Studies on stannous fluoride toothpaste and gel (2). Effects on salivary bacterial counts and plaque regrowth in vivo

Structural characterization of tin in toothpaste by dynamic nuclear polarization enhanced 119Sn solid-state NMR spectroscopy

Stannous fluoride (SnF2) is an effective fluoride source and antimicrobial agent that is widely used in commercial toothpaste formulations. The antimicrobial activity of SnF2 is partly attributed to the presence of Sn(II) ions. However, it is challenging to directly determine the Sn speciation and oxidation state within commercially available toothpaste products due to the low weight loading of SnF2 (0.454 wt% SnF2, 0.34 wt% Sn) and the amorphous, semi-solid nature of the toothpaste. Here, we show that dynamic nuclear polarization (DNP) enables 119Sn solid-state NMR experiments that can probe the Sn speciation within commercially available toothpaste. Solid-state NMR experiments on SnF2 and SnF4 show that 19F isotropic chemical shift and 119Sn chemical shift anisotropy (CSA) are highly sensitive to the Sn oxidation state. DNP-enhanced 119Sn magic-angle turning (MAT) 2D NMR spectra of toothpastes resolve Sn(II) and Sn(IV) by their 119Sn chemical shift tensor parameters. Fits of DNP-enhanced 1D 1H → 119Sn solid-state NMR spectra allow the populations of Sn(II) and Sn(IV) within the toothpastes to be estimated. This analysis reveals that three of the four commercially available toothpastes contained at least 80% Sn(II), whereas one of the toothpaste contained a significantly higher amount of Sn(IV).

Clinical trials evaluating desensitising agents. Some design and analysis issues

INTRODUCTION

The purpose of this short communication is to draw attention to an efficient design for trials to evaluate desensitising agents, and an appropriate statistical analysis.

METHODS

Two recent sensitivity trials conducted by the Bristol Dental School Clinical Trials Group are reviewed.

RESULTS

The methodology used was effective to establish efficacy of the products evaluated.

CONCLUSIONS

This methodology is recommended for wider use.

CLINICAL SIGNIFICANCE

Effective clinical trial methodology enables establishment of efficacy of desensitising products leading to patient benefit.

Characterising salivary peptidome across diurnal dynamics and variations induced by sampling procedures

OBJECTIVES

This study aimed to characterise diurnal dynamics of salivary peptidome and variations induced by sampling procedures.

MATERIALS AND METHODS

A supervised short-term longitudinal study was conducted amongst ten healthy participants. Saliva samples were collected by different procedures (stimulated/unstimulated conditions, forepart/midstream segments) on three consecutive days. The peptidome compositions of saliva samples were analysed using matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF MS).

RESULTS

The salivary peptidome exhibited a stable trend generally, even though some diurnal dynamics happened in aspects of both overall structure and certain single peptides. The results indicated saliva samples collected under unstimulated and stimulated conditions have significantly different structures of peptidome, whilst the peptidome profile of stimulated saliva was more abundant than that of unstimulated saliva. It was also indicated that the midstream segment effect might exist in the segmented process of saliva sampling.

CONCLUSIONS

In summary, salivary peptidome was able to maintain stability though some dynamic changes might happen within a short-term period. Stimulated and unstimulated saliva samples had significantly different peptidome profiles, whilst the stimulated whole saliva was a larger pool of low molecular weight peptides.

CLINICAL RELEVANCE

The stability of the salivary peptidome highlights the reliability of salivary peptidome as a source of diagnostic biomarker. We recommend keeping one collection condition (stimulated/unstimulated) consistently within one study on salivary peptidome. Stimulated whole saliva would be preferred if more abundant peptidome profile is needed.

