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The purpose of this 4-day plaque regrowth study was to assess the effect of N-chlorotaurine (NCT) mouth rinses on plaque inhibition and plaque vitality. Eighty volunteers participated in this investigator-blind, randomized, clinical controlled study in parallel groups. No oral hygiene was permitted except rinsing with a 2% or 3% NCT mouth rinse, a positive or a negative control. Primary parameters were the plaque index (Silness and Löe, Acta Odontol Scand, 22:121-135, 1964) and plaque vitality (Netuschil et al., J Clin Periodontol, 16:484-488, 1989) after the final rinse. In addition, another plaque index (Turesky et al., J Periodontol, 41:41-43, 1970), plaque area, and bleeding on probing were recorded. All parameters were taken at baseline and day 5. U test was applied on a 5% error level. No differences in plaque inhibition were found between the two NCT formulations and the negative control. However, a statistically significant reduction of plaque vitality compared to the negative and positive control was observed. Discoloration of the tongue and unpleasant taste were recorded in participants in the NCT groups. NCT mouth rinses did not inhibit plaque regrowth, but they did reduce the vitality of plaque bacteria. Methods of prolonging the substantivity of the NCT mouth rinses should be investigated to enhance the antibacterial properties of these formulations.

Objective: The aim of this experimental gingivitis study was to assess the efficacy and safety of two new chlorhexidine (CHX) mouthrinses., Material and Methods: Ninety volunteers participated in this investigator-blind, randomized, clinical-controlled trial in parallel groups. During the treatment period, no oral hygiene measures except rinsing with non-alcoholic 0.2% CHX or 0.2% CHX/0.055% sodium fluoride mouthrinses, a positive control, or a negative control were permitted. The primary parameter was the gingival index; the secondary parameters were plaque index, discolouration index, and bleeding on probing. Clinical examinations were conducted 14 days before the start of the study, at baseline, and after 7, 14, and 21 days. The two sample t-test, anova, and ancova were used for the statistical analysis., Results: No difference in efficacy was found between the two new CHX formulations and the positive control. On day 21, statistically significantly less gingival inflammation and plaque accumulation compared with placebo were observed. Besides discolouration and taste irritations, no adverse events were recorded., Conclusion: The two new CHX mouthrinses were able to inhibit plaque re-growth and gingivitis. Neither the omission of alcohol nor the supplementation with sodium fluoride had weakened the clinical efficacy of CHX with respect to the analysed clinical parameters.

Background: The minor efficacy of chlorhexidine (CHX) on other cariogenic bacteria than mutans streptococci such as Streptococcus sanguinis may contribute to uneffective antiplaque strategies., Methods and Results: In addition to CHX (0.1%) as positive control and saline as negative control, two chitosan derivatives (0.2%) and their CHX combinations were applied to planktonic and attached sanguinis streptococci for 2 min. In a preclinical biofilm model, the bacteria suspended in human sterile saliva were allowed to attach to human enamel slides for 60 min under flow conditions mimicking human salivation. The efficacy of the test agents on streptococci was screened by the following parameters: vitality status, colony-forming units (CFU)/ml and cell density on enamel. The first combination reduced the bacterial vitality to approximately 0% and yielded a strong CFU reduction of 2-3 log(10) units, much stronger than CHX alone. Furthermore, the first chitosan derivative showed a significant decrease of the surface coverage with these treated streptococci after attachment to enamel., Conclusions: Based on these results, a new CHX formulation would be beneficial unifying the bioadhesive properties of chitosan with the antibacterial activity of CHX synergistically resulting in a superior antiplaque effect than CHX alone.

