Pharmacological control of periodontal disease. I. Antiplaque agents

Chemical plaque control - A brief review

Dental plaque is a complex microbial population of bacterial and salivary polymers present on the tooth surface. It is understood that human diseases must be avoided and a high social concern for the population as a whole. The argument for the implementation of successful prevention measures is strong for life-threatening diseases or those with serious morbidity. However, regardless of seriousness, the case for avoiding any disease may be based on the belief that it is easier to be healthy than dead or sick. Thus plaque prevention is an efficient way to both treat and avoid periodontal diseases, it is an important component of gingival and periodontal diseases' primary management.

Characterization and antimicrobial effect of a bioinspired thymol coating formed on titanium surface by one-step immersion treatment

OBJECTIVE

To develop an antimicrobial and anti-adherent thymol (TOH)-containing coating on titanium (Ti) by a bioinspired one-step biocompatible method.

METHODS

A nanolayer of adsorbed TOH (TOH-NL-Ti) was formed by an easy deep coating method on Ti surface. The treatment consists in a simple one-step immersion process in a TOH-containing solution. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), potentiodynamic electrochemical technique, open circuit potential records, Atomic Force Microscopy (AFM) and measurements of TOH release were used to characterize TOH-NL-Ti. Live/Dead staining and plate counting were employed to quantify attached and living adhered bacteria, respectively. Biocompatibility and cytotoxicity in fibroblastic and pre-osteoblastic cell lines were evaluated by acridine orange staining and MTT assay, respectively.

RESULTS

TOH adsorbed on TOH-NL-Ti was detected by ATR-FTIR and electrochemical techniques. ATR-FTIR results showed that TOH nanofilms development involves spontaneous production of ketonic structures on Ti surface. AFM analysis revealed that the thickness of the TOH-NL was below 80 nm. Finally, microbiological assays confirmed that TOH-NL-Ti can inhibit the adhesion and kill attached bacteria leading to the eradication of leaving cells on its surface. After 24 h of biocidal release, the antimicrobial effect is also significant (a decrease of 3 orders in the number of attached bacteria).

SIGNIFICANCE

The formation of TOH-NL-Ti nanolayer is a simple strategy able to be applied by not specially trained personnel, to reduce implant infection risks, ensure highly effective antimicrobial action and inhibition of bacterial adhesion on Ti surfaces without showing toxic effects for pre-osteoblastic and fibroblastic cells.

Potential of chitosan-based carrier for periodontal drug delivery

Periodontal diseases are chronic infectious diseases and are a major oral health burden. With the progress in the understanding of etiology, epidemiology and pathogenesis of periodontal diseases coupled with the understanding of the polymicrobial synergy in the dysbiotic oral microbial flora, several new therapeutic targets have been identified. The strategies to curb bacterial growth and production of factors that gradually destroy the tissue surrounding and supporting the teeth have been the cornerstone for inhibiting periodontitis. Systemic administration of antibiotics for the treatment of periodontitis have shown several drawbacks including: inadequate antibiotic concentration at the site of the periodontal pocket, a rapid decline of the plasma antibiotic concentration to sub-therapeutic levels, the development of microbial resistance due to sub-therapeutic drug levels and peak-plasma antibiotic concentrations which may be associated with various side effects. These obvious disadvantages have evoked an interest in the development of localized drug delivery systems that can provide an effective concentration of antibiotic at the periodontal site for the duration of the treatment with minimal side effects. A targeted sustained release device which could be inserted in the periodontal pocket and prolong the therapeutic levels at the site of action at a much lower dose is the need of the hour. Chitosan, a deacetylated derivative of chitin has attracted considerable attention owing to its special properties including antimicrobial efficacy, biodegradability, biocompatibility and non-toxicity. It also has the propensity to act as hydrating agent and display tissue healing and osteoinducting effect. The aim of this review is to shine a spotlight on the chitosan based devices developed for drug delivery application in the effective treatment of various periodontal disorders. The chitosan based carriers like fibers, films, sponge, microparticles, nanoparticles, gels that have been designed for sustained release of drug into the periodontal pocket are highlighted.

Can we add chlorhexidine into glass ionomer cements for band cementation?

