| 1. |
- Chávez de Paz, Luis Eduardo, et al.
(författare)
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The effects of antimicrobials on endodontic biofilm bacteria
- 2010
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Ingår i: Journal of Endodontics. - : Elsevier. - 0099-2399 .- 1878-3554. ; 36:1, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- Introduction In the present study, confocal microscopy, a miniflow cell system, and image analysis were combined to test in situ the effect of antimicrobials and alkali on biofilms of Enterococcus faecalis, Lactobacillus paracasei, Streptococcus anginosus, and Streptococcus gordonii isolated from root canals with persistent infections. Methods Biofilms formed for 24 hours were exposed for 5 minutes to alkali (pH = 12), chlorhexidine digluconate (2.5%), EDTA (50 mmol/L), and sodium hypochlorite (1%). The biofilms were then characterized by using fluorescent markers targeting cell membrane integrity (LIVE/DEAD) and metabolic activity (5-cyano-2,3-ditolyl tetrazolium chloride and fluorescein diacetate). In addition, the biofilm architecture and the extent to which coating of the substrate surface with collagen influenced the resistance pattern to the chemicals were also analyzed. Results NaOCl (1%) affected the membrane integrity of all organisms and removed most biofilm cells. Exposure to EDTA (50 mmol/L) affected the membrane integrity in all organisms but failed to remove more than a few cells in biofilms of E. faecalis, L. paracasei, and S. anginosus. Chlorhexidine (2.5%) had a mild effect on the membrane integrity of E. faecalis and removed only 50% of its biofilm cells The effects were substratum-dependent, and most organisms displayed increased resistance to the antimicrobials on collagen-coated surfaces. Conclusions The biofilm system developed here was sensitive and differences in cell membrane integrity and removal of biofilm cells after exposure to antimicrobials commonly used in endodontics was discernible.
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| 2. |
- Dorkhan, Marjan, et al.
(författare)
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Adherence of human oral keratinocytes and gingival fibroblasts to nano-structured titanium surfaces
- 2014
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Ingår i: BMC Oral Health. - : BioMed Central. - 1472-6831 .- 1472-6831. ; 14:75
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A key element for long-term success of dental implants is integration of the implant surface with the surrounding host tissues. Modification of titanium implant surfaces can enhance osteoblast activity but their effects on soft-tissue cells are unclear. Adherence of human keratinocytes and gingival fibroblasts to control commercially pure titanium (CpTi) and two surfaces prepared by anodic oxidation was therefore investigated. Since implant abutments are exposed to a bacteria-rich environment in vivo, the effect of oral bacteria on keratinocyte adhesion was also evaluated. METHODS: The surfaces were characterized using scanning electron microscopy (SEM). The number of adhered cells and binding strength, as well as vitality of fibroblasts and keratinocytes were evaluated using confocal scanning laser microscopy after staining with Live/Dead Baclight. To evaluate the effect of bacteria on adherence and vitality, keratinocytes were co-cultured with a four-species streptococcal consortium. RESULTS: SEM analysis showed the two anodically oxidized surfaces to be nano-structured with differing degrees of pore-density. Over 24 hours, both fibroblasts and keratinocytes adhered well to the nano-structured surfaces, although to a somewhat lesser degree than to CpTi (range 42-89% of the levels on CpTi). The strength of keratinocyte adhesion was greater than that of the fibroblasts but no differences in adhesion strength could be observed between the two nano-structured surfaces and the CpTi. The consortium of commensal streptococci markedly reduced keratinocyte adherence on all the surfaces as well as compromising membrane integrity of the adhered cells. CONCLUSION: Both the vitality and level of adherence of soft-tissue cells to the nano-structured surfaces was similar to that on CpTi. Co-culture with streptococci reduced the number of keratinocytes on all the surfaces to approximately the same level and caused cell damage, suggesting that commensal bacteria could affect adherence of soft-tissue cells to abutment surfaces in vivo.