The aim of this double-blind, 28-week study was to evaluate the plaque-inhibitory and antigingivitis efficacy of a fluoride toothpaste containing 0.3% triclosan and essential oil (Dental Kosmetik, Dresden, Germany) in comparison with a control toothpaste. One hundred twenty subjects previously treated for chronic periodontitis were included in the study. At baseline, 8, 18, and 28 weeks, plaque accumulation (PlI) and gingival status (GI) were assessed. Probing pocket depth (PD) and bleeding on probing (BOP) were measured at baseline and week 28 using a Florida probe. No professional hygiene was delivered during the study period. Mean plaque scores decreased between baseline and week 8 in both groups. At the end of the study, a significant increase of mean PlI compared to baseline could be observed in the test and in the control groups. Comparing the two groups, the PlI in the triclosan group was significantly lower than in the control group. Mean gingival scores decreased significantly during the first 8-week period in both groups. This reduction was followed by an increase of GI in the control, while the GI in the test group reached a significantly lower value than in controls after 28 weeks. Furthermore, at week 28, in both groups the PD were decreased as compared to the pre-study data. It is concluded that the triclosan/essential oil additive in a fluoride-containing dentifrice exhibited distinctive antigingivitis as well as plaque-inhibitory effects during a 28-week maintenance period in periodontitis patients.

To investigate the arrangement of biofilms formed in vivo, volunteers wore splints with slabs of six different dental materials inserted to collect smooth surface plaque. After 5 d of undisturbed plaque accumulation, the specimens were vital stained and analyzed by the confocal laser scanning microscopy (CLSM) to evaluate the percentage of vital biofilm microflora (VF percentage). Further parameters were the area of the specimens covered by plaque (surface coating; SC, %) and the height of the biofilms (BH, pm). The metals amalgam and gold, the compomer, as well as the glass-ionomer cement harboured an almost entirely dead biofilm (VF <8%). Resin composite led to vitality values between 4 and 21%, while a very thin biofilm on ceramic revealed the highest vitality values (34-86%). SC varied from 6% on glass-ionomer cement to 100% on amalgam. BH reached its highest value on amalgam and gold of 17 and 11 microm, respectively, while heights of between 1 and 6 microm were found on the ceramic, resin composite, compomer and the glass-ionomer cement. Within their limits, the present findings indicate that amalgam, gold, compomer and glass-ionomer cement exert an influence against the adhering biofilm. No general relationship could be established between the different parameters VF percentage, SC percentage and BH (microm).

Background: A common clinical observation following surgical periodontal therapy with an enamel matrix derivative (Emdogain) is the improved healing of the soft tissues and the limited inflammation of the operated areas. These clinical observations are empirical and difficult to explain. One of the factors influencing the early wound healing might be a potential antimicrobial effect of Emdogain., Aim: To investigate the effect of Emdogain on the vitality of ex vivo supragingival dental plaque and to compare this effect to that of a standard 0.2% chlorhexidine solution., Materials and Methods: 24 patients suffering from adult periodontitis were included in the study. At the beginning of the experiment, all participants were given a professional tooth cleaning. For the following 4 days, they had to refrain from any kind of oral hygiene measures. At day 5, from each of the volunteers, a voluminous plaque biofilm sample was taken with a sterile curette from the vestibular surfaces of the 1st lower molars and divided into 5 equal parts. Each part was mounted with 5 microl of the following solutions: (1) NaCl, (2) enamel matrix derivative dissolved in water (EMD), (3) enamel matrix derivative dissolved in the vehicle (Emdogain), (4) vehicle (propylene glycol alginate, PGA), (5) 0.2% chlorhexidine digluconate (CHX). After a reaction time of 2 min the test solutions were sucked off, and subsequently the biofilm was stained with a fluorescence dye. The vitality of the plaque flora after the treatments was evaluated under the fluorescence microscope (VF%)., Results: Plaque samples treated with NaCl showed a mean vitality of 76.8+/-8%. The EMD, Emdogain, PGA and CHX showed VF values of 54.4+/-9.2, 21.4+/-10.6%, 19.6+/-11.6% and 32.3+/-11.8%, respectively. Emdogain, PGA and CHX showed statistically highly significant reductions (p<0.0001) in terms of bacteria vitality when compared to water (negative control) and EMD. Both Emdogain and PGA were found to be statistically significantly different compared to CHX (p<0.001) (positive control)., Conclusion: The results of this study indicate that Emdogain might have an antibacterial effect on the vitality of the ex vivo supragingival dental plaque flora.