Oral Health: Global Research Performance under Changing Regional Health Burdens

Objectives: Inadequate oral hygiene still leads to many serious diseases all over the world. Therefore, this study aimed to analyze scientific research in the field of oral health in order to be able to comprehend their relevant subject areas, research connections, or developments. Methods: This study aimed to assess the global publication output on oral hygiene to create a world map that provides background information on key players, trends, and incentives of research. For this purpose, established bibliometric parameters were combined with state-of-the-art visualization techniques. Results: This study shows the actual key players of research on oral hygiene in high-income economies with only marginal participation from lower economies. This still corresponds to the current burden situations, but they are more and more shifting to the disadvantage of the low-income countries. There is a clear North-South and West-East gradient, with the USA and the Western European nations being the most publishing nations on oral hygiene. As an emerging country, Brazil plays a role in the research. Conclusions: The scientific power players were concentrated in high-income countries. However, the changing epidemiological situation requires a different scientific approach to oral hygiene. This requires an expansion of the international network to meet the demands of future global oral health burdens, which are mainly related to oral hygiene.

Long-Term Use of Oral Hygiene Products Containing Stannous and Fluoride Ions: Effect on Viable Salivary Bacteria

The aim of this randomized, controlled clinical trial was to isolate and identify viable microorganisms in the saliva of study participants that continuously used a stannous and fluoride ion (F/Sn)-containing toothpaste and mouth rinse over a period of three years in comparison to a control group that used stannous ion free preparations (noF/Sn) over the same time period. Each group (F/Sn and noF/Sn) included 16 participants that used the respective oral hygiene products over a 36-month period. Stimulated saliva samples were collected at baseline (T0) and after 36 months (T1) from all participants for microbiological examination. The microbial composition of the samples was analyzed using culture technique, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and 16S rDNA Polymerase Chain Reaction (PCR). There were only minor differences between both groups when comparing the absolute values of viable microbiota and bacterial composition. The treatment with F/Sn led to a slight decrease in disease-associated and a slight increase in health-associated bacteria. It was shown that the use of stannous ions had no negative effects on physiological oral microbiota even after prolonged use. In fact, a stabilizing effect of the oral hygiene products containing stannous ions on the health-associated oral microbiota could be expected.

Influence of the long-term use of oral hygiene products containing stannous ions on the salivary microbiome - a randomized controlled trial

Oral hygiene products containing tin are suitable to prevent erosive tooth wear, yet effects on the oral microbiota are not known yet. Therefore, this study determined the salivary microbiome of 16 participants using products with stannous ions for three years (TG) compared with a control group (CG) to assess their influence on the microbiota. Participants were included in a randomized controlled clinical trial (RCT) with biannual visits. Illumina Miseq sequencing revealed as most abundant genera: Streptococcus (TG 14.3%; CG 13.0%), Veillonella (TG 11.3%; CG 10.9%), Prevotella (TG 7.0%; CG 9.8%), Haemophilus (TG 6.6%; CG 7.2%), Porphyromonas (TG 5.9%, CG 5.1%), Leptotrichia (TG 5.8%; CG 4.9%), Actinomyces (TG 4.0%; CG 4.6%) and Neisseria (TG 5.4%; CG 4.2%). Beta-Diversity was not significantly different between groups at both time points, although significant differences between groups were found for certain taxa after three years. The genus Prevotella was found in higher abundance in CG whereas Neisseria and Granulicatella, health-associated taxa, were found more abundantly in TG. Salivary microbiota after three years reflected a composition associated with oral health, hence continual use as a preventive measure for dental erosion can be considered safe and benefitting oral health for patients with a high risk of erosion.

