The microbial flora of the root canal dentin can cause failures in the conventional treatment of ... more The microbial flora of the root canal dentin can cause failures in the conventional treatment of infected root canals if it cannot be sufficiently removed by preparation and chemical disinfection of the root canal. The aim of this study is to examine the bactericidal effects of neody mium:y ttriumaluminum garnet (Nd:YAG) laser irradiation in the depth of the root canal dentin. Following sterilization, longitudinal section dentin slices of different thicknesses (100-1000 /um) were inoculated on one side with 4 /ul of a Streptococcus mutatis suspension. The opposite sides of the dentin slices were then irradiated four times for 10-20 sec (according to the sample area) using the Nd:YAG laser at a setting of 1.5 W, 15 pps with a 200 /urn glass fiber from an angle of about 5°. The bacteria were then removed from the dentin using vibration and plated out on culture dishes that were selective for Streptococcus mutatis. When compared with untreated control slices, counting of the colonies revealed a highly significant elimination of bacteria for all thicknesses following laser irradiation. Although the intensity of the laser irradiation decreased after penetration of a 1000pm dentin slice, the bactericidal mode of action was still effective. 69,491-501.
Early childhood caries (ECC) is closely related to high numbers of mutans streptococci, lactobaci... more Early childhood caries (ECC) is closely related to high numbers of mutans streptococci, lactobacilli and Candida albicans. Oral colonization of these microorganisms was monitored in a prospective clinical study in order to investigate the effect of comprehensive treatment under general anesthesia and the sustainability of microbial changes. Saliva samples were collected from 50 healthy infants with ECC before and in regular intervals up to 12 months after treatment. Microorganisms were detected by cultivation on selective agars (CRT® bacteria and Sabouraud/CandiSelect™) and scored. Additionally, plaque on upper front teeth and the dmft were recorded. Parents were repeatedly interviewed regarding the children's diet and oral hygiene, accompanied by corresponding advice. Plaque frequency and the numbers of mutans streptococci, lactobacilli and yeasts were significantly reduced as a result of treatment (p < 0.0001, Wilcoxon test). Nevertheless, this effect was not permanent. An ...
The proteolytic potential of the pathogenic fungus Candida albicans was evaluated by the identifi... more The proteolytic potential of the pathogenic fungus Candida albicans was evaluated by the identification and functional characterization of a peptidolytic enzyme isolated from the cell wall of the microorganism. Determination of basic structural and kinetic data identified a neutral arginine/alanine/leucine-specific metalloaminopeptidase of unknown function termed CaApe2, which is encoded by ORF CaO19.5197 (GenBank RefSeq XM_705313). Mass spectrometric tryptic peptide analysis and N-terminal protein sequencing revealed serine-88 to represent the N-terminus of CaApe2. Taking into account the results of DNA and protein sequence analysis including inspection of the genomic region upstream of ORF CaO19.5197, the gene CaAPE2 is likely to consist of two exons linked by a phase-2 intron with exons 1 and 2 encoding a signal peptide and the amino acids 88-954 of ORF CaO19.5197, respectively. The isolated CaApe2 protein shares an equally high similarity with the gene products ScAap1 and ScApe2, suggesting duplication of a phylogenetically ancient precursor gene in Saccharomyces cerevisiae. The observed failure to cleave human type-I and type-IV collagen in vitro challenges a direct role that secreted CaApe2 might play in the degradation of extracellular matrix components during host colonization, but does not exclude per se a contribution of the aminopeptidase to the pathogenicity of C. albicans.
was not generated by the yeast. This study provides experimental evidence that C. albicans is cap... more was not generated by the yeast. This study provides experimental evidence that C. albicans is capable of causing occlusal caries in rats at a high rate.
overall acid production by the yeast was below 10% at neutral conditions, in contrast to 42-66% a... more overall acid production by the yeast was below 10% at neutral conditions, in contrast to 42-66% at pH 4.0. Compared to lactobacilli, yeast required a concentration of glucose that was about 50 times higher to allow acid production at half the maximum speed. Considering the clinical data in the literature about the frequency and proportions of microorganisms present in early childhood caries lesions, the contribution of oral lactobacilli as well as C. albicans to overall microbial acid formation appears to be important.
