The effect of mouthrinses containing zinc and triclosan on plaque accumulation, development of gingivitis and formation of calculus in a 28-week clinical test

Abstract Experimental mouthrinses containing 0.4% zinc sulphate and 0.15% triclosan, which differed in base formulations were compared to a commercially available non-active control mouthrinse. Following baseline clinical examinations for plaque, gingival bleeding and calculus, the volunteers were provided with a dental prophylaxis and given oral hygiene instruction, stratified into 3 groups and given 1 of 3 mouthrinses. Further clinical assessments were performed after 4. 16 and 28 weeks. Salivary mutans streptococci were also monitored during the study. At 4 weeks, plaque and calculus scores in all groups were low compared to baseline. During the remainder of the study, these improvements were not maintained and both plaque and calculus levels increased in all groups. Plaque was significantly lower (p<0.05) than in the control at all time points. Calculus was significantly lower at week 28 for experimental mouthrinse group 2. Gingival bleeding also decreased in the initial 4 weeks but increased thereafter in the control group. In contrast, gingival bleeding was significantly (p<0.05) lower in the two experimental groups than in the control group. No significant changes in mutans streptococci were observed.     

The effect of 3 mouthrinses on plaque and gingivitis development.

The aim of this study was to evaluate the effect of 3 mouthrinses, Listerine Antiseptic (thymol), Peridex (chlorhexidine), Perimed (povidone iodine and hydrogen peroxide), and a placebo (water) on the development of dental plaque and gingivitis, when used as the only oral hygiene procedure for 14 days. 71 subjects were entered into a randomized, double-blind study. At the baseline examination, papillary bleeding score (PBS), and plaque index (PI) were registered, after which subjects received supragingival prophylaxis and were assigned to 1 of 4 study cells. Subjects were asked to refrain from all oral hygiene procedures except for the supervised 14-day 2 x daily rinsing with the assigned preparation. At day 14, the same clinical parameters were again registered. Statistical analysis was performed by a one-way analysis of variance (ANOVA) to compare the 4 groups, followed by Duncan's multiple range test to determine specific group differences. At baseline, average PBS and PI scores were similar for all 4 groups. After 14 days, the average PBS for Peridex and Perimed was significantly lower than for Listerine Antiseptic and water. The frequency of interdental units with a PBS greater than 2 was significantly lower for Peridex and Perimed than for Listerine Antiseptic and water. We concluded that both Peridex and Perimed were effective in reducing plaque and gingivitis when used as a 2 x daily mouthrinse by subjects refraining from other oral hygiene procedures. In vitro, a synergistic effect was assumed when inhibition was achieved with Perimed at the same or greater dilution than was achieved with povidone-iodine alone.     

Influence of alcohol in mouthwashes containing triclosan and zinc: an experimental gingivitis study

OBJECTIVES: An experimental gingivitis model was used to analyse the influence of alcohol in mouthwashes containing 0.15% triclosan and zinc chloride on the formation of supragingival plaque, the development of gingivitis and the appearance of adverse events. MATERIAL AND METHODS: Using a double-blind crossover design, 30 subjects underwent two consecutive experimental phases with two 0.15% triclosan and zinc chloride mouthwashes, differentiated mainly by their excipient (hydroalcoholic or aqueous). In each phase, the subjects discontinued all oral hygiene measures and were treated solely with the randomly assigned experimental mouthwash for 21 days. Each experimental phase was preceded by a 14-day washout period in which, after receiving a complete oral prophylaxis, the subjects were instructed to perform thorough oral hygiene procedures. Gingivitis and plaque levels were assessed at the start and end of both the experimental phases. RESULTS: The evolution of the gingivitis and plaque indices showed no statistically significant differences between both treatments. The mean gingival index increased from 0.30 to 0.38 with the non-alcoholic mouthwash and from 0.32 to 0.42 with the hydroalcoholic mouthwash. The respective changes in plaque index were from 0.88 to 1.93 and from 0.94 to 1.92. The hydroalcoholic mouthwash produced a larger number of fresh symptoms (p=0.033), oral itching being the most reported. CONCLUSIONS: Alcohol does not influence the effectiveness of a 0.15% triclosan and zinc chloride mouthwash against gingivitis development and supragingival plaque formation. The absence of alcohol significantly decreases the incidence of adverse events produced by the mouthwash.     