The aim of this randomized, parallel-group, placebo-controlled, blind clinical study was to examine the dental plaque and the gingivitis inhibitory effects of two low-dose 0.06% chlorhexidine (CHX) preparations in comparison to a commercially available 0.1% CHX solution, an amine fluoride/stannous fluoride (ASF) solution and a water control as an adjunct to the daily mechanical oral-hygiene measures. After prophylaxis, 81 medical students performed their tooth cleaning and were asked to rinse for 30 s, according to the instructions given by the manufacturers with the assigned amount of the following solutions: once daily 10 ml ASF 250 ppm or twice daily each 10 ml CHX 0.06% with fluoride, 10 ml CHX 0.06% without fluoride, 15 ml CHX 0.1% or 100 ml tap water. The plaque index (PlI), the gingival index (GI) and the discoloration index (DI) were taken at day -14 and months (M) 0, 1, 2, 3 and 6. In this study group with good oral hygiene, all test products led to a reduction of the PlI scores when used as supplements to the usual mechanical hygiene measures. At M3 subjects using both the 0.1% as well as the 0.06% CHX showed significantly less plaque accumulation than those using ASF. In the GI a significant difference between the control and 0.1 % CHX was found at M3 and at M6. If a further decrease in the GI is wanted, a minimum concentration of 0.1% CHX for long-term use in association with habitual cleaning is needed, which, however, should be limited to special patients. If maintaining clinical health is the goal, the other solutions are a good alternative to 0.1% CHX because they exhibit less staining.

To examine the spatial structure of dental biofilms a vital fluorescence technique was combined with optical analysis of sections in a confocal laser scanning microscope (CLSM). Enamel slaps were worn in intraoral splints by three volunteers for five days to accumulate smooth-surface plaque. After vital staining with fluorescein diacetate and ethidium bromide the specimens were processed for CLSM examination. Optical sections 1 microm apart were analysed in the z-axis of these dental biofilms. One of the films was 15 microm high, sparse and showed low vitality, i.e. <16%, while the others were taller (25 and 31 microm) and more vital, i.e. up to 30 and 69%, respectively. In all instances the bacterial vitality increased from the enamel surface to the central part of the plaque and decreased again in the outer parts of the biofilm. The spatial arrangement of the microorganisms in the biofilm showed voids outlined by layers of vital bacteria, which themselves were packed in layers of dead material.

Confocal microscopy and vital fluorescence techniques were combined for the first time to investigate ex vivo human dental plaque. The vital fluorescence technique used discriminates vital from dead cells, while confocal laser scanning microscopy allows the optical sectioning of undisturbed biofilms leaving the samples intact during analysis. The concomitant use of both methods made an examination of the three-dimensional architecture of dental plaque possible. The topography of plaque biofilms that were allowed to accumulate in situ on glass and enamel was recorded. The distribution of plaque microflora vitality as well as its accumulation varied according to plaque age. A plaque thickness of up to 8, 35 and 45 microm was estimated ex vivo on enamel after 1, 2 and 3 days, respectively. Young and sparse plaque biofilms consisted mainly of dead material. Vital bacteria were observed on top of this dead layers.

