Effects of 1% chlorhexidine gel treatment on sympathetic adrenergic nerves in human buccal mucosa

The effect of treatment with a commercially available 1% chlorhexidine gel (Hibitane Dental) in custom trays for 14 days (10 min daily) on the sympathetic adrenergic nerves in biopsies from human buccal mucosa was investigated. Chemical assay of endogenous noradrenaline concentration and immunocytochemical demonstration of tyrosine hydroxylase served as markers for structural and functional integrity of the adrenergic nerves. The mean concentration of noradrenaline in chlorhexidine treated tissues did not differ from the mean concentration in control. No morphologic or fluorescence intensity differences of the tyrosine hydroxylase immunoreactivity were found in the chlorhexidine treated tissues when compared to controls. These findings indicate that a relatively intense treatment with a commercially available 1% chlorhexidine gel does not affect the adrenergic innervation of human buccal mucosa.     

Gingival and mucosal reactions after intensive chlorhexidine gel treatment with or without oral hygiene measures

The aim of this study was to elucidate whether soft tissue reactions during chlorhexidine (CHX) treatment might be associated with meticulous oral hygiene measures. A commercially available 1% chlorhexidine digluconate gel (Hibitane Dental Gel) was applied in a custom tray for the mandibular arch, 10 min daily, for 14 days. A split mouth approach was used to allow evaluation of the effect of oral hygiene measures with toothbrush, toothpaste, and dental floss on one side of the arch. During the treatment period, 8 out of 12 subjects developed gingival and/or mucosal reactions appearing as white patches or ulcerations. Both the gingival reactions on the buccal marginal gingiva and the mucosal reactions near the margin of the custom tray occurred only when the gel treatment was combined with meticulous oral hygiene measures. The white patches, which could easily be detached, leaving ulcerated areas, consisted entirely of stratified squamous epithelium. The findings suggest that intensive treatment with chlorhexidine gel, in individually fitted custom trays, combined with meticulous oral hygiene measures may induce toxic effects on the surface layers of the gingiva and mucosa.     

Gingival and mucosal reactions after intensive chlorhexidine gel treatment with or without oral hygiene measures

Abstract – The aim of this study was to elucidate whether soft tissue reactions during chlorhexidine (CHX) treatment might be associated with meticulous oral hygiene measures. A commercially available 1% chlorhexidine digluconate gel (Hibitane Dental Gel) was applied in a custom tray for the mandibular arch, 10 min daily, for 14 days. A split mouth approach was used to allow evaluation of the effect of oral hygiene measures with toothbrush, toothpaste, and dental floss on one side of the arch. During the treatment period, 8 out of 12 subjects developed gingival and/or mucosal reactions appearing as white patches or ulcerations. Both the gingival reactions on the buccal marginal gingiva and the mucosal reactions near the margin of the custom tray occurred only when the gel treatment was combined with meticulous oral hygiene measures. The white patches, which could easily be detached, leaving ulcerated areas, consisted entirely of stratified squamous epithelium. The findings suggest that intensive treatment with chlorhexidine gel, in individually fitted custom trays, combined with meticulous oral hygiene measures may induce toxic effects on the surface layers of the gingiva and mucosa.     

Chlorhexidine gel and Steradent employed in cleaning dentures.

It was the purpose of the study to test the efficacy of brushing with a 1% chlorhexidine gel or a commercial solution cleanser (Steradent) in preventing formation of plaque on the fitting surface of new dentures. The study group consisted of 74 denture wearers with denture stomatitis who were assigned randomly to one of four treatment groups, testing either the chlorhexidine gel, a placebo gel, Steradent, or a placebo solution. The experiment was started immediately after denture treatment was completed. The experimental period was 1 month. The amount of denture plaque, the clinical condition of the palatal mucosa, and the concentration of yeasts in mucosal and denture smears were recorded while the patients used their original dentures and after the experimental period. Plaque had formed on all new dentures but to a smaller extent in the groups testing the chlorhexidine gel or the placebo gel. The study does not provide any obvious evidence of a chemical effect of chlorhexidine gel or Steradent as a means to prevent formation of microbial plaque on the mucosal surface of maxillary complete dentures.     

The effect of 1% chlorhexidine gel delivered with toothpicks on proximal dental plaque. A pilot study.

