Effect of food preservatives on in situ biofilm formation.

Department of Operative Dentistry and Periodontology, Dental School and Hospital, University Medical Center, Freiburg, Germany.
Clinical Oral Investigations (Impact Factor: 2.2). 03/2008; 12(3):203-8. DOI: 10.1007/s00784-008-0188-6
Source: PubMed

ABSTRACT The aim of this double-blind, controlled crossover study was to evaluate the influence of food preservatives on in situ dental biofilm growth. Twenty-four volunteers wore appliances with six specimens each of bovine enamel to build up intra-oral biofilms. During three test cycles, the subjects had to put one half of the appliance twice a day in one of the assigned active solutions (0.1% benzoate, BA; 0.1% sorbate, SA or 0.2% chlorhexidine, CHX) and the other into NaCl. After 5 days, the developed biofilms were stained with two fluorescent dyes to visualise vital (green) and dead bacteria (red). Biofilms were scanned by confocal laser scanning microscopy and biofilm thickness (BT) and bacterial vitality (BV%) were calculated. After a washout period of 7 days, a new test cycle was started. The use of SA, BA and CHX resulted in a significantly reduced BT and BV compared to NaCl (p<0.001). Differences between SA and BA were not significant (p>0.05) for both parameters, while CHX showed significantly lower values. Both preservatives showed antibacterial and plaque-inhibiting properties, but not to the extent of CHX. The biofilm model enabled the examination of undisturbed oral biofilm formation influenced by antibacterial components under clinical conditions.

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    ABSTRACT: Fluorescence illumination and observation is one of the most rapidly expanding microscopy techniques employed today, both in medical and biological sciences. Fluorescence-based microscopy offers several advantages over conventional optical and electronic microscopies, owing to sample fixing not being required and the possibility of observing bacterial vitality in live samples. However, it also has some disadvantages, such as the lower resolution power and the dependence on different dyes that, in some cases, may produce a bias in the vitality quantification. The use of fluorescent dyes is compulsory in fluorescence-based microscopy. There is a wide variety of different combinations of dyes, depending on what is being studied, thus they can be used for multiple purposes, such as cell labeling or bacterial-vitality identification. The latter is very useful in the study of oral biofilms and its susceptibility to determinate antimicrobial agents, whereas cell labeling using fluorescent in situ hybridization (FISH) with different fluorochromes allows the analysis of the bacterial topography of the oral biofilm. Fluorescence techniques used in combination with microscopy have considerably overcome some restrictions of traditional plate-culture techniques, although they show also some limitations, such as controversy over their reliability when assessing different bacterial states. For this reason, it has been stated that the measurements of bacterial vitality performed using these techniques should be compared with other molecular and microbiological techniques, and complemented with other microscopy techniques. In the present chapter, a detailed presentation of the methodology used for the determination of bacterial vitality in a "non-disturbed" oral biofilm (PL-biofilm) will be shown. The results of the evaluation of a PL-biofilm after 2 and 4 days by confocal laser scanning microscopy (CLSM) combined with a fluorescence solution will be presented in terms of bacterial vitality, thickness, covering grade and biofilm architecture, complementing them with the scanning electron microscopy (SEM) analysis.
    Microscopy: advances in scientific research and education, Edited by A. Méndez-Vilas, 09/2014: chapter Fluorescence Microscopy: pages 226-238; Formatex Research Center., ISBN: 978-84-942134-3-4
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    ABSTRACT: The scientific community considers that the analysis of undisturbed human plaque-like biofilm (PL-biofilm), using confocal laser scanning microscopy (CLSM), is the most suitable approach to the study of the in situ of PL-biofilm. Although some evidence on the structural characteristics of in situ early PL-biofilm has been described, there are few studies on the antibacterial effects of agents on this microbial structure. A major application of advanced microbiological and/or microscopy techniques, in combination with CLSM, needs to be exploited in future research in order to increase knowledge of the global characterisation of in situ PL-biofilms, as well as of the antibacterial effects of agents frequently used in Dentistry on biofilm structure.
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    ABSTRACT: Chlorhexidine (CHX) is the oral antiseptic par excellence. One of its principal advantages, in addition to its powerful antimicrobial action, is its ability to bind to a variety of substrates while maintaining its antibacterial activity; it is then slowly released, leading to the persistence of effective concentrations. This property is called substantivity. The purpose of this chapter is to review the findings published in the literature on the in situ antimicrobial activity of CHX in different oral ecosystems and to report our own results in this field. Numerous authors have demonstrated the immediate antibacterial effect of CHX and its substantivity in saliva for a minimum of 7 hours after a single mouthrinse. However, few authors have studied the in situ antibacterial activity of CHX on the salivary flora, analysing the influence of intrinsic factors associated with the antiseptic and extrinsic factors, all of which can affect its antibacterial activity. Nor have many studies been published using confocal laser scanning microscopy (CLSM) in association with bacterial viability techniques to determine the effects of CHX on in situ undisturbed plaque-like biofilm, and the results have not been uniform. Consequently, a more extensive application of advanced microbiological and/or microscopy techniques in combination with CLSM is required in future research in order to increase our understanding of the antibacterial effects of CHX and other antimicrobial agents on plaque-like biofilm structure. These effects should then be compared with the effects observed in other oral ecosystems (such as salivary flora) and the influence of intrinsic and extrinsic factors on the effectiveness of the antiseptic should be analysed.
    Science against microbial pathogens: communicating current research and technological advances, Edited by A. Méndez-Vilas, 12/2011: chapter Clinical microbiology: pages 530-541; Formatex Research Center., ISBN: 978-84-939843-1-1


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