Intraindividual Variation and Personal Specificity of Salivary Microbiota

Salivary microbiota is a typical habitat of the human microbiome. This study intended to use salivary microbiota as a model aiming to systematically address the influence of collection methods and temporal dynamics on the human microbiota compared to personal specificity. We carried out a supervised short-term longitudinal study to evaluate the influence of the change of collection methods and sampling time point on salivary microbiota in 10 systemically and orally healthy individuals with certain confounding factors (sex, oral and general health state, medication history, physical exercise, diet, and oral hygiene behavior) controlled before and during the sampling period. The microbial profiles were analyzed by 16S rDNA V3 to V4 hypervariable region amplicon sequencing. The taxonomic structure represented by the dominant species and the weighted UniFrac distance algorithm were used to demonstrate the individual specificity and the intraindividual variation introduced by the change of collection method and sampling time point. The findings suggested individual specificity existed in salivary microbiota from individuals with similar oral and general health status. The intraindividual variation brought by the change of collection method or sampling time point might introduce remarkable perturbation with the personal specificity. Insights into the intraindividual variation and personal specificity of salivary microbiota will enhance our understanding in salivary microbiota-related research. We recommend keeping collection conditions consistent within a study to avoid interference brought by the sampling. The strategy of repeated sampling at multiple time points as representative samples, as well as thorough interpretation of the complex relationships and causality between microbiome composition and disease without the interference of temporal dynamics, is optimal for research exploring the relationship between the salivary microbiome and disease.

Solving the problem with stannous fluoride: Formulation, stabilization, and antimicrobial action

BACKGROUND

Stannous fluoride (SnF₂) is a compound present in many commercially available dentifrices; however, oxidative decomposition negatively impacts its efficacy. Stannous oxidation is often mitigated through the addition of complexing agents or sources of sacrificial stannous compounds. The authors have found that the addition of zinc phosphate significantly improved stannous stability more effectively than other stabilization methods. The authors evaluated the chemical speciation of stannous compounds within a variety of formulations using x-ray absorption near edge spectroscopy (XANES), a technique never used before in this manner. These data were compared and correlated with several antimicrobial experiments.

METHODS

XANES data of various commercially available compounds and Colgate Total^SF were performed and analyzed against a library of reference compounds to determine the tin chemical speciation. The antibacterial assays used were salivary adenosine triphosphate, short-interval kill test, plaque glycolysis, and anaerobic biofilm models.

RESULTS

XANES spectra showed a diverse distribution of tin species and varying degrees of SnF₂ oxidation. In vitro antimicrobial assessment indicated significant differences in performance, which may be correlated to the differences in tin speciation and oxidation state.

CONCLUSIONS

Driven by the excipient ingredients, SnF₂ dentifrices contain a distribution of tin species in either the SnF₂ or Sn(IV) oxidation state. The addition of zinc phosphate provided significant robustness against oxidation, which directly translated to greater efficacy against bacteria.

PRACTICAL IMPLICATIONS

The choice of inactive ingredients in a dentifrice with active SnF₂ can dramatically impact product stability.

A review of topical therapy for skin infections with bacteria and yeast

BACKGROUND

Cutaneous infections with bacteria and yeasts are common in small animal practice. Treatment with systemic antibiotics or antifungal agents may not be ideal, because of the increasing development of multiresistant organisms, the cost and the possible adverse effects. Topical antimicrobials may be used as adjunctive therapy to systemic treatment or as sole therapy instead of systemic treatment.

OBJECTIVE

This literature review evaluated studies on topical antimicrobial treatment of skin infections.

METHODS

In vitro and in vivo studies evaluating topical antimicrobial agents were identified using a number of electronic and manual searches of textbooks and articles. Studies were evaluated, and the evidence for or against the use of the topical agents was extracted.

RESULTS

There is good evidence for the efficacy of chlorhexidine and, to a lesser degree, benzoyl peroxide in canine bacterial skin infections. There is limited evidence for the efficacy of silver sulfadiazine and medical honey against bacterial skin infections in the dog, and for the efficacy of hydrogen peroxide and stannous fluoride in the horse. Good evidence supports the use of a combination of chlorhexidine and miconazole in dogs with cutaneous Malassezia infections. There is insufficient evidence to recommend any other topical therapy for use in cutaneous infections.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although many antimicrobial topicals are marketed in veterinary dermatology, the efficacy has been reported for only a minority of agents. Randomized controlled trials evaluating various topical treatments are therefore urgently needed.

