112 research outputs found
An active attachment biofilm model to develop anti-caries strategies
Full text linkThere is a need to develop new preventive agents that target the oral microflora. For this adequate testing models are required that allow for the screening of these agents. This thesis describes a number of experiments that were performed to develop, test and utilize a biofilm model suitable for this purpose. Overall the data showed that the new biofilm model allows for the screening of potential antimicrobial compounds. The sensitivity of the model was high enough to show dose response relations both in terms of colony-forming units (CFU) counts and metabolic activity with a selected anti-microbial. Moreover the model could show the effect of compounds added to the growth medium on important metabolic output parameters such as pH and ammonium production. Shifts in the bacterial composition of the polymicrobial biofilms could be monitored. Adding a propidium monoazide (PMA) treatment step enhanced the observed effects. The concept of adding a PMA treatment step when measuring shifts in the composition of polymicrobial samples was also tested on clinical samples. Apparently a prolonged exposure to oral rinses restricted the need for the PMA treatment to show changes in bacterial composition of buccal plaque and tongue samples, whereas it still proved to be necessary when analyzing changes in saliva
Evaluation of a fluoride-containing acidulated tablet, Xerodent©, in an in situ caries model
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Noninvasive dentistry: a dream or reality?
No full textVarious caries prevention and repair strategies are reviewed in this article ranging from the use of fluoride to nanohydroxyapatite particles. Several of the strategies which combine fluoride and calcium and phosphate treatments have both in vitro and in vivo data showing them to be efficacious if the surface integrity of the lesion is not breached. Once this has occurred, the rationale for cutting off the nutrient supplies to the pathogenic bacteria without the removal of the infected dentine, a noninvasive restorative technique, is discussed using existing clinical studies as examples. Finally two novel noninvasive restorative techniques using fluorohydroxyapatite crystals are described. The need for clinical data in support of emerging caries-preventive and restorative strategies is emphasized
Inhibition of enamel remineralization by lipoteichoic acid as determined in single sections.
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Factors associated with alkali production from arginine in dental biofilms
No full textAlkali production by oral bacteria in the oral cavity has been linked to protection against dental caries. The current study assessed various parameters associated with ammonium produced during arginine catabolism in dental biofilms. Polymicrobial biofilms were formed with saliva as the inoculum. The NH3 level and the pH of the spent medium were used to monitor and quantitate the bacterial reactions. The presence of sucrose, a low buffer capacity, and a low pH (≤ pH 4.5) were found to hamper alkali production from arginine. The rate of alkali production exhibited an optimum around pH 5.5. Biofilms were found to produce NH3 also from polypeptides and proteins in the medium. The biofilm age affected these processes. The experimental model proved valuable for the assessment of the collective bacterial reactions determining the overall pH outcome. This experimental approach could bridge the gap in our knowledge between pH-rise phenomena and caries susceptibility from clinical observations and studies performed on alkali-producing bacteria in well- controlled, though simplified, in vitro models. Analysis of our data supports the hypothesis that the initiation and progression of dental caries may be influenced by the relative rates of acid and base formation, which critically depend on the aforementioned parameters
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