The effect of hexetidine 0.1% in the control of dental plaque

Parotid gland swelling following mouthrinse use

BACKGROUND

Unilateral or bilateral swelling of the parotid gland is a reported side effect of rinsing the mouth with chlorhexidine. Although the incidence rate is extremely low, there have been several case reports on this topic and the authors of these reports have suggested several explanations for the mechanism of this complication.

METHODS

In this report, two cases of parotid gland swelling are discussed. Both patients developed unilateral parotid swelling following the use of a mouthwash, case 1 after using a chlorhexidine mouthwash following flap surgery and case 2 after using a hexetidine mouthwash in an approved clinical trial that was testing different mouthwashes.

RESULTS

In both of the cases, differential diagnoses were made to explain the cause of the parotid swelling. However, discontinuing use of the product resulted in an eventual complete resolution of symptoms in both patients.

CONCLUSIONS

Swelling of the parotid gland following use of a mouthwash has previously been reported, although previous reports found this side effect only in patients who used chlorhexidine mouthwashes. This complication has therefore been informally linked to chlorhexidine. The present case report questions this hypothesis and suggests that parotid gland swelling may not be related to the type of mouthwash used, but may instead be a consequence of the rinsing action itself.

An in vitro oral biofilm model for comparing the efficacy of antimicrobial mouthrinses

The ability of commercial mouthrinses to reduce total viable counts of mixed microbial populations was examined using a previously developed in vitro model of supragingival plaque. Exploratory experiments aimed at fine-tuning the model indicated that optimal correspondence between in vitro and clinical results for chlorhexidine-containing formulations were obtained at a saliva:medium ratio of 70:30 (v/v); moreover, expanding the microbial population from 5 bacterial species to 5 bacterial species + Candida albicans had no noticeable impact on overall results. The efficacies of 12 different mouthrinse proprietary products containing chlorhexidine, hexetidine, octenidine, Triclosan, plant extracts, or aminefluoride/stannous fluoride vis-à-vis biofilm clearance were compared. All mouthrinses promoted a statistically significant reduction in microbial load compared to distilled water. The herbal- and phenolic-based products were substantially less effective than most chlorhexidine-containing mouthrinses, or mouthrinses containing hexetidine or octenidine. No significant difference between the plaque-clearing plaque-clearing abilities of Listerine and Meridol was observed. This polyspecies biofilm model can be a valuable tool for preclinical testing of antiplaque formulations, particularly during the product development stage.

The concomitant development of poly(vinyl chloride)-related biofilm and antimicrobial resistance in relation to ventilator-associated pneumonia

Ventilator-associated pneumonia is a major cause of death in intensive care patients and the endotracheal tube, commonly fabricated from poly(vinyl chloride) (PVC), is acknowledged as a significant factor in this. Bacteria colonise the biomaterial, thereby adopting a sessile mode of growth that progresses to the establishment of an antibiotic-resistant biofilm by the accretion of a protective glycocalyx. This study examined the sequential steps involved in the formation of biofilm on PVC by atomic force microscopy and the concomitant development of resistance to an antibiotic (ceftazidime) and to a non-antibiotic antimicrobial agent (hexetidine). Staphylococcus aureus and Pseudomonas aeruginosa isolated from ET tube biofilm were employed. The surface microrugosity of bacteria growing in sessile mode on PVC decreased significantly (p < 0.05) over the period 4, 24, 48 h and 5 d. The progressive accretion of bacterial glycocalyx was readily visualised in micrographs leading to a smoother surface topography with time. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for ceftazidime and hexetidine against planktonic (suspension) S. aureus were lower than for Ps. aeruginosa. Furthermore, sessile populations of S. aureus and Ps. aeruginosa on PVC exhibited greater resistance to both ceftazidime and hexetidine when compared to planktonic bacterial growth. The efficacy of the agents, determined by kill kinetics, against sessile bacteria was dependent on age, with established biofilms (> or = 24 h) significantly more resistant (p < 0.05) than early sessile populations (< or = 4 h). Importantly, for practice, even newly colonised bacteria (1 h) were significantly more resistant to antibiotic than planktonic bacteria. Hexetidine was significantly more active (p < 0.05) than ceftazidime on biofilms of both isolates, irrespective of age, with total kill within 24 h treatment. Hexetidine may offer promise in the resolution of infection associated with PVC endotracheal tubes.

Determination of the salivary retention of hexetidine in-vivo by high-performance liquid chromatography

The non-antibiotic antimicrobial agent hexetidine is widely used at a concentration of 0.1% w/v as an oral rinse to reduce the number of viable microorganisms within the oral cavity. However, following use, the available concentration of hexetidine in the oral cavity declines with time, thus compromising the resultant antimicrobial activity. It is, therefore, desirable to determine the persistence of the agent in the oral cavity by quantification of the drug concentration in saliva, thus enabling prediction of its antimicrobial activity in the oral environment. A rapid reverse-phase HPLC method was therefore developed and validated for hexetidine in aqueous solution (Oraldene) and in saliva samples collected from volunteers post-rinsing with 15 mL of hexetidine oral rinse for 30s. The HPLC assay was sufficiently sensitive to accurately detect hexetidine in saliva up to 25 min after in-vivo use of a commercial oral rinse. Furthermore, it was possible to detect hexetidine below the published minimum inhibitory concentrations (MICs) for a selection of microorganisms. From these data a first-order elimination rate constant of hexetidine from the oral cavity was determined post-rinsing in each of six volunteers. The validated HPLC assay method presented is useful for the assay of hexetidine in the oral cavity both at and below MICs. The first-order elimination rate constant shows significant variation between volunteers.