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| 3. |
- Dorkhan, Marjan, et al.
(författare)
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Crystalline anatase-rich titanium can reduce adherence of oral streptococci
- 2014
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Ingår i: Biofouling (Print). - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 30:6, s. 751-759
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Tidskriftsartikel (refereegranskat)abstract
- Dental implant abutments that emerge through the mucosa are rapidly covered with a salivary protein pellicle to which bacteria bind, initiating biofilm formation. In this study, adherence of early colonizing streptococci, Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis and Streptococcus sanguinis to two saliva-coated anodically oxidized surfaces was compared with that on commercially pure titanium (CpTi). Near edge X-ray absorption (NEXAFS) showed crystalline anatase was more pronounced on the anodically oxidized surfaces than on the CpTi. As revealed by fluorescence microscopy, a four-species mixture, as well as individual bacterial species, exhibited lower adherence after 2 h to the saliva-coated, anatase-rich surfaces than to CpTi. Since wettability did not differ between the saliva-coated surfaces, differences in the concentration and/or configuration of salivary proteins on the anatase-rich surfaces may explain the reduced bacterial binding effect. Anatase-rich surfaces could thus contribute to reduced overall biofilm formation on dental implant abutments through diminished adherence of early colonizers.
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| 4. |
- Dorkhan, Marjan, et al.
(författare)
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Effects of saliva or serum coating on adherence of Streptococcus oralis strains to titanium
- 2012
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Ingår i: Microbiology. - : Society for General Microbiology. - 1350-0872 .- 1465-2080. ; 158:2, s. 390-397
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Tidskriftsartikel (refereegranskat)abstract
- The use of dental implants to treat tooth loss has increased rapidly over recent years. 'Smooth' implants showing high long-term success rates have successively been replaced by implants with rougher surfaces, designed to stimulate rapid osseointegration and promote tissue healing. If exposed in the oral cavity, rougher surfaces may promote bacterial adhesion leading to formation of microbial biofilms which can induce peri-implant inflammation. Streptococcus oralis is an early colonizer of oral surfaces and has been recovered from titanium surfaces in vivo. The purpose of this study was to examine the adherence of clinical strains of S. oralis to titanium with smooth or moderately rough surface topography and to determine the effect of a saliva- or serum-derived coating on this process. Adherence was studied using a flow-cell system with confocal laser scanning microscopy, while putative adhesins were analysed using proteomics of bacterial cell wall proteins. This showed that adherence to moderately rough was greater than to smooth surfaces. Serum did not promote binding of any studied S. oralis strains to titanium whereas a saliva-coating increased adherence in two of three strains tested. The high level of adherence to the moderately rough surfaces was maintained even in the presence of a saliva coating. The S. oralis strains that bound to saliva expressed an LPXTG-linked protein which was not present in the non-adherent strain. Thus strains of S. oralis differ in their capacity to bind to saliva-coated titanium and we propose that this is due to differential expression of a novel adhesin.
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| 5. |
- Dorkhan, Marjan, et al.