Effect of two new chlorhexidine mouthrinses on the development of dental plaque, gingivitis, and discolouration. A randomized, investigator-blind, placebo-controlled, 3-week experimental gingivitis study

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.     

The effect of a triclosan-containing dentifrice on established plaque and gingivitis

Abstract The aim of the present clinical trial was to study the effect on existing plaque and gingivitis of an oral hygiene regimen which utilized a dentifrice which contained triclosan. 120 subjects were recruited for the trial. They were examined for plaque and gingivitis using the criteria of (i) the Turesky modification of the Quigley & Hein plaque index and (ii) the Löe & Silness gingival index. Plaque and gingivitis were assessed in all parts of the dentition and at 6 location points around each tooth. Following a baseline examination, the subjects were stratified in 2 balanced groups based on age, plaque and gingivitis scores. The subjects were randomly assigned to the following treatment: 1 test group used a dentifrice containing triclosan/copolymer/fluoride and 1 control group used a traditional fluoride containing dentifrice. The participants were given the assigned dentifrice and a soft-bristled toothbrush for home use. They were instructed to brush their teeth in the morning and in the evening for one minute each time. They were re-examined 6 weeks, 3 and 6 months after the baseline examination. The findings from the re-examinations revealed that an oral hygiene regimen which utilized a dentifrice which contained triclosan/copolymer significantly reduced pre-existing plaque and gingivitis above what was accomplished by a traditional fluoride containing dentifrice. The improvement of the gingival conditions occurred in all parts of the dentition and at all tooth surfaces and units. In addition, the present data support the hypothesis that triclosan may induce alterations in the quality of existing plaque.     

Inhibitory effect of benzethonium and zinc chloride mouthrinses on human dental plaque and gingivitis

Abstract In a double-blind study the plaque- and gingivitis-inhibiting capacities of three aqueous mouthrinse solutions of benzethonium chloride, zinc chloride, and benzethonium chloride combined with zinc chloride were compared to those of a placebo mouthrinse. Forty-three adults with clean teeth and healthy gingiva were randomly assigned to the treatment and control groups. All participants received an initial prophylaxis. Assessments of plaque and gingivitis were made before and after a 10-day test period. During this time the subjects suspended oral hygiene procedures and rinsed daily with 20 ml of their respective rinse solutions. According to the measurements made before and after the test period, the mouthrinse containing benzethonium chloride produced 42 to 42.9 % less plaque than any of the other three formulations. The differences were statistically significant (P < 0.05). Gingivitis scores of the four groups did not differ significantly. These findings indicate that benzethonium chloride is a moderately effective antiplaque agent.     

Six-month study of the effect of a dentifrice containing zinc citrate and triclosan on plaque, gingival health, and calculus

Abstract – In two previous studies gingival health was maintained for at least 12 months by a dentifrice containing zinc citrate and triclosan. The aims of the present study were to determine if a zinc/triclosan dentifrice would stabilize gingival health if a lower concentration of zinc was used and to investigate its effect on the formation of calculus. 101 men and women were given oral hygiene instruction and their teeth were professionally cleaned. Two balanced groups were then formed, based on the prestudy levels of gingival bleeding and calculus. One group used the zinc/triclosan dentifrice for 6 months, while the other used a control. Results were assessed after 3 months and 6 months. Following the oral hygiene instruction, plaque and gingival bleeding were assessed at the end of the 4-wk period preceding the experimental phase, and both had been reduced. This improvement was not maintained by the control group, whereas the test group exhibited significantly lower plaque levels and a higher standard of gingival health throughout the 6 months. After 3 months, levels of calculus in the control group had returned to prestudy levels. At both the 3- and 6-month assessments, significantly less calculus was observed in the test group. The improved plaque control, stabilized gingival health, and reduced calculus formation support the conclusion that a dentifrice containing 0.5% zinc citrate and 0.2% triclosan can contribute to oral care.     