The effects of hexetidine (Oraldene) on the adherence of Candida albicans to human buccal epithelial cells in vitro and ex vivo and on in vitro morphogenesis

PURPOSE

This study reports the effects of hexetidine (Oraldene) on two virulence attributes of Candida albicans, namely, in vitro and ex vivo adherence of yeast cells to buccal epithelial cells (BEC) and in vitro morphogenesis.

METHODS

The effects of hexetidine treatment of either yeast cells (stationary and exponential phases) or BEC on Candidal adherence, in terms of viable and non-viable adherent yeast cells, were evaluated using an acridine orange stain in conjunction with fluorescence microscopy. Ex vivo anti-adherence effects were determined by rinsing BEC in vivo with hexetidine (0.1%), removal of BEC after defined periods and inclusion in the adherence assay. The effects of hexetidine on morphogenesis were evaluated using light microscopy. Yeast cell viability following exposure to a range of concentration of hexetidine (0.005-0.1% v/v) for defined periods was determined following serial dilution and enumeration on solid media.

RESULTS

Treatment of stationary and exponential phase yeast cells or BEC with hexetidine (0.1%) for a range of times (10-300 s) or, alternatively, with a range of concentrations of hexetidine (0.005-0.1%) for a fixed time (30s) significantly decreased the resultant Candidal/ epithelial adhesion. No correlations were observed between reduced adherence and either time of treatment or hexetidine concentration. In vivo treatment of BEC with hexetidine (0.1%) for 30s resulted in prolonged and significant reductions in the ex vivo adherence of both viable and non-viable yeast cells for periods of up to (and including) four hours post-rinsing. Treatment of C. albicans blastospores with hexetidine (0.05, 0.1% v/v) for 10s and 30s totally inhibited Candida morphogenesis, whereas treatment with lower antiseptic concentrations significantly reduced the extent of Candida morphogenesis and the rate of hyphal development. The effects of hexetidine on yeast cell viability were both concentration and time-dependent.

CONCLUSIONS

The reduced adherence of C. albicans to BEC and the modification or inhibition of morphogenesis following exposure to hexetidine suggests a clinical role for hexetidine in the prophylaxis of both superficial candidosis and the systemic complications resulting from invasion of sub-epithelial tissue.

Mouthrinses

Mouthrinses have been used for centuries for medicinal and cosmetic purposes, but it is only in recent years that the rationale behind the use of the ingredients has been subject to scientific research and clinical trials. Although Listerine held its position for many years in the vanguard of the anti-plaque agents, the advent of mouthrinses containing chlorhexidine was a major breakthrough in the research for a chemical means to prevent disease. Since that time, and especially in the past ten years, the number of formulations that claim to have anti-plaque, anti-calculus, and anti-caries activity has increased, and much emphasis has been placed on such substances as an adjunct to, or indeed to replace, conventional toothbrushing techniques. This review covers the literature on mouthrinses over the past five years, concentrating more on the anti-plaque, anti-gingivitis, and anti-calculus formulations. In the first section, the methods of conducting clinical trials of mouthrinses are discussed, and a plea is made for a greater degree of standardization of methodology with agreed acceptable levels of clinical benefit. Trials of established mouthrinses are considered, and the advantages and disadvantages of several newer formulations discussed. From the review, it appears that chlorhexidine has no equal in its effects on reduction of plaque and gingivitis, but major drawbacks lie in the taste and stain-producing problems. The pre-brushing rinse, Plax, does not have unqualified success in all trials, though the more recent European formulation may have promise. Newer rinses which inhibit bacterial adhesion to tooth surfaces also appear promising, and it is suggested that more work on combinations of active ingredients is necessary.

Antibacterial dentifrices. Clinical data and relevance with emphasis on zinc/triclosan

The present review concerns the effect on plaque and gingivitis of some antibacterial dentifrices. The difficulties of including cationic agents in conventional dentifrice formulations are briefly discussed. The focus is on 2 recently introduced dentifrices with triclosan as the active ingredient. One aims at providing a slow release reservoir of triclosan in the oral cavity by delivering the substance dissolved in a lipophilic copolymer. 3-month results indicate a modestly improved effect on plaque and gingivitis compared to that of triclosan alone. Long-term studies are needed before conclusions on the clinical relevance can be drawn. The other dentifrice on the market utilises the principle of additive effects by combining triclosan and zinc citrate in the formulation. The combination appears to be more effective against plaque and gingivitis than either compound alone. Studies of up to 1 year duration indicate that the level of oral hygiene and gingival health obtained through an initial period of motivation and oral hygiene instruction can be maintained by regular use of the test dentifrice, while most subjects in the control group returned to pre-experimental levels. Microbiological monitoring indicates no major shifts in plaque ecology nor any development of resistant bacteria, and adverse side-effects have not been observed. It is concluded that the new approaches to chemical plaque control may be beneficial to the population at large, and thus of great clinical relevance.