The aim of this study was to determine the effect of 1% chlorhexidine gel delivered with toothpicks on interproximal dental plaque. Seven follow-up patients participated in two treatment periods of 1 week each, separated by a normal oral hygiene period of one week. The study had double-blind design. The plaque index by Silness and L?e (Acta Odontol Scand 22: 121-135, 1964) was scored on mesial, distal, buccal and lingual surfaces of each tooth after plaque disclosure, with an aqueous solution of erythrosine and the measurements were performed by the same examiner, at the initial visit and at the end of every experimental week. The ability to use toothpicks was checked and upgraded to the individual need. The participants were instructed to carry out their normal oral hygiene procedures, with placebo gel or 1% chlorhexidine gel delivered interproximally with toothpicks once daily. No significant differences in the measurement of plaque were noted between placebo gel and 1% chlorhexidine gel at interproximal areas. After treatment with 1% chlorhexidine gel, the mean distribution of plaque score 0 was increased significantly (P < 0.05), from 30.7 sites (52%) to 42 sites (71.1%) when all sites are taken into account and compared to the placebo period. 1% Chlorhexidine gel delivered by toothpick on interproximal areas had a limited effect on reduction of dental plaque.     

Monitoring of buccal epithelial cells by alkaline comet assay (single cell gel electrophoresis technique) in cytogenetic evaluation of chlorhexidine

During the last few years, there has been increasing interest in buccal epithelial cells for cytogenetic evaluation of different materials. In the present study, the use of these cells and peripheral lymphocytes for cytogenetic evaluation of chlorhexidine digluconate (CHX) with comet assay (single cell gel electrophoresis, or SCGE) is reported. This technique detects DNA strand breaks in individual cells in alkaline conditions. Thirteen volunteers were requested to rinse their mouths with 0.12% CHX solution for 18 days. Buccal epithelial cells and peripheral blood lymphocytes were obtained from all participants at baseline and the end of the experimental period. One hundred cells per subject were analysed for the DNA damage. A statistical increase was observed in the damaged buccal and blood cells after the CHX application. The mean grade of damage in buccal cells was statistically different from that in blood cells. Due to minimal absorption of chlorhexidine into the tissues and low concentrations of free chlorhexidine in the oral cavity, the DNA damage produced by chlorhexidine in lymphocytes was lower than in buccal epithelial cells. As chlorhexidine does not accumulate in the body, the frequencies of DNA damage could be transient. Detected DNA damage after CHX use might be the indication of an earlier effect, before DNA repair begins, and could be reversible.     

The effect of a polyhexamethylene biguanide mouthrinse compared with a triclosan rinse and a chlorhexidine rinse on bacterial counts and 4-day plaque re-growth

OBJECTIVES: For various clinical applications, polyhexamethylene biguanide hydrochloride (PHMB) has been used for many years as an antiseptic in medicine. Recently, a 0.04% and a 0.12% PHMB mouthwash were shown to inhibit plaque re-growth and to reduce oral bacterial counts. In this study, a 0.2% PHMB mouthrinse (A) was compared with a positive control 0.12% aqueous chlorhexidine solution (B), a commercially available 0.3% triclosan/2.0% polyvinyl methyl ether maleic acid copolymer mouthrinse (Colgate Total Plax) (C), and a negative control placebo rinse (10% ethanol, flavour) (D). MATERIALS AND METHODS: The controlled clinical study was a double blind, randomized, four replicate cross - over design. Plaque re-growth was assessed with the Turesky et al. (1970) modification of the Quigley & Hein (1962) plaque index. The antibacterial effect was assessed by taking bacterial counts on the tooth surface (smears from the buccal surface of 16/26) and mucosa (smears from the buccal mucosa in opposite of area 16/26) after the professional prophylaxis and after the first rinse with the preparations on day 1 and prior to the clinical examination on day 5. Sixteen volunteers participated and, on day 1 of each study period were rendered plaque-free, ceased toothcleaning, and rinsed twice daily with the allocated mouthrinse. On day 5, plaque was scored and smears were collected according to the protocol. A 10-day wash-out period was carried out between each rinse evaluation. Data were analysed using ancova with Bonferroni HSD adjustment for multiple comparisons (colony forming units per sample) with a significance level alpha=0.05. RESULTS: The 0.2% PHMB mouthrinse (A) was significantly better at inhibiting plaque than the placebo (D), but significant less effective than the 0.12% aqueous chlorhexidine solution (B). There is no significant difference between A and the 0.3% triclosan/2.0% copolymer mouthrinse (C). Bacterial count reductions (tooth surface and mucosa) with PHMB (A) were significantly greater compared with the placebo (D) and triclosan (C), but significantly lower compared with chlorhexidine (B) (tooth surface) and equally effective compared with chlorhexidine (B) (mucosa). CONCLUSION: Consistent with previous studies, a PHMB mouthrinse was shown to inhibit plaque re-growth and to reduce oral bacterial counts, indicating that PHMB could be an alternative to established mouthrinses in preventive applications.     