The microbial flora of the root canal dentin can cause failures in the conventional treatment of ... more The microbial flora of the root canal dentin can cause failures in the conventional treatment of infected root canals if it cannot be sufficiently removed by preparation and chemical disinfection of the root canal. The aim of this study is to examine the bactericidal effects of neody mium:y ttriumaluminum garnet (Nd:YAG) laser irradiation in the depth of the root canal dentin. Following sterilization, longitudinal section dentin slices of different thicknesses (100-1000 /um) were inoculated on one side with 4 /ul of a Streptococcus mutatis suspension. The opposite sides of the dentin slices were then irradiated four times for 10-20 sec (according to the sample area) using the Nd:YAG laser at a setting of 1.5 W, 15 pps with a 200 /urn glass fiber from an angle of about 5°. The bacteria were then removed from the dentin using vibration and plated out on culture dishes that were selective for Streptococcus mutatis. When compared with untreated control slices, counting of the colonies revealed a highly significant elimination of bacteria for all thicknesses following laser irradiation. Although the intensity of the laser irradiation decreased after penetration of a 1000pm dentin slice, the bactericidal mode of action was still effective. 69,491-501.
Early childhood caries (ECC) is closely related to high numbers of mutans streptococci, lactobaci... more Early childhood caries (ECC) is closely related to high numbers of mutans streptococci, lactobacilli and Candida albicans. Oral colonization of these microorganisms was monitored in a prospective clinical study in order to investigate the effect of comprehensive treatment under general anesthesia and the sustainability of microbial changes. Saliva samples were collected from 50 healthy infants with ECC before and in regular intervals up to 12 months after treatment. Microorganisms were detected by cultivation on selective agars (CRT® bacteria and Sabouraud/CandiSelect™) and scored. Additionally, plaque on upper front teeth and the dmft were recorded. Parents were repeatedly interviewed regarding the children's diet and oral hygiene, accompanied by corresponding advice. Plaque frequency and the numbers of mutans streptococci, lactobacilli and yeasts were significantly reduced as a result of treatment (p < 0.0001, Wilcoxon test). Nevertheless, this effect was not permanent. An ...
The proteolytic potential of the pathogenic fungus Candida albicans was evaluated by the identifi... more The proteolytic potential of the pathogenic fungus Candida albicans was evaluated by the identification and functional characterization of a peptidolytic enzyme isolated from the cell wall of the microorganism. Determination of basic structural and kinetic data identified a neutral arginine/alanine/leucine-specific metalloaminopeptidase of unknown function termed CaApe2, which is encoded by ORF CaO19.5197 (GenBank RefSeq XM_705313). Mass spectrometric tryptic peptide analysis and N-terminal protein sequencing revealed serine-88 to represent the N-terminus of CaApe2. Taking into account the results of DNA and protein sequence analysis including inspection of the genomic region upstream of ORF CaO19.5197, the gene CaAPE2 is likely to consist of two exons linked by a phase-2 intron with exons 1 and 2 encoding a signal peptide and the amino acids 88-954 of ORF CaO19.5197, respectively. The isolated CaApe2 protein shares an equally high similarity with the gene products ScAap1 and ScApe2, suggesting duplication of a phylogenetically ancient precursor gene in Saccharomyces cerevisiae. The observed failure to cleave human type-I and type-IV collagen in vitro challenges a direct role that secreted CaApe2 might play in the degradation of extracellular matrix components during host colonization, but does not exclude per se a contribution of the aminopeptidase to the pathogenicity of C. albicans.
was not generated by the yeast. This study provides experimental evidence that C. albicans is cap... more was not generated by the yeast. This study provides experimental evidence that C. albicans is capable of causing occlusal caries in rats at a high rate.
overall acid production by the yeast was below 10% at neutral conditions, in contrast to 42-66% a... more overall acid production by the yeast was below 10% at neutral conditions, in contrast to 42-66% at pH 4.0. Compared to lactobacilli, yeast required a concentration of glucose that was about 50 times higher to allow acid production at half the maximum speed. Considering the clinical data in the literature about the frequency and proportions of microorganisms present in early childhood caries lesions, the contribution of oral lactobacilli as well as C. albicans to overall microbial acid formation appears to be important.
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