The aim of this double-blind study was to enumerate the total number of living and dead bacteria on defined tooth areas during the application of antibacterial mouthrinses. After prophylaxis, 40 students refrained from all oral hygiene measures for 3 d, during which they rinsed with a phenolic compound (Listerine), an amine fluoride/stannous fluoride solution (Meridol), 0.2% chlorhexidine (CHX) or a control solution (0.02% quinine-hydrochloride). The plaque index (P1I) was recorded at the start and the end of the investigation. Total bacterial counts (BC) and colony-forming units (CFU) of 1d-, 2d- and 3d-old dentogingival plaque were determined. The plating efficiency (PE) was calculated as a percentage of CFU/BC and the portion of vital microflora estimated by a vital fluorescence technique (VF). All groups started with a P1I approximating 0.1. On day 3, the P1I values were 1.21 in the control group and 0.51, 0.37 and 0.14 after Listerine, Meridol and CHX use, respectively. A tremendous variation existed between the numbers of viable bacteria found per mm2 on the enamel surface and day 3 (CHX: 0.2; Meridol: 300; Listerine; 6x10(4); control: 2x10(6)), while higher total numbers of bacteria were concomitantly present (CHX and Meridol: 1-2x10(4); Listerine: 2x10(5); control: 2x10(6)). Both vitality parameters PE and VF reached 92% in the control group at day 3, but only 7% after CHX use. With Meridol and Listerine, the corresponding PE values were 3% and 43%, respectively, while the VF values reached 48% and 54%. The PII, BC, CFU and PE values of the CHX and the Meridol groups differed significantly from those of the control group. In contrast, Listerine showed no difference as compared to the control rinse. Due to the strong antibacterial action of CHX and Meridol during their use, almost only dead or non-proliferating bacteria were found on the tooth surfaces. Thus, only a thin plaque could develop. As a clinical consequence, both substances showed retardation of plaque development as reflected by significantly reduced plaque indices.

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.

The objective of this investigation was to determine the microbial generation time during early human supragingival plaque formation. On 2 occasions, 13 participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was sampled from defined areas of the teeth 13, 14, 15, 23, 24 and 25. Two independent methods were used to estimate the total number of viable cells: colony-forming units BCVF, total bacterial counts (BC) as enumerated by microscopic examination, and the percentage of vital bacteria using a vital fluorescence technique (VF) were recorded. The total number of vital microorganisms was calculated by BCVF (= BC x VF). The generation time based on either colony-forming units or BCVF increased significantly with plaque age. During the first interval (1-4 h), the microbial multiplication took slightly less than 1 h. After the establishment of a more mature plaque (24-72 h), the replicating time was between 12.5 h (BCVF) and 14.8 h (colony-forming units). It was concluded that the microbial generation time recorded at the initial stages of plaque formation is considerably lower than that found in older plaque.

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.

The aim of the present study was to compare the effect on plaque growth and gingival response of Meridol, an amine/stannous fluoride solution, during a three-month investigation, with those of a placebo preparation as a negative control and a chlorhexidine solution as a positive control, in a double-blind study. After having their teeth professionally cleaned, 36 volunteers continued their usual oral hygiene for a period of two weeks. Their teeth were then polished again (month 0) after which they rinsed twice daily (morning and evening) with one of the three mouthrinses in addition to their habitual toothcleaning. After three months of rinsing, plaque indices remained lowest in the chlorhexidine group, although the subjects using Meridol had indices significantly lower than those of individuals rinsing with the placebo solution. The gingival index scores in the Meridol group were higher than in the chlorhexidine group and lower than in the placebo group. The plaque vitality scores showed a bactericidal effect in vivo with chlorhexidine and Meridol during the entire experiment. The use of Meridol resulted in more toothstaining than with the placebo, but significantly less than with chlorhexidine. This study demonstrated that Meridol reduced plaque accumulation, retarded gingivitis development, possessed a definite bactericidal action, and produced only slight toothstaining.

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.

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.

PMN elastase concentration of gingival crevicular fluid (GCF) was investigated in 11 healthy volunteers before professional tooth cleaning and after a 5-week period of intensive oral hygiene. GCF was collected using filter paper strips and the enzyme concentration was evaluated by the ELISA-technique. Intensive daily oral hygiene led to a considerable improvement in the clinical indices and to a reduction in the concentration of elastase in GCF. Despite the changes in the oral hygiene status, functional elastase was still present in the samples at the end of the experiment. This could mean that even at clinically healthy sites there is a lack of alpha-1-proteinase inhibitor, the major serum protein inactivating PMN elastase.