Evaluation of the specificity and effectiveness of selected oral hygiene actives in salivary biofilm microcosms

The microbiological effects of biocidal products used for the enhancement of oral hygiene relate to the active compound(s) as well as other formulation components. Here, we test the specificities of selected actives in the absence of multiple excipients. Salivary ecosystems were maintained in tissue culture plate-based hydroxyapatite disc models (HDMs) and modified drip-flow biofilm reactors (MDFRs). Test compounds stannous fluoride (SF), SDS, triclosan (TCS), zinc lactate (ZL) and ZL with SF in combination (ZLSF) were delivered to the HDMs once and four times daily for 6 days to MDFRs. Plaques were characterized by differential viable counting and PCR–denaturing gradient gel electrophoresis (DGGE). TCS and SDS were the most effective compounds against HDM plaques, significantly reducing total viable counts (P<0.05), whilst SF, ZL and ZLSF were comparatively ineffective. TCS exhibited specificity for streptococci (P<0.01) and Gram-negative anaerobes (P<0.01) following a single dosing and also on repeated dosing in MDFRs. In contrast to single exposures, multiple dosing with ZLSF also significantly reduced all bacterial groups, whilst SF and ZL caused significant but transient reductions. According to PCR–DGGE analyses, significant (P<0.05) reductions in eubacterial diversity occurred following 6 day dosing with both TCS and ZLSF. Concordance of MDFR eubacterial profiles with salivary inocula ranged between 58 and 97 %. TCS and ZL(SF) exhibited similar specificities to those reported for formulations. TCS was the most potent antibacterial, after single and multiple dosage regimens.

Polymerase chain reaction-based denaturing gradient gel electrophoresis in the evaluation of oral microbiota

BACKGROUND/AIMS

Clinical evaluation of oral microbial reduction after a standard prophylactic treatment has traditionally been based on bacterial cultivation methods. However, not all microbes in saliva or dental plaque can be cultivated. Polymerase chain reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) is a cultivation-independent molecular fingerprinting technique that allows the assessment of the predominant bacterial species present in the oral cavity. This study sought to evaluate the oral microbial changes that occurred after a standard prophylactic treatment with a conventional oral care product using PCR-DGGE.

METHODS

Twelve healthy adults participated in the study. Pooled plaque samples were collected at baseline, 24 h after prophylaxis (T1), and 4 days after toothbrushing with fluoride toothpaste (T4). The total microbial genomic DNA of the plaque was isolated. PCR was performed with a set of universal bacterial 16S rDNA primers. The PCR-amplified 16S rDNA fragments were separated by DGGE. The effects of the treatment and of dental brushing were assessed by comparing the PCR-DGGE fingerprinting profiles.

RESULTS

The mean numbers of detected PCR amplicons were 22.3 +/- 6.1 for the baseline group, 13.0 +/- 3.1 for the T1 group, and 13.5 +/- 4.3 for the T4 group; the differences among the three groups were statistically significant (P < 0.01). The study also found a significant difference in the mean similarities of microbial profiles between the baseline and the treatment groups (P < 0.001).

CONCLUSION

PCR-based DGGE has been shown to be an excellent means of rapidly and accurately assessing oral microbial changes in this clinical study.

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.

Comparative effects of different chlorhexidine mouth-rinse formulations on volatile sulphur compounds and salivary bacterial counts

AIM

To compare five different commercial mouth rinses with chlorhexidine (CHX) with respect to their anti-halitosis effect and anti-microbial activity on salivary bacterial counts, following a standardised research protocol. And secondly, to validate the study model proposed in the evaluation of patients suffering from halitosis.