OBJECTIVE

To test if the addition of chlorhexidine digluconate (CHD) might influence the mechanical properties and antibacterial properties of two different conventional glass ionomer cements (GICs) used for band cementation.

MATERIALS AND METHODS

Two commercial brands of conventional GICs were used: Ketac Cem Easymix (3M/ESPE, St Paul, Minn) and Meron (Voco, Cuxhaven, Germany). The cements were manipulated in their original composition and also with 10% and 18% CHD in the liquid to create a total of six groups. Diametral tensile strength, compressive strength, microhardness, shear bond strength, and antibacterial effects in 5, 45, and 65 days against Streptococcus mutans were tested in all groups, and the data were submitted to statistical analyses.

RESULTS

There were no significant differences between the groups of the same material in diametral tensile, compressive strength, and shear bond strength (P > .05). There was significant improvement in the microhardness to the Ketac Cem Easymix (P < .001). GICs with the addition of CHD showed significant inhibition of S. mutans growth in comparison with the control groups at the three time points evaluated (P < .001). The addition of 18% CHD resulted in higher bacterial inhibition (P < .001).

CONCLUSIONS

The addition of chlorhexidine digluconate to conventional GICs does not negatively modify the mechanical properties and may increase the antibacterial effects around the GICs even for relatively long periods of time.

In vitro effects of a fraction separated from Polygonum cuspidatum root on the viability, in suspension and biofilms, and biofilm formation of mutans streptococci

Polygonum cuspidatum (Polygonaceae) has traditionally been used in folk medicine to control oral diseases. Nevertheless, there are no reports related to its possible effect on the diseases, particularly on biofilm-related diseases such as dental caries. In this study, we evaluated in vitro effects of a fraction separated from Polygonum cuspidatum root on the viability, in both suspension and biofilms, and the biofilm formation of mutans streptococci. The separated fraction (F1) showed bacteriostatic and bactericidal activity against mutans streptococci in suspension, with minimum inhibitory concentration (MIC) range of 31.3-250 microg/ml and minimum bactericidal concentration (MBC) range of 0.5-1 mg/ml. At a concentration of 1.5 mg/ml, F1 killed approximately 2 log(10)CFU/ml of Streptococcus mutans and Streptococcus sobrinus after 2h of exposure. In biofilms, F1 also inhibited the viability of Streptococcus mutans and Streptococcus sobrinus, dependent on the biofilm age, the concentration of F1, and the treatment time. Four hours of exposure to 1.5 mg/ml F1 reduced the viable counts of Streptococcus mutans and Streptococcus sobrinus by greater than 2 log(10)CFU/disc. Furthermore, at sub-MIC levels, F1 inhibited biofilm formation by Streptococcus mutans and Streptococcus sobrinus in a dose-dependent fashion. Based on the preliminary phytochemical analysis, the activity of F1 may be related to the presence of anthraquinones, cardiac glycosides, terpenoids, and phenolics. These results indicate that F1 is probably useful in the control of oral biofilms and subsequent dental caries development.

Effect of aqueous extract from Neem (Azadirachta indica A. Juss) on hydrophobicity, biofilm formation and adhesion in composite resin by Candida albicans

OBJECTIVE

Azadirachta indica, a Meliaceae family tree, has been used in India for many years in the treatment of several diseases in medicine and dentistry. Current research analyses the effects of the leaf aqueous extract from Azadirachta indica (Neem) on the adhesion, cell surface hydrophobicity and biofilm formation, which may affect the colonisation by Candida albicans.

METHODS

Azadirachta indica extract was tested in vitro on strains of Candida albicans 12A and 156B. Changes in hydrophobicity were reported in assays of yeast adhesion to hydrocarbons, in biofilm formation with glucose and in the adhesion of the microorganisms on light cured composite resin. Assays involved enumeration of candidal colony-forming units together with scintillation counting of radiolabelled Candida and compared to a solution of chlorhexidine digluconate 0.125% widely used in dentistry.

RESULTS

Yeast growth in Neem extract was not inhibited in concentrations ranging from 0.1mg/ml. A statistically significant increase (p<0.05) in cell surface hydrophobicity was evident for the two strain tested and there was also an associated increase in biofilm formation after contact with Neem extract in concentration 0.01 g/ml. Decrease in adhesion capacity of cells to composite resin was also recorded.

