non-specific/group-specific/specific plaque hypothesis, exogenic plaque hypothesis, ecological change theory. Principles and strategies of chemotherapy for dental plaque-related ailments are treated on the basis of these theories.

Amines↗
PubMed1990

Efficacy of Listerine, Meridol and chlorhexidine mouthrinses on plaque, gingivitis and plaque bacteria vitality.

The experimental gingivitis model was used to compare the anti-plaque, anti-gingivitis and anti-microbial efficacies of a phenolic compound (Listerine) and an amine/stannous fluoride mouthwash (Meridol), using a placebo preparation as negative control and a chlorhexidine solution as positive control in a double-blind study. After professional toothcleaning, 36 volunteers performed optimal oral hygiene for a period of 2 weeks. They then ceased all oral hygiene procedures for 21 days during which they rinsed twice daily with 1 of the 4 mouthrinses. After 3 weeks of rinsing, plaque indices remained the lowest in the chlorhexidine group, while subjects using Listerine or Meridol harbored similar indices significantly lower than that of individuals rinsing with the placebo solution. Up to that time, the gingival index scores were equal in all groups except for the chlorhexidine group in which the values only amounted to half of these encountered in the other groups. The plaque vitality scores showed a bactericidal effect in vivo of chlorhexidine during the entire time of experimental gingivitis. In contrast, the data gave no evidence of an antibacterial effect in vivo of Listerine. The efficacy of Meridol to kill micro-organisms was similar to chlorhexidine during the early stages of plaque accumulation and, with time, became insignificant. This study has demonstrated that chlorhexidine was superior to Listerine and Meridol in its ability to maintain low plaque scores and gingival health during this 3-week period of no mechanical oral hygiene. Moreover, it was also shown that Meridol was as effective as Listerine in reducing plaque accumulation and, in contrast to Listerine, possessed a remarkable but transient antibacterial effect in vivo.

Adult↗
PubMed1990

[Plaque accumulation on various veneering resins--a clinical study].

Initial plaque accumulation on five veneering resins was investigated to determine differences in vitality and adhesion of microorganisms. After 24 hours of exposure of the specimens in the mouth, the vitality of the bacteria was reduced. The vitality and the adhesion increased only a little until the fourth day. The high plaque accumulation observed in vivo on resin veneers seems to depend primarily on the degeneration and mechanical lesions of the surface after a certain time in mouth.

Bacterial Adhesion↗
PubMed1990

[In-vivo corrosion tests of dental alloys in relationship to saliva pH].

The corrosion of four dental alloys and titanium was studied in relationship to saliva pH and plaque accumulation in vivo. Test specimens were scanned for porosities with an image analysis system before and after exposure to the oral milieu. The saliva pH was monitored during the study period. After four days of exposure in the mouth the plaque accumulation and the vitality of the plaque on the alloy surfaces was evaluated. Plaque accumulation and mean saliva-pH were not correlated with the observed surface corrosion. The least surface effects were observed on titanium, which showed the highest plaque accumulation. Different alloys showed different bacteriostatic effects. The least amount of living bacteria was found on titanium. Plaque accumulation and bacteria vitality depended on material and test person.

Corrosion↗
PubMed1989

Direct measurement of the bactericidal effect of chlorhexidine on human dental plaque.

The purpose of the present study was to determine by means of a fluorescence test the ratio between vital and dead bacteria in dental plaque before and after 0.1% chlorhexidine rinses. Plaque was stained by fluoresceindiacetate (FDA), which gave a green color to the living micro-organisms, and by ethidiumbromide (EB), which introduced a red color into the nucleic acids of the dead bacteria. 1-, 2- and 3-day-old undisturbed plaque harbored 80 to 85% living micro-organisms. 1 h after chlorhexidine use, this % was reduced to a plateau of 19 to 34% of vital bacteria present in the sampled plaque. Between 6 and 8 h later, this % rose towards its original value. This study has shown that FDA/EB staining provides a method for direct measurement of bacteria vitality in dental plaque and, as such, can be of great value for testing the efficacy of various antiplaque agents.

Adult↗