PATIENTS AND METHODS

Ten volunteers, with a healthy oral status, were enrolled in a double-blind, cross-over design, using sterile saline as negative control and five CHX-containing mouth rinses: 0.12% CHX alone (CHX+NO), plus alcohol (CHX+ALC), plus 0.05% cetylpiridinium chloride (CHX+CPC), plus sodium fluoride (CHX+NaF), and 0.05% CHX plus 0.05% CPC, plus 0.14% zinc lactate (CHX+Zn). The levels of whole-mouth volatile sulphur compounds (VSCs) were measured by means of a sulphide monitor at baseline, 1 and 5 h after rinsing with the assigned product. Baseline measurements also included an organoleptic assessment and the recording of the tongue-coating index. Aerobic and anaerobic salivary bacterial counts were also obtained by collecting unstimulated saliva samples at the same evaluation times, and processed by culturing techniques. Analysis of variance was used to evaluate whether significant differences existed among groups, at each evaluation point, or in changes between evaluations.

RESULTS

No significant differences were detected at baseline, with VSC levels ranging between 190 and 227 parts per billion (p.p.b.) After rinsing, VSC levels were reduced with all products (except saline), after 1 h. Significant differences at 1 h were detected (p=0.04), corresponding to a lower amount of p.p.b. (109) in (CHX+Zn) as compared with the other groups (except CHX+NO). At 5 h, VSC levels were lower for CHX+CPC and CHX+Zn (155 and 169, respectively), while the other groups showed levels higher than 220 p.p.b. With respect to aerobic salivary bacterial counts, CHX+CPC demonstrated the lowest percentage of survival (6% after 1 h and 18% after 5 h). For anaerobic bacterial counts, again CHX+CPC demonstrated the lowest percentage of survival (10% at 1 h and 23% at 5 h), together with CHX+ALC (18% of survival at 5 h). However, salivary counts and VSCs were only significantly correlated at baseline, but not after treatment.

CONCLUSION

Important differences can be expected from different CHX formulations, in relation to both their anti-halitosis effect and anti-microbial activity in saliva. Formulations that combine CHX and CPC achieved the best results, and a formulation combining CHX with NaF resulted in the poorest.

A high molecular mass cranberry constituent reduces mutans streptococci level in saliva and inhibits in vitro adhesion to hydroxyapatite

Previous investigations showed that a high molecular mass, non-dialyzable material (NDM) from cranberries inhibits the adhesion of a number of bacterial species and prevents the co-aggregation of many oral bacterial pairs. In the present study we determined the effect of mouthwash supplemented with NDM on oral hygiene. Following 6 weeks of daily usage of cranberry-containing mouthwash by an experimental group (n = 29), we found that salivary mutans streptococci count as well as the total bacterial count were reduced significantly (ANOVA, P < 0.01) compared with those of the control (n = 30) using placebo mouthwash. No change in the plaque and gingival indices was observed. In vitro, the cranberry constituent inhibited the adhesion of Streptococcus sobrinus to saliva-coated hydroxyapatite. The data suggest that the ability to reduce mutans streptococci counts in vivo is due to the anti-adhesion activity of the cranberry constituent.

Differences in antimicrobial activity of four commercial 0.12% chlorhexidine mouthrinse formulations: an in vitro contact test and salivary bacterial counts study

AIM

To evaluate the in vitro and in vivo antimicrobial activity of four commercial 0.12% chlorhexidine mouthrinses.

MATERIAL AND METHODS

The in vitro antimicrobial activity test consisted in a modified contact test where 20 selected bacterial species were tested during 1 min with each test product. After the contact, the inoculum was cultured, and the results were expressed in terms of survival/resistance and the percentage of survival as compared to a saline control. The in vivo test consisted of a double-blind, randomized, crossover salivary bacterial counts study. 10 volunteers rinsed during 1 min with each tested product. Saliva samples were obtained before rinsing, and after 5 min, and 1, 3, 5 and 7 h. These samples were cultured both aerobically and anaerobically. Percentages of survival, in regard to baseline, were calculated for each time point. Comparisons among products were tested using anova and selected paired t-test.