The effect of two different dental gels and a mouthwash on plaque and gingival scores: a six-week clinical study

AIM: To evaluate the clinical efficacy of two gel formulations containing chlorhexidine gluconate and neem extract with a commercially available chlorhexidine gluconate mouthwash. METHOD: An open labelled randomised six-week clinical study with parallel group design in 48 subjects divided into four groups. Plaque accumulation and gingival condition were recorded using plaque index and gingival index. On the basis of mean baseline plaque and gingival scores, subjects were allocated to four different groups, using their assigned products twice a day, before bed and after breakfast. Plaque and gingival scores were recorded after three and six weeks. RESULTS: Mean plaque and gingival scores were reduced over the six-week trial period for experimental and control groups. Chlorhexidine gluconate gel reduced the plaque and gingival scores significantly more (p<0.05) than the chlorhexidine gluconate mouthwash. Neem extract gel also showed significant (p<0,05) reduction in plaque and gingival scores when compared with the control group. But there was no significant difference between the groups treated with chlorhexidine gel and neem extract gel. CONCLUSION: The results of this clinical study indicate that better therapeutic efficacy can be achieved using gels for treating oral infections than conventional treatments using mouthwash.     

Recolonization of human tooth surfaces by Streptococcus mutans after suppression by chlorhexidine treatment

In eight subjects who were initially highly colonized with Streptococcus mutans and who used a 1% chlorhexidine gel, the numbers of this organism were suppressed in both plaque and saliva. Bacterial plaque samples were obtained from all tooth surfaces, and the recolonization pattern of S. mutans was studied over a 26-week period. At baseline, 83% of all surfaces harbored S. mutans with buccal surfaces colonized in higher frequency than the others. After chlorhexidine treatment, the proportion of tooth surfaces colonized by S. mutans was reduced to a low level. Re-appearance was slow. S. mutans was first recovered from the most posterior teeth in the mouth, the molar surfaces were recolonized earlier than were those of pre-molars and anterior teeth, and the buccal surfaces were recolonized more readily than were the other tooth surfaces. The data show that there is a specific recolonization pattern of S. mutans after chlorhexidine treatment, and that the re-emergence of S. mutans is most probably due to regrowth of bacteria which have not been eradicated.     

Effect of professional flossing with chlorhexidine gel on approximal caries in 12- to 15-year-old schoolchildren

The aim of the investigation was to evaluate the effect of chlorhexidine gel treatment on caries development of approximal tooth surfaces and on salivary counts of Streptococcus mutans. 220 12-year-old schoolchildren, divided into three groups, participated: (1) chlorhexidine gel group (n = 72), (2) placebo gel group (n = 77), and (3) control group (n = 71). The study was carried out double blind with respect to the two gel groups. Group 1 was treated 4 times/year with 1% chlorhexidine gel and group 2 with a placebo gel. Approximately 1 ml of gel was applied interdentally by means of a flat dental floss. The control group did not receive any gel treatment or flossing. Number of S. mutans in the saliva was estimated on five occasions during the study with the spatula method. After 3 years, the mean approximal caries increment, expressed as new DFS, was 2.50 in the chlorhexidine gel group and 4.30 in the placebo gel group (p less than 0.05). The corresponding figure in the control group was 5.25 (p less than 0.001 when compared to group 1). 44% of the children in the chlorhexidine gel group and 32% in the placebo gel group did not develop any new approximal caries lesion during the 3-year observation period compared to 18% in the control group (group 1-3 p less than 0.001; group 2-3 p less than 0.05). The number of new approximal fillings (FS) was 0.24 in the chlorhexidine gel group, 0.75 in the placebo gel group and 0.82 in the control group (group 1-3 p less than 0.01; group 2-3 p less than 0.05). There was no statistically significant difference between the groups with respect to numbers of S. mutans in saliva. However, there were more individuals with low numbers of S. mutans in the chlorhexidine gel group at the final examination compared to the baseline level (p less than 0.05).     

