Plaque-left-behind after brushing: intra-oral reservoir for antibacterial toothpaste ingredients.

OBJECTIVES: Plaque is never fully removed by brushing and may act as a reservoir for antibacterial ingredients, contributing to their substantive action. This study investigates the contribution of plaque-left-behind and saliva towards substantivity of three antibacterial toothpastes versus a control paste without antibacterial claims. MATERIALS AND METHODS: First, volunteers brushed 2 weeks with a control or antibacterial toothpaste. Next, plaque and saliva samples were collected 6 and 12 h after brushing and bacterial concentrations and viabilities were measured. The contributions of plaque and saliva towards substantivity were determined by combining control plaques with experimental plaque or saliva samples and subsequently assessing their viabilities. Bacterial compositions in the various plaque and saliva samples were compared using denaturing gradient gel electrophoresis. RESULTS: The viabilities of plaques after brushing with Colgate-Total® and Crest-Pro-Health® were smaller than of control plaques and up to 12 h after brushing with Crest-Pro-Health® plaques still contained effective, residual antibacterial activity against control plaques. No effective, residual antibacterial activity could be measured in saliva samples after brushing. There was no significant difference in bacterial composition of plaque or saliva after brushing with the different toothpastes. CONCLUSIONS: Plaque-left-behind after mechanical cleaning contributes to the substantive action of an antibacterial toothpaste containing stannous fluoride (Crest-Pro-Health®). CLINICAL RELEVANCE: The absorptive capacity of plaque-left-behind after brushing is of utmost clinical importance, since plaque is predominantly left behind in places where its removal and effective killing matter most. Therewith this study demonstrates a clear and new beneficial effect of the use of antibacterial toothpastes.

Acute and substantive action of antimicrobial toothpastes and mouthrinses on oral biofilm in vitro.

The aim of this study was to compare acute action by killing or disrupting oral biofilms through the use of antimicrobial toothpastes and mouthrinses in vitro and to investigate substantive action by absorption of antimicrobials in a biofilm. Biofilms from freshly collected human saliva were grown in 96-well microtitre plates. After removal of saliva, the wells of the microtitre plates were washed with sterile water (control), or exposed to a dilution series of mouthrinses (Corsodyl, Listerine, Meridol, Crest Pro Health) or to toothpaste slurries (Prodent Coolmint, Colgate Total, Zendium Classic, Crest Pro Health, Oral B Pro Expert, Crest Cavity Protection). Acute action was concluded from reduced continued (16 h) growth of treated biofilms with respect to the control. Substantive action was studied by exposing dead biofilms to mouthrinses or to toothpaste slurry. Substantive action through the absorption and subsequent release of antimicrobials from biofilm was concluded from reduced growth on top of the treated biofilms. All formulations showed acute action at the highest concentrations studied. Further dilution yielded loss of efficacy, or even stimulation of biofilm growth. Antimicrobial absorption in and the release of effective concentrations of antimicrobials from dead biofilms, was demonstrated for three selected antimicrobial products, indicating that antimicrobials remain bio-available for substantive action on new biofilms.

In vitro oral biofilm formation on triclosan-coated sutures in the absence and presence of additional antiplaque treatment.

PURPOSE: This study evaluated the in vitro plaque inhibitory effect of triclosan-coated polyglactin 910 sutures in the absence and presence of an additional antiplaque agent commonly used after oral surgery. MATERIALS AND METHODS: Triclosan-coated sutures were incubated for 4 hours in freshly collected human saliva and, when appropriate, subsequently treated with an antiplaque rinse containing chlorhexidine-cetyl pyridinium as active components. Sutures without a triclosan-coating served as a control. RESULTS: Triclosan-coated sutures harbored similar amounts of plaque as did uncoated sutures. Exposure to the antiplaque rinse caused significant decreases in viable organisms for uncoated and triclosan-coated sutures. However, after application of the antiplaque rinse, more micro-organisms were found on triclosan-coated than on uncoated sutures. CONCLUSION: Sutures coated with triclosan do not provide a sufficient antimicrobial effect to prevent in vitro colonization by oral bacteria, whereas use in combination with a chlorhexidine-cetyl pyridinium-containing antiplaque rinse appears to be counterproductive.

The influence of biosurfactants released by S. mitis BMS on the adhesion of pioneer strains and cariogenic bacteria.

The influence of Streptococcus mitis BMS biosurfactants on the adhesion of eight pioneer and four cariogenic oral bacterial strains was, for a first screening, examined in a microtiter plate assay. The adhesion to pellicle-coated wells of three cariogenic strains was inhibited >70% by the biosurfactants, while only one pioneer strain showed >70% reduction. The reduction for the other strains did not exceed 50%. Subsequently, adhesion of Streptococcus mutans ATCC 25175 and Streptococcus sobrinus HG 1025, both cariogenic strains, and Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, two pioneer strains, to biosurfactants-coated enamel with and without a salivary pellicle was studied in a parallel plate flow chamber. A biosurfactants coating to enamel with or without a pellicle caused a reduction in the number of adhering cariogenic organisms, although no such reduction was observed for the pioneer strains. Consequently, it is concluded that S. mitis BMS biosurfactants may play a protective role against adhesion of cariogenic bacteria.