CONCLUSION

An anti-adhesive mechanism of action by Azadirachta indica is proposed based on the results observed.

How to select the right mouthrinses in periodontal prevention and therapy. Part I. Test systems and clinical investigations

The use of mouthrinses is increasing, especially as adjuncts to the daily mechanical oral hygiene. Different test systems may and can be used to test their antibacterial and clinical effects: bacteriology in vitro, substantivity in vivo, 4-day plaque re-growth, experimental gingivitis and long-term use. The plaque re-growth investigations of a few days are not only of limited use but may also be dangerous because often too extensive conclusions have been drawn from their design. The 'gold standard' test is the experimental gingivitis model to reveal the antiplaque as well as the antigingivitis effects of any mouthrinse preparation during 3 weeks. The last kind of investigations are of several months' duration, where the substances are used as supplements to mechanical oral hygiene measures.

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.

Chlorhexidine-modified glass ionomer for band cementation? An in vitro study

OBJECTIVE

To compare the mean retentive strength, predominant site of band failure, amount of cement remaining on the tooth at deband and survival time of orthodontic micro-etched bands cemented with chlorhexidine-modified (CHXGIC) or conventional glass ionomer cement (GIC).

DESIGN

In vitro study.

SETTING

Dental Materials Laboratory.

MATERIALS AND METHODS

One-hundred-and-twenty intact, caries-free third molars were collected from patients attending for third molar surgery. These were stored for 3 months in distilled water and decontaminated in 0.5% chloramine. To assess retentive strength, 80 teeth were randomly selected and 40 were banded with each cement. Testing was undertaken using a Nene M3000 testing machine at a cross-head speed of 1 mm/min. Following debanding, the predominant site of failure was recorded as cement-enamel or cement-band interface. The amount of cement remaining on the tooth surface following deband was assessed and coded. Survival time for another 40 banded specimens, 20 cemented with each cement, was assessed following application of mechanical stress in a ball mill.

MAIN OUTCOME MEASURES

Retentive strength, predominant site of failure, amount of cement remaining on the tooth surface, survival time.

RESULTS

Mean retentive strength for bands cemented with CHXGIC (0.32 MPa, SD 0.09) or GIC (0.28 MPa, SD 0.07) did not differ significantly (p=0.05). All bands failed at the enamel-cement interface. There was no significant difference in the amount of cement remaining on the tooth surface after deband for each cement type (p=0.23). The mean survival time of bands cemented with CHXGIC or GIC was 7.0 and 6.4 hours, respectively (p=0.23).

CONCLUSIONS

There was no significant difference in mean retentive strength, amount of cement remaining on the tooth after deband or mean survival time of bands cemented with CHXGIC or GIC. Bands cemented with either cement failed predominantly at the enamel-cement interface. The results suggest that CHXGIC may have comparable clinical performance to GIC for band cementation.

A comparison of the plaque-inhibitory properties of stannous fluoride and low-concentration chlorhexidine mouthrinses

BACKGROUND

Plaque inhibition by chlorhexidine (CHX) rinses is dose related with a relatively flat dose-response curve above 5-6 mg twice daily. Low dose regimens could therefore reduce local side effects but maintain reasonable efficacy.

AIMS

To compare the plaque inhibitory properties of two low-dose CHX rinse products with more conventional levels delivered from proprietary rinses. A secondary outcome was a comparison with a stannous fluoride/amine fluoride (SFAF) rinse product.

METHODS

The study was a five-treatments, negative controlled, randomised, single blind crossover design balanced for residual effects, involving 20 healthy subjects in a 24-h plaque re-growth model. On day 1 of each study period, subjects were rendered plaque free, suspended tooth cleaning and followed the appropriate rinse regimen. On day 2, subjects were scored for plaque by index and area. The rinse codes and rinsing regimens were: (A) 15 mg CHX 2 x daily for 30 s (0.1% CHX), (B) 9 mg CHX 2 x daily for 60 s (0.06% CHX), (C) 10 ml SFAF rinse 1 x daily for 30 s, (D) 15 ml placebo 2 x daily for 60 s, and (E) 6 mg CHX 2 x daily for 30 s (0.06% CHX).