Microbial-associated oral lichenoid reactions

OBJECTIVE: The objective of the present study was to compare a new type of symptomatic lichenoid reaction, specifically located on the mucosal side of the lips, and associated with microorganisms, with a matched group presenting with reticular oral lichen planus (OLP) of the buccal mucosa. PATIENTS AND METHODS: The mean age for both groups was 66 years with a predominance of women (62%). The lichenoid reaction group (n = 25) presented with a reticular reaction pattern embracing various degrees of erythema. Patients presenting with OLP had similar lesions confined to the buccal mucosa but not on the mucosal side of the lips. RESULTS: In both groups, 80% were on any type of medication. However, 56% of the patients with lichenoid reactions medicated with more than three drugs compared with 29% (P < 0.05) in the OLP group. The former group more often used medicaments prescribed for cardiovascular diseases (48%vs 25%). Twenty-two of the patients with lichenoid reactions were treated with chlorhexidine. In 80% of these patients (n = 18), the lesions improved or completely healed, indicating a microbial association. CONCLUSION: Lichenoid reactions present on the mucosal side of the lips may be initiated by microbial plaque precipitated on the buccal surfaces of the anterior teeth.     

Short-term clinical effects of commercially available gel containing Acacia arabica: a randomized controlled clinical trial

Background:  Certain plants used in folk medicine serve as a source of therapeutic agent by having antimicrobial and other multi-potential effects. This prospective, randomized, placebo and positively controlled clinical trial was designed to evaluate the short-term clinical effects of a commercially available gel containing Acacia arabica in the reduction of plaque and gingival inflammation in subjects with gingivitis.
Methods:  Ninety subjects diagnosed with chronic generalized gingivitis were selected and randomly divided into three groups: Group I – placebo gel, Group II – gumtone gel and Group III – 1% chlorhexidine gel. Clinical evaluation was undertaken using the gingival index of Loe and Silness and the plaque index at baseline, 2 weeks, 4 weeks and 6 weeks. A subjective evaluation was undertaken by questionnaire.
Results:  Gumtone gel showed significant clinical improvement in gingival and plaque index scores as compared to a placebo gel. This improvement was comparable to 1% chlorhexidine gel. Unlike chlorhexidine gel, gumtone gel was not associated with any discolouration of teeth or unpleasant taste.
Conclusions:  Gumtone gel may be a useful herbal formulation for chemical plaque control agent and improvement in plaque and gingival status.     

The effects of chlorhexidine digluconate on human fibroblasts in vitro.

The drug chlorhexidine has been widely utilized as a wound antiseptic and oral antimicrobial rinse. There have been numerous reports on its safety as an oral rinse, but its effects on wound healing have been contradictory. The present study utilized human fibroblasts derived from skin and oral tissues to test the effects of chlorhexidine on viability, growth, collagen gel contractions, and total protein synthesis. Cells were exposed for an hour to 0.005% and 0.002% chlorhexidine and for 30 seconds to 0.12% chlorhexidine. Our results indicate that a 0.002% concentration of the drug shows minimal cytotoxicity, but is able to suppress cell division almost completely. Collagen gel contraction, as a model of wound contraction, was also severely affected by all of the concentrations of chlorhexidine used. Total protein synthesis was suppressed by chlorhexidine in collagen gel culture. The data support the hypothesis that chlorhexidine is highly cytotoxic to cells in vitro, but various cell functions such as proliferation, collagen gel contraction, and protein synthesis are affected to different degrees by the drug.     

Langerhans cell surface densities in rat oral mucosa and human buccal mucosa

We determined surface densities of Langerhans cells (LCs) in rat oral mucosa and human buccal mucosa by enumerating ATPase-positive dendritic cells in epithelial whole mounts. For the rat, mean surface densities per mm2 were 160 in anterior buccal mucosa, 640 in posterior buccal mucosa, 430 in the palate and 340 in the tongue. Human buccal mucosa showed a density of 890 cells per mm2. We conclude that LC densities in oral mucosa approximate those of external body sites, making them available in numbers sufficient to accomplish their postulated antigen-presenting functions.     