Comparison between 3 triclosan dentifrices on plaque, gingivitis and salivary microflora

Abstract 3 triclosan-containing dentifrices were compared in a 6-month, un-supervised tooth brushing study. The effects on plaque, gingival bleeding and certain salivary micro-organisms (mutans streptococci, lactobacilli, total counts of streptococci and total counts of micro-organisms) were evaluated. 123 subjects were divided into 4 groups according to severity of gingival bleeding index. 112 subjects completed the study. Following a 4-week pre-experimental period, using a sodium monofluorophosphate dentifrice (placebo), the subjects were assigned to use one of 3 triclosan-containing dentifrices, available on the Swedish market: Colgate Paradent (a triclosan/copolymer dentifrice) (n=26); Pepsodent Gum Health (a triclosan/zinc citrate dentifrice) (n=31); Dentosal Friskt Tandkött (a triclosan/pyrophosphate dentifrice) (n=28); or to continue with the placebo (n=21). The results revealed that Colgate Paradent reduced baseline plaque values by 39% (Quigley and Hein) over the 6-month experimental period. The corresponding values for the other modalities were: a reduction of 6% for Pepsodent Gum Health, an increase of 5% for Dentosal Friskt Tandkött. and an increase of 2% for placebo. A significant difference in the plaque levels (p<0.05) was found between Colgate Paradent and Pepsodent Gum Health and between Colgate Paradent and placebo. The gingival bleeding index was improved in all 4 groups. A significant difference (p<0.05) was found with respect to bleeding between Colgate Paradent and placebo (p<0.05) at the 3-month registration. A statistically significant increase over time in total number of streptococci and total colony forming units were found for the Dentosal, Pepsodent and placebo groups, but not for Colgate. To conclude, this study seems to verify that a dentifrice containing a combination of triclosan and copolymer is effective in reducing supra-gingival plaque formation and gingival bleeding without causing major shifts in the salivary microflora.     

Effectiveness of a triclosan/copolymer dentifrice on dental plaque and gingivitis in Brazilian individuais with cerebral palsy

This randomized clinicai trial investigated the effect of a dentifrice containing triclosan on the reduction of dental plaque and gingivitis in institutionalized individuais with cerebral palsy. Fifty-seven residents were randomly allocated to a test group (n=28, dentifrice with triclosan) and a control group (n=29. conventional dentifrice). A single calibrated investigator performed examinations at baseline and after three months. The amount of dental plaque was assessed, and gingivitis was meas-ured. The caretakers performed brushing with dentifrice. After three months, there was a significant reduction in the plaque index in both groups, but there was no difference between the two groups. There was a significant reduction in gingivitis only in the test group, and the difference between groups was significant after three months. The authors concluded that the dentifrice with triclosan reduced interdental bleeding in the studied population.     

The effect of triclosan on developing gingivitis

Abstract The aim of the study was to examine whether triclosan has an effect on developing gingival inflammation. 10 volunteers, with clinically healthy gingivae were enrolled. The study was performed as a 2-week, double-blind, crossover, experimental gingivitis trial. Between each plaque accumulation period, there was a wash-out phase of 4 weeks. A baseline examination was performed which included assessment of plaque and gingivitis. The volunteers were asked to refrain from mechanical oral hygiene measures for 2 weeks. During this period, they rinsed 2× daily with one of the randomly assigned mouthrinse preparations. Solution A (period A): 0.06% triclosan + 2%tween 80. Solution B (period B): 0.06% triclosan +0.25% sodium lauryl sulphate. Re-examinations were performed on days 4, 7, 11 and 14. The mean plaque score increased during period A to 2.2 (day 4), 2.8 (day 7), 3.1 (day 11) and 3.1 (day 14). The corresponding scores for period B were significantly lower; 1.2 (day 4), 1.8 (day 7), 2.0 (day 11) and 2.2 (day 14). The mean gingivitis scores at baseline were 0.17 (periods A and B). The mean gingivitis scores increased to 0.45 (day 4), 0.69 (day 7), 0.83 (day 11) and 0.96 (day 14) when the subjects rinsed with solution A and 0.42 (day 4), 0.64 (day 7), 0.78 (day 11) and 0.92 (day 14) in period B. There were no statistically significant differences between periods A and B with respect to gingivitis. Thus, although significantly more plaque formed during period A than period B, no differences could be found between the gingivitis scores in the 2 periods.     