The anti-plaque, anti-gingivitis and anti-microbial efficacies of a phenolic compound (Listerine) and 2 different amine/stannous fluoride mouthwashes (Meridol I, II) were compared when these solutions were used in addition to usual tooth cleaning. A placebo preparation was utilized as a negative control and a chlorhexidine solution as a positive control in this double-blind study. After professional tooth cleaning, 49 volunteers continued their habitual, self-performed and non-supervised oral hygiene for a period of 2 weeks, in order to have a more standard baseline. At day 0, they began to rinse twice daily with 1 of the 5 mouthwashes. After 3 weeks of rinsing, plaque indices remained the lowest in the chlorhexidine and the Meridol I groups, while subjects using Listerine or Meridol II demonstrated similar indices significantly lower than that of individuals rinsing with the placebo solution. Through this period, the gingival index scores were similar in the Meridol, Listerine and chlorhexidine groups. At day 21, the mean GI scores in the chlorhexidine group were significantly lower than the scores in the placebo group. The plaque vitality scores showed a bacterial effect in vivo of chlorhexidine and, to a lesser extent, of the Meridol solutions. No substantial evidence of an antibacterial effect in vivo was found for Listerine. This study has demonstrated that when mouthrinses are used to supplement habitual mechanical oral hygiene, chlorhexidine remains the most powerful solution. Furthermore, it was also shown that a combination of habitual self-performed and non-supervised oral hygiene with Meridol or Listerine is more beneficial for plaque control than the use of mechanical oral hygiene alone.

Different studies have shown that various substances may have an influence on early human dental plaque formation. The purpose of the present study was to compare on tooth substances and supporting prosthetic materials the amount of plaque deposition by SEM and the quantity of selected bacteria using anaerobic culturing techniques. 5 bridges, replacing a missing molar or premolar, were incorporated in 3 patients. In the midbuccal area of each pontic, a semi-precision attachment was placed allowing the insertion of the following test facings: enamel, dentine, non gamma 2-amalgam, alloys of 85% and 55% gold, silver-palladium, chrome-cobalt, chrome-cobalt-titanium, and ceramic. For each material, 2 facings were fabricated. After 4 and 24 hours in situ, bacteriological samples were taken and processed for further identification. After a 2nd period of 4 and 24 hours in situ, the same facings were carefully removed and prepared for SEM-examination. All 4-hour specimens exhibited various areas covered by plaque, the amount of which varied with the different supporting substances. The very smooth surfaces (e.g., gold) harbored sparse deposits, while the rougher (e.g., amalgam) were covered by more plaque. After 24 hours of plaque development, an increase in the number of micro-organisms was noted for all the specimens. After 4 and 24 hours of plaque accumulation, no specific trends suggesting a preferential colonization on the different substances were observed. This study has shown that the amount of early deposits on different substances seems to be related to the degree of their surface roughness, while plaque formation was qualitatively similar.

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.

The effect of chlorhexidine on early plaque formation was studied in vivo in order to assess potential structural and quantitative changes. 3 subjects with healthy gingiva were used. Plastic films were applied to the buccal surfaces of the maxillary right first premolars and plaque was allowed to form for either 4 or 24 h. A single 1-min rinse with 0.2% chlorhexidine digluconate was used for the 4-h experiments, 1 min after film placement, whereas, for the 24-h experiments, an additional 1 min rinse was used at 12 h. In total, 62 films were obtained, half treated and half controls. These were processed for light and transmission electron microscopy, using standardized techniques for area sampling and cell counting. All plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. In the controls, an important increase in bacterial count was seen between 4 and 24 h, whereas the increase with chlorhexidine was slight. There were fewer bacteria in the chlorhexidine as compared to the water specimens, for both time periods. Many microorganisms in the chlorhexidine samples appeared to be undergoing degeneration with coagulated cytoplasm and disrupted cell walls.