RESULTS

The in vitro contact test showed no survival in any tested species with CHX+CPC, while three species (Lactobacillus casei, Streptococcus mitis and Peptostreptococcus micros) were resistant to the other three products. CHX and CHX+NaF demonstrated additional resistant species (three and four species, respectively). The in vivo salivary bacterial counts test showed higher reductions of CHX+CPC and CHX+ALC in aerobic and anaerobic bacteria, lasting for 5 h. Significant differences were detected at multiple time points, when these two products were compared both with the control and the other tested products.

CONCLUSION

Important differences in activity, among 0.12% CHX products, were detected by both in vitro and in vivo tests. The formulation with alcohol was more active than those without alcohol, excepting the formulation with CHX+CPC, in which the reformulation and addition of CPC not only compensate but rather increase the antimicrobial activity.

A modification to the experimental gingivitis protocol to compare the antiplaque properties of two toothpastes

BACKGROUND AND AIMS

Randomised, blind, controlled experimental gingivitis and home-use study protocols are used to evaluate the efficacy of oral hygiene products. The present methodological study combined the two clinical trial designs to compare the preventive and therapeutic potentials of two toothpastes.

MATERIAL AND METHODS

The study was a parallel group, randomised, double-blind design, initially involving 73 healthy dentate subjects. A 21-day experimental gingivitis protocol was combined with a 6-week (42 days) home-use protocol. At baseline, modified gingival index (MGI), gingival index (GI) and gingival bleeding (GB) were recorded. A dental prophylaxis was then performed. Subjects were allocated to either control fluoride or stannous fluoride toothpaste based on gender and GI. During the first 21-day period, subjects applied the allocated toothpaste, for 1 min twice a day, to a group of teeth in a plastic shield and brushed the remaining teeth with the same paste. From day 21 the shield was not placed, and subjects brushed all teeth with the toothpaste for 1 min twice per day up to day 42. MGI, GB and a plaque index (PI) were recorded on days 21 and 42.

RESULTS

Sixty-nine and 67 subjects completed to days 21 and 42, respectively. For shielded teeth, PI, MGI and GB increased to day 21 and then after ceasing the use of the shield decreased to day 42. At day 21, PI favoured the stannous fluoride toothpaste, but differences did not achieve statistical significance for any parameter at days 21 or 42. For unshielded teeth, there were no significant differences between the toothpastes for any parameter at either time point.

CONCLUSION

: The feasibility of combining two gingivitis clinical trial methodologies appears proven, and data on both the preventive and therapeutic chemical and mechanical efficacy of toothpastes can be obtained through such protocols. Specifically from the present study and consistent with some other reports, the plaque inhibitory properties of the stannous fluoride product are limited and do not always translate into an antiplaque/antigingivitis effect.

Substantivity of toothpaste slurries and their effect on reestablishment of the dental biofilm

OBJECTIVES

Toothpastes are good vehicles for antibacterial substances to exert a prolonged effect. This effect depends on the substantivity and ability to interfere with plaque metabolism and/or vitality. It was the purpose of this clinical, randomized 2 x 4 cell crossover study to evaluate and to compare the antibacterial effects of two toothpastes (Colgate Total(R), COL and Parodontax(R), PAR) applied as slurries on established plaque over 24 h (Part I) and their effect on 4-day plaque regrowth (Part II). Chlorhexamed(R) (0.1%; CHX) and water served as positive and negative controls.

MATERIAL AND METHODS

After professional toothcleaning eight students were asked to refrain from all mechanical hygiene measures for the next 72 h. After 48 h plaque was sampled and vitality of the plaque flora examined (baseline, VF0%). The subjects then rinsed for 1 min with 15 mL of one of the test or control solutions. Every second hour up to 14 h and 24 h after rinsing, plaque sampling and staining was performed to assess plaque vitality (VF2-24, Part I). In Part II, the classical 4-day plaque regrowth design was used with two rinses (1 min) a day as the only oral hygiene measure. Vitality values were assessed on day 1 and day 4 (VF1, VF2). At day 4, teeth were stained to assess the whole mouth plaque index (PlI) and to evaluate the percentage of plaque area (PA) of the anterior teeth.