RESULTS

Average mouth plaque indices and areas were highly significantly different between rinsing regimens. All test rinses were significantly more effective than the placebo rinse. There was a mean dose-response pattern for the CHX rinses, but there were no statistically significant differences between any of the test rinses.

CONCLUSIONS

Lower doses of chlorhexidine in rinses can be used to exert plaque inhibition comparable with products used at higher doses and equivalent to benchmark products such as the SFAF rinse. However, the availability of chlorhexidine from formulations has to be considered as in part explaining the results.

Buccoadhesive erodible disk for treatment of oro-dental infections: design and characterisation

Buccoadhesive erodible disks of cetylpyridinium chloride were prepared using different bioadhesive polymers along with excipients like mannitol. The purpose of designing the erodible disk was to obviate the need for removal of exhausted device. The optimized disk containing 5.0 mg of cetylpyridinium chloride, 2.0 mg of magnesium stearate and 6.0 mg of mannitol along with sodium carboxy methyl cellulose DVP and hydroxypropylmethylcellulose K4M in the ratio of 1:3 was found to release the drug for a period of over 6.0 h without getting dislodged. Maximum in vitro drug release was found to be 94.78% in 6.0-h study. In situ release characteristics were evaluated using a 'flow-through assembly', which simulated the conditions of the human buccal cavity. The drug concentrations in the in situ samples were found to be above minimum inhibitory concentration (MIC) of the drug. The bioadhesive performance and the surface pH of the disks were satisfactory. Cetylpyridinium chloride disks were tested against microorganisms commonly found in oro-dental infections namely Candida albicans, Staphylococcus aureus, Escherichia coli and Streptococcus mutans. The disk as well as the in situ samples showed inhibition of growth of microorganisms. Approval was taken from Jamia Hamdard Review Board (Ethical Board) to perform in vivo studies in healthy human volunteers. In vivo evaluation of buccoadhesive disks revealed adequate comfort, taste, and non-irritation and none of the volunteers reported severe dry mouth/severe salivation or heaviness at the place of attachment. Salivary concentrations were maintained above MIC for 8.0 h. Correlation was found between the drug concentration in situ and concentration of drug in saliva collected in healthy human volunteers. The correlation was found to be positive with a correlation coefficient of 0.9596. It was found to be statistically significant at 5% confidence level (P<0.05).

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.

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.

Effects of SCN-/H2O2 combinations in dentifrices on plaque and gingivitis

OBJECTIVES

A 10-week, double-blind, placebo-controlled clinical study on 140 male subjects was conducted to determine the effect on plaque and gingivitis of 5 dentifrices containing various thiocyanate (SCN-)/hydrogen peroxide (H2O2) combinations.

MATERIALS AND METHODS

The dentifrices consisted of a gel base without any detergents or abrasives (placebo, group A) to which SCN- and/or H2O2 were added as follows: 0.1% SCN- (group B), 0.5% SCN- (group C), 0.1% SCN-/0.1% H2O2 (group D), 0.5% SCN-/0.1% H2O2 (group E) and 0.1% H2O2 (group F). A baseline examination was performed in which the Silness and Löe Plaque Index (PI), the Mühlemann and Son Sulcus Bleeding Index (SBI), and the amount of gingival crevicular fluid (GCF) were recorded using the Periotron 6,000 on teeth 16, 12, 24, 36, 32, and 44. The subjects were randomly assigned to either the placebo group (n = 40) or one of the test groups (n = 20) and used their respective dentifrices over a period of 8 weeks. Finally, each group used the placebo for another 2 weeks (wash-out). Re-examinations were performed after 1, 4, and 8 weeks and the 2-week wash-out period employing the clinical parameters used at baseline. Intragroup changes were analyzed with the Wilcoxon signed-ranks test, using the baseline and wash-out points as references. The Mann-Whitney U test was used for comparisons between the treatment groups and the placebo group.

RESULTS

At the 8-week examination, the plaque index in group E (p = 0.017) and group F (p = 0.032) was lower than in the placebo group. The Sulcus Bleeding Index in group F after 1 week was increased (p = 0.023) and the SBI in group E after 8 weeks was reduced (p = 0.047) as compared to the placebo group.

CONCLUSION

The results demonstrated that a dentifrice containing 0.5% SCN- and 0.1% H2O2 but no detergents or abrasives inhibited plaque and decreased gingivitis.