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: 2.29). 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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    Inmaculada Tomás, N.Donos, I.Prada-López, V. Quintas, M. Álvarez-Fernández
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    ABSTRACT: The proven antimicrobial and anti-inflammatory activities of Essential Oils (EO) led, in 1879, to their combination with a phenolic based formula to reach a higher potential. This new product was called Listerine®. After that, it gradually acquired more importance as an oral antiseptic until nowadays, when it is considered the most popular phenolic compound used in the oral cavity. Due to this, the number of studies about its mechanism of action has been increasing, especially in the last decade. The antiseptic activity of EO comes from their hydrophobicity, which produces a disturbance in the bacterial membrane that affects diverse cellular compounds causing a cascade effect. One of the ideal characteristics that antiseptics must have is the ability to adhere to the substrate and persist at effective concentrations, which is called substantivity. The purpose of this chapter is to review the previously published studies about the in situ antibacterial activity and substantivity of the EO in different oral micro-niches, as well as presenting our own results in this field. Up to now, there have been no papers published comparing the EO antibacterial activity with that of chlorhexidine (CHX) –the Gold-standard- after a single application, and there are only few cases in which the immediate antibacterial activity of the EO was evaluated. Thus, there are some published papers about the substantivity of EO in the saliva, which concluded that these last ones kept lower bacterial vitality levels than the negative control between 1-5 hours after their application; nevertheless, there are few papers which have studied the in situ antibacterial activity of the EO on structured biofilm and, in those cases, their application was performed ex vivo. What is common to most of the papers is the using of the Confocal Laser Scanning Microscope (CLSM) technique combined with a staining solution. This is due to its consideration as an effective technique when analysing both the structure and the bacterial viability in an oral biofilm. Consequently, it seems to be interesting and necessary to continue studying the EO antibacterial activity with CLSM techniques. The methodology should be directed to in situ antiseptic application, and the results obtained should be compared with other antiseptics. Thereby, a more reliable approach about the ability of EO as oral antiseptics could be obtained.
    Microbial pathogens and strategies for combating them: science, technology and education. Vol 2, Microbiology Book Series #4 edited by A. Méndez-Vilas, 12/2013: chapter In situ substantivity of the essential oils in the oral cavity: pages 1112-1122; Formatex Research Center., ISBN: 978-84-942134-0-3
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    Current microscopy contributions to advances in science and technology, Edited by A. Méndez-Vilas, 12/2012: chapter Applications in Biology and Medicine: pages 91-102; Formatex Research Center., ISBN: 978-84-939843-5-9


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