The effect of delmopinol rinsing on dental plaque formation and gingivitis healing

The aim of this study was to investigate a possible dose-response effect of delmopinol hydrochloride, on the development of plaque and on the healing of gingivitis. 64 healthy male volunteers, aged 18-40 years with healthy gingivae and clean teeth, participated. During a 2-week period, the participants refrained from all oral hygiene and rinsed 2x daily with a placebo solution. On day 14 of the study, they received professional toothcleaning, and were randomly assigned to 4 groups. For the following 2 weeks, they rinsed 2x daily for 1 min with 10 ml of 0.05% (15 subjects), 0.1% (17) or 0.2% (16) delmopinol, respectively. 16 subjects rinsed with 0.2% chlorhexidine. No oral hygiene procedures were performed during the test period. On days 0, 14 and 28, gingival bleeding index and the presence of stainable plaque were determined. Periodic identical photographs were used for planimetric determination of buccal plaque extension. No significant difference for the reduction in gingival bleeding index was found between 0.2% delmopinol and chlorhexidine rinsing. The mean plaque index showed its most significant reduction on lingual surfaces of both upper and lower jaws when rinsing with 0.2% delmopinol. Mean plaque extension was reduced by 23% for 0.05%, 39% for 0.1% and 55% for 0.2% delmopinol. A significant dose-response effect for 0.05%, 0.1% and 0.2% delmopinol was found for gingival bleeding index, plaque index and plaque extension. The results show that delmopinol favors the healing of gingivitis and reduces plaque formation.     

The effect of herbal extracts in an experimental mouthrinse on established plaque and gingivitis

Abstract. The purpose of the present study was to establish in vitro the inhibiting effect of a herbal extract mixture on a selected number of micro-organisms and to test in vivo the effect of a mouthwash containing 6.3 mg/ml herbal extract mixture on plaque and gingivitis as compared to a minus active control mouthrinse. The herbal extract was a mixture of: Juniperus communis (juniper), Urtica dioca (nettle), Achillaea millefolium (yarrow); 1:1:1. In the study, in-vitro, the effect of pure herbal extract mixture on acid production of Streptococcus mutans was tested and the minimum inhibitory concentrations (MIC) of the following micro-organisms were tested: Streptococcus mutans, Streptococcus mitis, Actynomyces viscosus, Actynomyces naeslundii, Actinobacillus actinomycetemcomitans, Prevotella intermedia, Campylobacter rectus, Fusobacterium nucleatum, Veillonella parvula. The MIC-values for A. viscosus and P. gingivalis were 100 mg/ml. The MIC-values for A. naeslundii and A. actinomycetemcomitans were considerably lower (10 mg/ml). S. mitis was the most susceptible of the tested organisms to the extract with a MIC value of 1 mg/ml. S. mutans, C. rectus, V. parvula, and F. nucleatum were not influenced by the extracts. No inhibitory effect of the 6.3 mg/ml herbal extract mixture was observed on the acid production of S. mutans. For the study in-vivo, 45 volunteers were selected on the basis of having moderate gingival inflammation. As efficacy parameters the plaque index, modified gingival index and angulated bleeding index were assessed. The subjects were randomly divided among 3 experimental groups (2× test and 1‘minus active’control). The participants were requested to rinse with 10 ml of mouthwash twice a day for a period of three months. After 6 weeks and 3 months, the same clinical indices as at baseline were recorded. The results show no difference between the two test groups and the control group. In conclusion, the results of the present study have shown that the mixture of the 3 herbal extracts, Juniperus communis, Urtica dioca and Achillaea millefolium when used in a mouthrinse has no effect on plaque growth and gingival health.     

The effects of a dentifrice containing a zinc salt and a non-cationic antimicrobial agent on plaque and gingivitis

The antiplaque potential of metal salts in mouthwashes or dentifrices has been previously demonstrated. The purpose of the present investigation was to establish the effects on plaque and gingival health of a dentifrice which contained a combination of the metal salt, zinc citrate, and the anti-microbial agent, Triclosan. Plaque growth was reduced by a dentifrice which contained either zinc citrate or triclosan, but greater inhibition was achieved with dentifrices which contained both agents. A 4-day non-brushing study in which slurries of the dentifrice were used, confirmed that the test dentifrice which contained 1% zinc citrate and 0.5% Triclosan reduced the accumulation of plaque by 50%. In a double-blind crossover study of 28 days duration, a significant reduction in plaque accumulation and an improvement in gingival health was demonstrated for the test dentifrice compared to the placebo. Further analysis of the data indicated that the dentifrice was most efficacious for participants who brushed ineffectively. Also, the greatest benefit was obtained by subjects that used the largest amount of dentifrice.     