(författare)
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Salivary pellicles on titanium and their effect on metabolic activity in Streptococcus oralis
- 2013
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Ingår i: BMC Oral Health. - : BioMed Central. - 1472-6831 .- 1472-6831. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Titanium implants in the oral cavity are covered with a saliva-derived pellicle to which early colonizing microorganisms such as Streptococcus oralis can bind. The protein profiles of salivary pellicles on titanium have not been well characterized and the proteins of importance for binding are thus unknown. Biofilm bacteria exhibit different phenotypes from their planktonic counterparts and contact with salivary proteins may be one factor contributing to the induction of changes in physiology. We have characterized salivary pellicles from titanium surfaces and investigated how contact with uncoated and saliva-coated titanium surfaces affects metabolic activity in adherent cells of S. oralis. METHODS: Salivary pellicles on smooth titanium surfaces were desorbed and these, as well as purified human saliva, were subjected to two-dimensional gel electrophoresis and mass spectroscopy. A parallel plate flow-cell model was used to study binding of a fresh isolate of S. oralis to uncoated and saliva-coated titanium surfaces. Metabolic activity was assessed using the BacLight CTC Vitality Kit and confocal scanning laser microscopy. Experiments were carried out in triplicate and the results analyzed using Student's t-test or ANOVA. RESULTS: Secretory IgA, α-amylase and cystatins were identified as dominant proteins in the salivary pellicles. Selective adsorption of proteins was demonstrated by the enrichment of prolactin-inducible protein and absence of zinc-α₂-glycoprotein relative to saliva. Adherence of S. oralis to titanium led to an up-regulation of metabolic activity in the population after 2 hours. In the presence of a salivary pellicle, this effect was enhanced and sustained over the following 22 hour period. CONCLUSIONS: We have shown that adherence to smooth titanium surfaces under flow causes an up-regulation of metabolic activity in the early oral colonizer S. oralis, most likely as part of an adaptation to the biofilm mode of life. The effect was enhanced by a salivary pellicle containing sIgA, α-amylase, cystatins and prolactin-inducible protein which was, for the first time, identified as an abundant component of salivary pellicles on titanium. Further studies are needed to clarify the mechanisms underlying the effect of surface contact on metabolic activity as well as to identify the salivary proteins responsible for enhancing the effect.
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| 6. |
- Fröjd, Victoria, 1986, et al.
(författare)
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Effect of nanoporous TiO2 coating and anodized Ca2+ modification of titanium surfaces on early microbial biofilm formation.
- 2011
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Ingår i: BMC oral health. - London, UK : Springer Science and Business Media LLC. - 1472-6831. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- The soft tissue around dental implants forms a barrier between the oral environment and the peri-implant bone and a crucial factor for long-term success of therapy is development of a good abutment/soft-tissue seal. Sol-gel derived nanoporous TiO2 coatings have been shown to enhance soft-tissue attachment but their effect on adhesion and biofilm formation by oral bacteria is unknown.
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| 7. |
- Fröjd, Victoria, 1986, et al.
(författare)
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In situ analysis of multispecies biofilm formation on customized titanium surfaces
- 2011
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Ingår i: Molecular Oral Microbiology. - : John Wiley & Sons. - 2041-1006 .- 2041-1014. ; 26:4, s. 241-252
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Tidskriftsartikel (refereegranskat)abstract
- Many studies to identify surfaces that enhance the incorporation of dental implants into bone and soft-tissue have been undertaken previously. However, to succeed in the clinical situation, an implant surface must not support development of microbial biofilms with a pathogenic potential. As a first step in investigating this, we used two-species and three-species biofilm models with 16S ribosomal RNA fluorescence in situ hybridization and confocal laser scanning microscopy to examine the effect of surface characteristics on biofilm formation by species that can colonize titanium implants in vivo: Streptococcus sanguinis, Actinomyces naeslundii and Lactobacillus salivarius. Surfaces blasted with Al(2) O(3) (S(a) = 1.0-2.0 μm) showed a seven-fold higher bacterial adhesion after 2 h than turned surfaces (S(a) = 0.18 μm) whereas porous surfaces, generated by anodic oxidation (S(a) = 0.4 μm), showed four-fold greater adhesion than turned surfaces. Hence, increased roughness promoted adhesion, most likely through protection of bacteria from shear forces. Chemical modification of the blasted and oxidized surfaces by incorporation of Ca(2+) ions reduced adhesion compared with the corresponding non-modified surfaces. After 14 h, biofilm growth occurred in the three-species model but not in the two-species consortium (containing S. sanguinis and A. naeslundii only). The biofilm biovolume on all surfaces was similar, suggesting that the influence of surface characteristics on adhesion was compensated for by biofilm development.
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| 8. |
- Kindblom, Christian, et al.