During six month of abolished oral hygiene and concomitant development of gingivitis, the buccal subgingival microbiota was studied by darkfield microscopy as well as by cultural methods. Five dental students gave written informed consent and participated in this trial. In darkfield microscopy there was a slow reduction in the proportion of coccoid forms concomitant with an increase in the proportion of rods, while spirochetes were rarely detected during the entire experimental period. However, the cultural data revealed a decrease of the Gram-positive facultative and an increase of the Gram-negative anaerobic microorganisms after 6 months of abolished oral hygiene. The bacteriological data show, that in buccal sites--even after 6 months of abolished oral hygiene--the subgingival microflora reflects a population typical only for an initial lesion.

The influence of oral hygiene on early plaque formation has been studied. The amount and structure of dental deposits formed on plastic films were determined at two occasions with or without a preceding period of effective oral hygiene. Six human subjects developed plaque during 4 hours on plastic films applied to the buccal surfaces of premolars and cuspids. The plastic films with adhering deposits were processed for electron microscopy. In presence of healthy gingiva, the plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. The microorganisms were almost exclusively Gram-positive cocci. When plaque formation was preceded by a week of excluded oral hygiene, the deposits collected on the same teeth exhibited a threefold increase in the number of bacteria. The relative composition of the flora was altered, as evidenced by a higher number of Gram-negative cells as well as the occurrence of rods and filamentous organisms. The results indicate that neglect of oral hygiene favors an earlier establishment of a complex bacterial flora at the dento-gingival region of the buccal surfaces of premolars and cuspids.

During 21 days of abolished oral hygiene and developing gingivitis the microbial changes were studied in buccal and interdental sites. The subgingival plaque of 6 dental students was analyzed by darkfield microscopy. The microbiota found in interdental sulci showed a higher complexity than that of buccal sites. Buccally and interdentally there was a significant increase in the total number of microorganisms between days 0 and 21. Yet, the development of gingivitis was slower in the buccal than in the interproximal sites. For all bacteria, but specially for more disease-associated morphotypes the accumulation rate was higher interdentally than buccally.

The influence of water, glucose and sucrose rises on early plaque formation has been studied. The amount and structure of dental deposits formed on plastic films were determined on four occasions: no rinsing, water, glucose or sucrose rinses. Five subjects with healthy gingiva developed plaque in 4 h on plastic films applied to the buccal surfaces of premolars and canines, after which period the plastic films with adhering deposits were processed for electron microscopy. Sections were prepared for examination in the light and electron microscope. Some were stained for the demonstration of carbohydrates according to the periodic acid thiocarbohydrazide osmium tetroxide technique. Furthermore, the number of cellular elements collected on the films during the four experiments was calculated and statistically compared. The results in the four groups were identical. The plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. The microorganisms were almost exclusively Gram-positive cocci. Many bacteria exhibited intracellular polysaccharides. The results indicate that the rinsing procedure does not influence early plaque formation, and that frequent mouthrinses with glucose or sucrose have no detectable effect on plaque growth at this initial stage of bacterial adherence.

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.

The aim of the present study was to compare stereologically the histopathologic variations following 3 weeks of chemical (chlorhexidine) or mechanical plaque control. 18 students and dental hygienists volunteered for this investigation. After prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching 0. Six of them then performed mechanical plaque control of 3 weeks (control), while the other 12 rinsed 3 times daily with a 0.12% chlorhexidine solution (test). At days 0 and 21, the plaque index (PlI), the gingival index (Gl) and the gingival exudate flow rate (GEFR) were assessed and biopsies were obtained from buccal sites. Point-counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells, macrophages and mast cells were estimated by counting the number of nuclear profiles of these cells in a specific connective tissue area adjacent to the apical termination of the junctional epithelium. After 21 days, the PlIs of the test subjects were significantly higher than the PlIs of the controls, but their Gl were similar. At the end of the experimental period, the various volume fractions and %s of cell profiles remained stable with the exception of an increase in the %s of lymphocytes in the test group. This study has shown that, clinically as well as histologically, the daily use of chlorhexidine for a 3-week period is equally efficient as optimal mechanical tooth cleaning in maintaining a healthy gingiva in the buccal sites investigated.