Comparison of the effect of toothpastes containing enzymes or antimicrobial compounds with a conventional fluoride toothpaste on the development of plaque and gingivitis

Many toothpastes have been formulated over recent years to contain antimicrobial compounds with the aim of preventing or reducing plaque, calculus, gingival inflammation or dental caries. For many, if not all of these toothpastes, it has yet to be proven whether they are significantly better at reducing plaque and gingivitis than conventional toothpastes, for which no such therapeutic effects have been claimed. This 12-day, incomplete block designed, cross-over study compared the development of plaque and gingivitis following rinsing with toothpaste slurries containing the following active ingredients: (1) hexetidine/zinc citrate, (2) 0.2% triclosan, (3) amyloglucosidase/glucose oxidase, (4) sodium fluoride/sodium monofluorophosphate (NaF, MFP). By the 8th day of the study, a significant difference in gingival crevicular fluid (GCF) and GI was found between the groups. By day 12, however, no significant difference in plaque index and gingival inflammation was found between the 4 toothpastes, although plaque area was significantly reduced with the hexetidine/zinc citrate paste when compared to the conventional fluoride paste. It was concluded that the active ingredients added to the toothpastes evaluated in this study provided little or no more additional benefit to oral hygiene and gingival health than could be achieved with a conventional fluoride toothpaste.     

Longitudinal clinical studies with antimicrobial mouthrinses

This chapter examines the use of long-term clinical studies to evaluate the effectiveness of antimicrobial mouthrinses in the prevention and/or treatment of plaque and gingivitis. Such studies should be double-blind, compare the active agent to a control, and last a minimum of 6 months. Such a time interval simulates a common recall interval, enables one to utilize a thorough dental prophylaxis at the initiation of the study, and is sufficient time to observe the development of toxic and other side-effects of therapy. The microbiological component should estimate plaque quantitatively and demonstrate that no pathogenic, opportunistic or resistant micro organisms develop. The indices and microbiology should be performed at baseline, and intermediate period and at 6 months. Thus far, published studies meeting these criteria support the efficacy of listerine and chlorhexidine as agents useful in reducing plaque and gingivitis. Preliminary evidence indicates that sanguinarine may also be effective. The most common side effect of listerine was the complaint of poor taste. Increased stain and calculus formation were cited as the most significant side-effects of chlorhexidine. Such side-effects must be taken into consideration when recommending effective antimicrobial mouthrinses for patient use.     

一种香精油漱口水抑制菌斑和牙龈炎症作用的研究

目的评价一种香精油漱口水抑制菌斑和牙龈炎症的作用。方法将67名改良牙龈指数(MGI)≥1.5且改良菌斑指数(MPI)≥2.0的受试者纳入试验,指导其在每天早晚刷牙后含漱20ml香精油漱口水30s,持续13周之后,检查受试者的MGI、MPI和牙龈出血指数(GBI),与基线值进行比较。结果使用香精油漱口水13周之后,与基线值相比,受试者的MGI下降了26.52%,MPI下降了61%,GBI下降了30.65%,差异均有显著性(P<0.01)。结论在日常刷牙的同时,配合使用香精油漱口水能够抑制菌斑和牙龈炎症。     

Chemotherapeutic inhibition of supragingival dental plaque and gingivitis development

Abstract A 6-month double-blind, controlled clinical study was conducted on 107 healthy adult subjects to determine the efficacy of a mouthrinse used as a supplement to regular oral hygiene measures on supragingival dental plaque and gingivitis. 115 healthy adult patients were recruited for the study. Following screening examinations for minimal entry levels of existing gingivitis and plaque in patients with a minimum of 20 sound natural teeth, extrinsic tooth stain, gingivitis and plaque index scores were recorded. Soft tissues were evaluated. All subjects then received a complete dental prophylaxis, removing plaque, calculus and extrinsic stain. Utilizing their normal oral hygiene, subjects began a regimen of rinsing with 20 ml of the randomly assigned rinse, twice daily for 30 s for 6 months. 7 days after prophylaxis, gingivitis was again scored (baseline 2). Soft tissue, gingivitis, plaque area and extrinsic stain were evaluated again at 3 and 6 months. Results demonstrated that after 6 months, listerine produced a 34% inhibition of both plaque and of gingivitis compared to a hydroalcohol control (p<0.001).     