RESULTS

Compared to placebo, all active rinses reduced plaque vitality significantly over a period of 24 h (Part I). PAR, COL and CHX revealed reductions of 18-31%, 28-50% and 19-50%, respectively. In Part II, similar reductions of all parameters were found for all active rinses (PAR 12-30%, COL 34-51%, CHX 40-64%).

CONCLUSIONS

Colgate Total has shown a significant action on plaque regrowth and a high substantivity during 24 h, while Parodontax revealed a more moderate but still significant effect.

The effect of a polyhexamethylene biguanide mouthrinse compared to an essential oil rinse and a chlorhexidine rinse on bacterial counts and 4-day plaque regrowth

OBJECTIVES

For various clinical applications, polyhexamethylene biguanide hydrochloride (PHMB) has been used for many years as an antiseptic in medicine. Recently, a 0.04% PHMB mouthwash was shown to inhibit plaque regrowth and to reduce oral bacterial counts. In this study, a 0.12% PHMB mouthrinse (A) was compared with a negative control placebo rinse (10% ethanol, flavour) (B), a positive control 0.12% chlorhexidine rinse (C), and a commercially available mouthrinse containing essential oils (Listerine) (D).

MATERIALS AND METHODS

The study was a double-blind, randomised 4-replicate 4 x 4 Latin square cross-over design in which plaque regrowth was measured. The in vivo antibacterial effect was assessed by taking bacterial counts from the tooth surface and mucosa 4 h after the first 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 Bonferroni HSD adjustment for multiple comparisons (significance level alpha=0.05).

RESULTS

The 0.12% PHMB mouthrinse (A) was significantly more effective in inhibiting plaque than the placebo (B) but no significant differences could be observed between A and 0.12% chlorhexidine (C), or between A and Listerine (D). Bacterial count reductions on the tooth surface with PHMB (A) were significantly greater compared to the placebo (B) after 4 h and significantly greater compared to B and D after 5 days. Chlorhexidine (C) was more effective than A after 5 days. On the mucosa, chlorhexidine (C) was significantly more effective in reducing bacterial counts than the other 3 treatments at both time points investigated. PHMB (A) was significantly more effective in reducing bacterial counts than the placebo (B) after 4 h and after 5 days, and than D after 4 h.

CONCLUSION

Consistent with a previous study, a PHMB mouthrinse was shown to inhibit plaque recolonisation and to reduce oral bacterial counts, indicating that PHMB may find applications in the prevention of plaque-associated diseases.

Evaluation of oral hygiene products: science is true; don't be misled by the facts

Most people in industrialized countries use oral hygiene products. When an oral health benefit is expected, it is important that sufficient scientific evidence exist to support such claims. Ideally, data should be cumulative derived from studies in vitro and in vivo. The data should be available to the profession for evaluation by publication in refereed scientific journals. Terms and phrases require clarification, and claims made by implication or derived by inference must be avoided. Similarity in products is not necessarily proof per se of efficacy. Studies in vitro and in vivo should follow the basic principles of scientific research. Studies must be ethical, avoid bias and be suitably controlled. A choice of controls will vary depending on whether an agent or a whole product is evaluated and the development stage of a formulation. Where appropriate, new products should be compared with products already available and used by the general public. Conformity with the guidelines for good clinical practice appears to be a useful way of validating studies and a valuable guide to the profession. Studies should be designed with sufficient power to detect statistically significant differences if these exist. However, consideration must be given to the clinical significance of statistically significant differences between formulations since these are not necessarily the same. Studies in vitro provide supportive data but extrapolation to clinical effect is difficult and even misleading, and such data should not stand alone as proof of efficacy of a product. Short-term studies in vivo provide useful information, particularly at the development stage. Ideally, however, products should be proved effective when used in the circumstances for which they are developed. Nevertheless, a variety of variable influence the outcome of home-use studies, and the influence of the variable cannot usually be calculated. Although rarely considered, the cost-benefit ratio of some oral hygiene products needs to be considered.