The aim of the present study was to investigate stereologically the histologic alterations occurring during gingival healing after experimental gingivitis and to compare clinical parameters with histological findings. 8 dental students volunteered for the investigation. After a prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching zero. They then abolished all oral hygiene procedures for a period of 21 days. After this experimental gingivitis phase, they again performed optimal oral hygiene for 8 days to restore gingival health. At days 0, 1, 2, 4 and 8 after experimental gingivitis, the plaque index (PlI), the gingival index (GI) and the gingival exudate flow rate (GEFR) were assessed and their buccal gingiva was biopsied. Point counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells and macrophages were estimated by counting the number of profiles of these cells in a specific connective tissue area adjacent to the apical end of the junctional epithelium. A rapid drop in the PlI was noted with increasing time after oral hygiene, followed by a slower decrease in the GI and GEFR scores. The histological picture during the entire experiment was that of an initial gingival lesion. At day 0, no chronic inflammation of the gingiva characterized by a predominance of plasma cells was observed. After resumption of oral hygiene when the relative cell numbers at day 0 and day 8 were compared, only an increase in the PMN population was observed. As GI and GEFR scores decreased no significant changes were noted in the relative numbers of the various cell types. These observations suggest that the "physiogenesis during experimental health" appears first clinically and then histologically, and hence, it may take more than 8 days to observe significant variations in cell populations. [ABSTRACT FROM AUTHOR]

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The article presents a comparison between histological and clinical parameters during human experimental gingivitis. The purpose of this investigation was to study stereologically the histopathologic alterations occurring during a human experimental gingivitis, and to establish a relationship between clinical parameters and histologic findings. Eight dental students volunteered for the study. After a prophylaxis they performed optimaI oral hygiene For 3-4 weeks to reach mean plaque and gingival indices approaching zero.

The experimental gingivitis model was used to compare the antigingivitis, antiplaque, and antimicrobial efficacies of two commercially available (a phenolic and a plant alkaloid) compounds used as mouthrinses with those of a mouthrinse containing chlorhexidine digluconate. Thirty-one male and female volunteers with healthy gingivae and clean teeth ceased all oral hygiene procedures for 21 days during which they rinsed twice daily with: a) a phenolic compound (Listerine®), b) sanguinarine (Viadent®), c) 0.12% chlorhexidine digluconate, or d) a placebo mouthrinse. After 21 days of rinsing, virtually no signs of clinical gingivitis were observed in the chlorhexidine group. Subjects rinsing with Listerine, Viadent, or placebo developed clinical signs of gingivitis as measured by gingivitis occurrence, severity, and the proportion of gingival bleeding sites. At the same time, plaque accumulation was only slightly higher than at baseline in the chlorhexidine group, while the Listerine, Viadent, and placebo groups had significantly greater plaque accumulations, particularly during the initial period of treatment between day 0 and day 7. Microbiological enumeration of supragingival plaque collected at the end of the treatment period showed that chlorhexidine digluconate reduced plaque bacteria by 62-99% compared to the placebo group. No significant reductions in plaque bacteria were found among subjects using Listerine or Viadent. This study demonstrated that 0.12% chlorhexidine digluconate was superior to Listerine and Viadent in its ability to maintain optimal gingival health during the entire three weeks of mouthrinse use. It was of particular interest to note these effects during the final 14 to 21-day period of extreme challenge in this experimental model when gingivitis severity and bleeding site occurrence are most pronounced in the placebo group. [ABSTRACT FROM AUTHOR]