A dose-response study of triclosan mouthrinses on plaque regrowth

Abstract Triciosan is used in toothpastes and mouthrinses as a plaque inhibitory agent. The concentrations used and therefore the dose of triclosan varies between products and there is, as with most plaque inhibitory agents, little information on the dose response of this agent. The purpose of this investigation was to measure the plaque inhibitory properties of triclosan in a simple mouthrinse formulation over a range of concentrations and therefore doses. The study was a 5 treatment, double-blind, Latin-square randomised, minus-active controlled design balanced for residual effects. The formulations were 0.01%, 0.05%, 0.1% and 0.2% triclosan in 0.5% sodium carbonate and 5% alcohol aqueous solutions, used as 10 ml, 1-min rinses 2 x daily, without tooth-brushing. 2 groups each of 15 healthy volunteers rinsed during alternate 4-day treatment, 1-week washout periods with the allocated rinses. From a zero-plaque baseline on Day 1, plaque was scored by index and area on Day 5. A dose response pattern of decreasing plaque indices and particularly areas, with increasing triclosan dose was observed. However, by far the largest sequential drop in plaque scores occurred between 0.1% and 0.2% triclosan treatments. Extending the dose-response study to higher concentrations is considered impractical if not unjustifiable, because of potential harmful local side-effects and compliance difficulties. Dose–response studies to assess the agents thought to potentiate triclosan would seem warranted.     

Microbiological and clinical effects of a dentifrice containing zinc citrate and Triclosan in the human experimental gingivitis model

A partial mouth experimental gingivitis model was employed to establish the effect of a dentifrice containing 0.2% Triclosan and 0.5% zinc citrate on the development of chronic gingivitis. In addition, changes in the plaque flora associated with the developing gingivitis have been monitored. Following a period of stringent oral hygiene, volunteers were allocated to 1 of 2 treatment groups. A toothshield was constructed to fit 4 posterior mandibular teeth. During the 21-day experimental period test or placebo dentifrice was applied to the experimental teeth via the tooth shield. The toothshield also prevented plaque removal from those teeth during habitual brushing of the remaining dentition. Supragingival plaque was collected at baseline and day 21 for analysis of the total bacterial flora. At the end of the experimental period, plaque and gingivitis had developed in both groups. However, the test group had significantly less plaque and gingivitis than the placebo group. The microbiological data demonstrated that plaque from the test group contained significantly lower numbers of anaerobes compared to plaque from the placebo group. This was considered particularly significant as these bacteria are generally associated with chronic inflammatory periodontal disease. There was also a trend for the numbers of actinomyces to decrease in plaque from the test group but not in the placebo group.     

The effects of antimicrobial mouthrinses on de novo plaque formation at sites with healthy and inflamed gingivae

Abstract The objective of the present investigation was to evaluate to what extent mouthrinses containing triclosan and chlorhexidine may modify the amount of de novo plaque that forms on tooth surfaces adjacent to healthy and inflamed gingival units. 10 volunteers were recruited. On day 0, gingival crevicular fluid (GCF) was obtained at predetermined sites and gingivitis (GI) was assessed. A careful oral profylaxis was given to each of the volunteers who subsequently abstained from all mechanical plaque control measures for the following 18 days. During the first 4 days (rinse phase I), they rinsed with either 0.12% chlorhexidine. 0.06% triclosan or placebo solution. Clinical examinations (GCF, GI) were repeated and the amount of plaque formed determined on days 4, 7 and 14. On day 14, the participants received a new professional tooth cleaning after which rinse phase II was initiated. During this 2nd phase, the participants rinsed for 4 days with the same mouthwash preparation and in the same manner as during rinse phase I. The examinations were repeated on day 18. Each participant received a comprehensive oral prophylaxisis and was instructed to perform meticulous mechanical plaque control during the following 4 weeks. A 2nd experimental period was then initiated. A total of 3 experimental periods were repeated until all subjects had rinsed with the 3 different mouthwash preparations. The results demonstrated (i) that significantly more plaque formed at sites with gingivitis than at surfaces adjacent to healthy gingival units and (ii) pre-existing gingivitis significantly increased the amount of de novo plaque that formed in subjects who rinsed with mouthwash preparations containing chlorhexidine and triclosan.