Comparative permeability of human vaginal and buccal mucosa to water

There is currently a resurgence of interest in the oral mucosa as a route for drug delivery. The relative scarcity of human oral mucosa for in vitro permeability studies, and the fact that vaginal mucosa is histologically similar and more abundant than the former, caused us to compare these 2 tissues with respect to their barrier properties to water. Specimens of fresh, clinically-healthy human vaginal and buccal mucosa from non-smokers were taken from excised tissue obtained during vaginal hysterectomies and various oral surgical procedures. Biopsies from each specimen were mounted in flow-through diffusion cells and their permeability to tritiated water determined using a continuous flow-through perfusion system. Specimens were examined histologically before and after permeability experiments and similarities between vaginal and buccal tissues verified. No statistically significant differences between mean steady state flux values (10–16 h) for vaginal and buccal mucosa. respectively, were found. Human vaginal mucosa is therefore as permeable as buccal mucosa to water, and these results warrant further investigation with other compounds to establish whether vaginal mucosa may be a useful model for buccal mucosa for drug permeability studies.     

Langerhans cell surface densities in rat oral mucosa and human buccal mucosa

We determined surface densities of Langerhans cells (LCs) in rat oral mucosa and human buccal mucosa by enumerating ATPase-positive dendritic cells in epithelial whole mounts. For the rat, mean surface densities per mm² were 160 in anterior buccal mucosa, 640 in posterior buccal mucosa, 430 in the palate and 340 in the tongue. Human buccal mucosa showed a density of 890 cells per mm². We conclude that LC densities in oral mucosa approximate those of external body sites, making them available in numbers sufficient to accomplish their postulated antigen-presenting functions.     

Chlorhexidine-induced changes to human gingival fibroblast collagen and non-collagen protein production

BACKGROUND: Chlorhexidine (CHX) has been used extensively as an adjunctive therapy in the treatment of periodontal disease. It is well known that chlorhexidine is toxic to bacteria, but recent evidence has suggested that chlorhexidine may also have deleterious effects on gingival fibroblast proliferation as well as collagen and non-collagen protein production in cell culture. The purpose of this study was to examine the effects of chlorhexidine on gingival fibroblast proliferation as well as collagen and non-collagen protein production in cell culture. METHODS: Human gingival fibroblasts were incubated in MEM containing chlorhexidine concentrations ranging from 1 microM to 1300 microM at 37 degrees C for 1, 5, or 15 minutes. Control cells received an equal volume of MEM without chlorhexidine for similar times at 37 degrees C. Following incubation, the media were removed, cells washed twice with MEM supplemented with 10% FBS, and fibroblasts in treatment and control groups were allowed to recover in the same media for 24 hours. RESULTS: In all strains, cellular proliferation was dependent on the concentration of solubilized chlorhexidine in cell culture but independent of the duration of chlorhexidine exposure. The average inhibitory concentration necessary to reduce cellular proliferation by 50% (ID50) was 222.1 microM. In regard to collagen and non-collagen protein production, fibroblasts exposed to chlorhexidine concentrations (1 microM) well below the ID50 had a 65% reduction in collagen production and a 57% reduction in noncollagen protein production. CONCLUSIONS: These results suggest that chlorhexidine will induce a dose dependent reduction in cellular proliferation and that concentrations of chlorhexidine that have little effect on cellular proliferation can significantly reduce both collagen and noncollagen protein production of human gingival fibroblasts in vitro. Hence, the introduction of commercially available concentrations (0.12%) or diluted commercial concentrations (as low as 0.00009%) of chlorhexidine to surgical sites for short periods of time prior to wound closure can conceivably have serious toxic effects on gingival fibroblasts and may negatively affect wound healing.     