Fourier transform infrared spectroscopy studies of alginate-PLL capsules with varying compositions.

Microencapsulation of cells is a promising approach to prevention of rejection in the absence of immunosuppression. Clinical application, however, is hampered by insufficient insight into the factors that influence the biocompatibility of the capsules. Capsules prepared of alginates with a high guluronic (G) acid content proved to be more adequate for clinical application since they are more stable, but, unfortunately, they are less biocompatible than capsules prepared of intermediate-G alginate. In order to get some insight into the physicochemical factors that influence the biocompatibility of capsules for the encapsulation of living cells, the chemical compositions of alginate[bond]Ca beads and alginate[bond]PLL capsules were studied by Fourier transform infrared spectroscopy. We found that during the transition of the alginate[bond]Ca beads to alginate[bond]PLL capsules, Ca connecting the alginate molecules, disappeared at the surface of both high-G and intermediate-G alginate[bond]PLL capsules. At the same time, it turned out that high-G alginate[bond]PLL capsules contained more hydrogen bonding than did intermediate[bond]G alginate capsules. Thus the well-known higher stability of high-G alginate[bond]PLL compared to intermediate-G alginate[bond]PLL capsules is not caused by a higher degree of binding to Ca of the alginate molecules but rather by the presence of more hydrogen bonds. Another observation was that after the transition from bead to capsule, high-G alginate[bond]PLL capsules contained 20% more PLL than the intermediate-G alginate[bond]PLL capsules. Finally, we show that in both high-G and intermediate-G alginate[bond]PLL capsules, the PLL exists in the alpha-helix, in the antiparallel beta-sheet, and in the random coil conformation. This study shows that FT-IR allows for successful analyses of the chemical factors essential for understanding differences in the biocompatibility of alginate[bond]PLL capsules.

Long-term biocompatibility, chemistry, and function of microencapsulated pancreatic islets.

Transplantation of encapsulated living cells is a promising approach for the treatment of a wide variety of diseases. Large-scale application of the technique, however, is hampered by insufficient biocompatibility of the capsules. In the present study, we have implemented new as well as previously reported technologies to test biocompatibility issues of immunoisolating microcapsules on the long term (i.e. 2 years) instead of usually reported short time periods. When transplanted empty, the capsules proved to be highly biocompatible not only for short periods (i.e. 1 month) but also on the long term as evidenced by the absence of any significant biological response up to 2 years after implantation in rats. The immunoprotective properties of the capsules were confirmed by prolonged survival of encapsulated islet allografts up to 200 days. The surface of the applied capsule was analyzed and provides new insight in the chemical structure of true biocompatible and immunoprotective capsules applicable for transplantation of encapsulated islets in type I diabetes.

Tissue responses against immunoisolating alginate-PLL capsules in the immediate posttransplant period.

Alginate-polylysine (PLL) capsules are commonly applied for immunoisolation of living cells for the treatment of a wide variety of diseases. Large-scale application of the technique, however, is hampered by insufficient biocompatibility of the capsules with failure of the grafts as a consequence. Most studies addressing biocompatibility issues of alginate-PLL capsules have focused on the degree of overgrowth on the capsules after graft failure and not on the reaction against the capsules in the immediate posttransplant period. Therefore, capsules were implanted in the peritoneal cavity of rats and retrieved 1, 5, and 7 days later for histological examination and X-ray photoelectron spectroscopy analysis for evaluation of chemical changes at the capsule surface. After implantation, the nitrogen signal increased from 5% on day 0, to 8.6% on day 7, illustrating protein adsorption on the capsule's surface. This increase in protein content of the membrane was accompanied by an increase in the percentage of overgrown capsules from 0.5 +/- 0.3% on day 1 to 3.3 +/- 1.6% on day 7. The cellular overgrowth was composed of monocytes/macrophages, granulocytes, fibroblasts, erythrocytes, multinucleated giant cells, and basophils. This overgrowth was not statical as generally assumed but rather dynamic as illustrated by our observation that at day 1 after implantation we mainly found monocytes/macrophages and granulocytes that on later time points were substituted by fibroblasts. As the inflammatory reaction predictably interfere with survival of encapsulated cells, efforts should be made to suppress activities or recruitment of inflammatory cells. These efforts may be temporary rather than permanent because most inflammatory cells have disappeared after 2 weeks of implantation.