(författare)
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Salivary proteins promote proteolytic activity in Streptococcus mitis biovar 2 and Streptococcus mutans
- 2012
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Ingår i: Molecular Oral Microbiology. - : John Wiley & Sons. - 2041-1006 .- 2041-1014. ; 27:5, s. 362-372
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Tidskriftsartikel (refereegranskat)abstract
- A major function of the salivary pellicle on oral surfaces is to promote colonization of the commensal microbiota by providing binding sites for adherence. Streptococcus mitis is an early colonizer of the oral cavity whereas Streptococcus mutans represents a later colonizer. To survive and grow, oral bacteria produce enzymes, proteases and glycosidases, which allow them to exploit salivary proteins as a nutrient source. In this study, adherence and proteolytic activity of S. mitis biovar 2 and S. mutans were investigated in a flow-cell model in the presence of different populations of surface-associated salivary proteins. Streptococcus mitis biovar 2 adhered well to surfaces coated with both a MUC5B-enriched fraction and a pool of low-density proteins containing MUC7, amylase, cystatin, gp340, immunoglobulin A, lactoferrin, lysozyme and statherin, whereas adherence of S. mutans to these proteins was poor. In environments of MUC5B or the low-density proteins, both S. mitis biovar 2 and S. mutans showed high levels of proteolytic activity. For S. mitis in the MUC5B environment, most of this activity may be attributable to contact with the molecules in the fluid phase although activity was also enhanced by adherence to surface-associated MUC5B. These data suggest that although they differ in their capacity to adhere to surface-associated salivary proteins, in the natural environment exploitation of saliva as a nutrient source can contribute to survival and colonization of the oral cavity by both S. mitis biovar 2 and S. mutans.
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| 9. |
- Neilands, Jessica, et al.
(författare)
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Fluoride-supplemented milk inhibits acid tolerance in root caries biofilms
- 2012
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Ingår i: Caries Research. - : S. Karger. - 0008-6568 .- 1421-976X. ; 46:2, s. 156-160
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigated the effect of fluoride on plaque acid tolerance. The test group consumed 200 ml of milk supplemented with 5 mg F/l as NaF once a day, the milk control group drank 200 ml of unsupplemented milk, and the no-milk control group did not consume milk in this manner. Plaque samples were taken at baseline and after 15 months. The proportion of acid-tolerant bacteria in plaque was estimated using LIVE/DEAD® BacLight™ staining after exposure to pH 3.5 for 2 h. The fluoride group showed a statistically significant decrease in plaque acid tolerance compared to baseline. This study shows that daily intake of fluoride in milk reduces plaque acid tolerance.
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| 10. |
- Nylander, Åsa, 1974-, et al.
(författare)
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Structural and functional analysis of the N-terminal domain of the Streptococcus gordonii adhesin Sgo0707
- 2013
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Ingår i: PLOS ONE. - : Public Library Science. - 1932-6203. ; 8:5, s. e63768-
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Tidskriftsartikel (refereegranskat)abstract
- The commensal Streptococcus gordonii expresses numerous surface adhesins with which it interacts with other microorganisms, host cells and salivary proteins to initiate dental plaque formation. However, this Gram-positive bacterium can also spread to non-oral sites such as the heart valves and cause infective endocarditis. One of its surface adhesins, Sgo0707, is a large protein composed of a non-repetitive N-terminal region followed by several C-terminal repeat domains and a cell wall sorting motif. Here we present the crystal structure of the Sgo0707 N-terminal domains, refined to 2.1 Å resolution. The model consists of two domains, N1 and N2. The largest domain, N1, comprises a putative binding cleft with a single cysteine located in its centre and exhibits an unexpected structural similarity to the variable domains of the streptococcal Antigen I/II adhesins. The N2-domain has an IgG-like fold commonly found among Gram-positive surface adhesins. Binding studies performed on S. gordonii wild-type and a Sgo0707 deficient mutant show that the Sgo0707 adhesin is involved in binding to type-1 collagen and to oral keratinocytes.
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