The effect of 6-monthly application of 40% chlorhexidine varnish on the microflora and dental caries incidence in a population of children in Surinam

This study is aimed at determining whether a commercially available varnish, containing 40% chlorhexidine, is able to reduce the numbers of mutans streptococci and lactobacilli in saliva, in a moderately caries-active population in Surinam. 238 children, ages 13-14 years, were selected from different schools in Paramaribo, Surinam. From these children, total dental status was recorded and saliva samples were taken. At baseline and every 6 months, a 40% chlorhexidine varnish (EC40) was applied. The control group received a neutral gel that did not contain chlorhexidine. The numbers of salivary mutans streptococci and lactobacilli were calculated by standard methods, and the caries status was recorded every 12 months. The study lasted 30 months. The results indicate that chlorhexidine varnish did not decrease the numbers of cariogenic bacteria, nor did it decrease caries progression. Moreover, in this population with a low dental health care, children with lactobacilli present in the saliva above our detection level, the chlorhexidine varnish even tended to increase caries progression, possibly due to selection of aciduric and acidogenic oral bacterial species. We therefore conclude that 40% chlorhexidine varnish is not likely to decrease caries in children in a high-treatment-need population without treatment of the sources of infection.     

Diffusion of reduced arecoline and arecaidine through human vaginal and buccal mucosa

Because alkaloids from areca nut, arecoline and arecaidine, have been implicated in the development of oral submucous fibrosis, we determined their diffusion kinetics through human buccal and vaginal mucosa. Four clinically healthy vaginal mucosa specimens (mean patient age +/- standard deviation: 47 +/- 15 years; age range: 31-60 years) and 4 buccal mucosa specimens from 2 male patients and 2 female patients (mean patient age +/- standard deviation: 31 +/- 9 years; age range: 17-53 years) were obtained during surgery. In vitro flux rates of reduced arecoline and arecaidine (r-arecoline and r-arecaidine) were determined by use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t-test were used to determine steady state kinetics and flux differences over time intervals. Although statistically significant differences were observed between flux values for both alkaloids and tissues at certain time points, these were not considered to be of biological (clinical) significance. However, the flux rates across both mucosa of r-arecoline were significantly higher statistically than those of rarecaidine. The findings demonstrated the differences in the diffusion kinetics between r-arecoline and r-arecaidine across human buccal and vaginal mucosa, an observation that could be explained in terms of their ionisation characteristics. Additionally, the results obtained further support the hypothesis that human vaginal mucosa can be used as a model for buccal mucosa in studies of permeability to various chemical compounds.     

Effect of a polyhexamethylene biguanide mouthrinse on bacterial counts and plaque

OBJECTIVES: For various clinical applications, polyhexamethylene biguanide (PHMB) has been used for many years as an antiseptic in medicine. Little is known, however, of its antibacterial activity in the oral cavity and its ability to inhibit plaque formation. In this study, a 0.04% PHMB mouthrinse (A) was compared with a negative control placebo rinse (10% ethanol, flavour) (B) and 2 positive control chlorhexidine rinses, one of which was a 0.12% aqueous solution (C) and the other a commercially available mouthrinse (Skinsept mucosa) diluted to a chlorhexidine concentration of 0.12% (D). MATERIAL AND METHODS: The study was a double-blind, randomised 4-replicate 4 x 4 Latin square cross-over design. Plaque regrowth was assessed with the Turesky et al. modification of the Quigley and Hein plaque index. The in vivo antibacterial effect was assessed by taking bacterial counts from the tooth surface (smears from the lingual surface of 16) and mucosa (smears from the buccal mucosa) 4 h after the 1st rinse with the preparations on day 1 and prior to the clinical examination on day 5. 16 volunteers participated, and on day 1 of each study period were rendered plaque-free, ceased toothcleaning, and rinsed 2x daily with the allocated mouthrinse. On day 5, plaque was scored and smears were collected according to the protocol. Washout periods were 9 days. Data were analysed using ANOVA with Tukey HSD adjustment for multiple comparisons (significance level alpha=0.05). RESULTS: Mouthrinses A, C, and D were significantly more effective in inhibiting plaque than the placebo (B). Mouthrinse C was significantly better than mouthrinses A and D, while mouthrinses D and A were equally effective in inhibiting plaque. Bacterial count reductions on the tooth surface with mouthrinse C were significantly greater compared to mouthrinse A and the placebo (B). The reduction of bacterial counts on the mucosa with C was significantly greater than with A and B after 4 h and significantly greater than with A, B and D after 5 days. Mouthrinse A reduced bacteria on the mucosa significantly more effectively than the placebo (B) after 4 h and 5 days, while mouthrinse D was more effective than the placebo (B) after 4 h. CONCLUSION: The results indicate that a 0.04% PHMB mouthwash inhibits plaque regrowth and reduces oral bacterial counts, and may be used in preventive applications in the oral cavity.