Biodeterioration of medical-grade silicone rubber used for voice prostheses: a SEM study.

Silicone voice prostheses used for rehabilitation of speech after total laryngectomy are inserted in an non-sterile habitat. Deposits on explanted Groningen Button voice prostheses revealed a biofilm, due to heavy colonization of the silicone surface by bacteria and yeasts. Furthermore, it was demonstrated by scanning electron microscopy on sectioned explants that the silicone material was deteriorated by filamentous and vegetative yeast cells.

A critical appraisal of positive cooperativity in oral streptococcal adhesion: Scatchard analyses of adhesion data versus analyses of the spatial arrangement of adhering bacteria.

Positive cooperativity is a mechanism proposed to account for the adhesion of bacteria to surfaces. In this paper, two methods that both claim to assess experimentally cooperative phenomena, viz. Scatchard analysis of adhesion data (using adhesion to vials) and analysis of the spatial arrangement of adhering cells (using a flow chamber), were compared and critically evaluated.

Flow chamber study of the adhesion of Prevotella intermedia to glass after preconditioning with mutans streptococcal species: kinetics and spatial arrangement.

The adhesion kinetics and spatial arrangement of a clinical isolate of Prevotella intermedia on bare glass and on glass which had been previously exposed to Streptococcus rattus or Streptococcus cricetus were studied using a parallel plate flow system and image analysis. When S. cricetus was the preconditioning organism the initial deposition rate and efficiency of P.

Adhesion of three Lactobacillus strains to human urinary and intestinal epithelial cells.

Three strains of urogenital lactobacilli were found to adhere in phosphate buffered saline to human uroepithelial cells in vitro according to thermodynamic principles, and to adhere in culture medium to intestinal cells with no such correlation. The most hydrophilic strain (water contact angle 54 degrees) L. casei RC-17 was the most adherent to uroepithelial (118 bacteria per cell) and intestinal cells (165 bacteria per cell).

Influence of pulsatile flow on the behaviour of human fibroblasts adhered to glass.

In the human body, cells contacting biomaterials surfaces are frequently exposed to pulsatile shear stresses, e.g. blood vessel prostheses.

Physico-chemical and structural properties of the surfaces of Peptostreptococcus micros and Streptococcus mitis as compared to those of mutans streptococci, Streptococcus sanguis and Streptococcus salivarius.

The surface properties of nine Streptococcus mitis and four Peptostreptococcus micros strains from the oral cavity were examined and compared with a large group of oral streptococci. Zeta potential and contact angle measurements were employed to determine physico-chemical cell surface properties. In addition, elemental surface concentration ratios were obtained via X-ray photoelectron spectroscopy, and surface structures were examined with transmission electron microscopy.

Heterogeneity of surfaces of subgingival bacteria as detected by zeta potential measurements.

Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans (A.a.) are Gram-negative bacteria which are implicated in various forms of periodontal disease.

Correlation between hydrophobicity and resistance to nonoxynol-9 and vancomycin for urogenital isolates of lactobacilli.

Seven clinical isolates of lactobacilli were found to be relatively hydrophobic with a mean water-contact angle of 66 +/- 15 degrees, and to be susceptible to 1% nonoxynol-9 and vancomycin. However, seven other strains were relatively hydrophilic with a mean water-contact angle of 32 +/- 13 degrees, and found to be resistant to 25% nonoxynol-9 and vancomycin. Thus, the surface properties of lactobacilli that influence susceptibility to antimicrobial agents may involve surface hydrophobicity.

Development and use of a parallel-plate flow chamber for studying cellular adhesion to solid surfaces.

A parallel-plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the behavior of human fibroblasts spread on glass is studied when exposed to an increasing laminar flow.

On the relative importance of specific and non-specific approaches to oral microbial adhesion.

In this paper, it is suggested that specificity and non-specificity in (oral) microbial adhesion are different expressions for the same phenomena. It is argued that the same basic, physicochemical forces are responsible for so-called 'non-specific' and 'specific' binding and that from a physico-chemical point of view the distinction between the two is an artificial one. Non-specific interactions arise from Van der Waals and electrostatic forces and hydrogen bonding, and originate from the entire cell.

Comparison of contact angles and adhesion to hexadecane of urogenital, dairy, and poultry lactobacilli: effect of serial culture passages.

The aim of this study was to examine the hydrophobicities of 23 urogenital, dairy, poultry, and American Type Culture Collection isolates of lactobacilli and to determine the effect on hydrophobicity of serially passaging the strains in liquid medium. To this end, strains were grown after isolation and identification and then serially passaged up to 20 times. Hydrophobicity was assessed through contact angle measurements on lawns of cells by using water, formamide, methylene iodide, 1-bromonaphthalene, and hexadecane as wetting agents and through measurement of their partitioning in a hexadecane-water system.

Bacterial growth inhibition and short-term clinical efficacy of a vegetable oil-based mouthrinse: preliminary study.

Bacterial growth of a vegetable oil-based product was determined in vitro. Growth of Streptococcus mutans and Veillonella alcalescens was strongly inhibited for dilutions up to 50x. On the basis of these results, it was decided to evaluate the short-term, clinical efficacy of a 1:10 dilution of the concentrated product in water.

Physicochemical and structural investigation of the surfaces of some anaerobic subgingival bacteria.

The surfaces of nine clinical isolates of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and Peptostreptococcus micros and that of laboratory strain P. gingivalis W83 were studied by using contact angle measurements, X-ray photoelectron spectroscopy, infrared spectroscopy, microelectrophoresis of whole cells, and transmission electron microscopy of whole and sectioned cells. P.

Influence of glutaraldehyde fixation of cells adherent to solid substrata on their detachment during exposure to shear stress.

In order to determine the response of fixed and nonfixed cells adherent to a solid substratum to shear stress, human fibroblasts were allowed to adhere and spread on either hydrophilic glass or hydrophobic Fluoroethylene-propylene (FEP-Teflon) and fixed with glutaraldehyde. Then, the cells were exposed to an incrementally loaded shear stress in a parallel plate flow chamber up to shear stresses of about 500 dynes/cm2, followed by exposure to a liquid-air interface passage. The cellular detachment was compared with the one of nonfixed cells.

Adhesion of mutants streptococci to glass with and without a salivary coating as studied in a parallel-plate flow chamber.

Deposition and adhesion to glass with and without a salivary coating in a parallel-plate flow chamber were studied with four strains of mutans streptococci. Stationary-state adhesion of the strains to uncoated glass ranged from 0.3 x 10(6) cm-2 (Streptococcus rattus HG218) to 12.

Sulcus temperature distributions in the absence and presence of oral hygiene.

In this study we investigated the possibility of using sulcus temperature measurements as an early indicator for the beginning of gingival inflammation. Sulcus temperature distributions over the arches appeared to obey a quadratic polynomial. With a test group of 10 volunteers, all dental students, small changes in temperature were measured after subjects refrained from all oral hygiene: A slight but significant tendency for the frontal temperature to increase after 14 days of no oral hygiene was, however, present.

Depth profiling of the elemental surface composition of the oral microorganism S. salivarius HB and fibrillar mutants by X-ray photoelectron spectroscopy.

X-ray photoelectron spectroscopy (XPS) on microbial cell surfaces requires freeze-drying of cells, and as a result, the cell surface appendages flatten out on the cell surface and form a collapsed fibrillar mass. At present, it is unclear how the density, length and composition of these fibrils influence the elemental surface composition as probed by XPS. The sampling depth of XPS can be varied by changing the electron take-off angle.

Characterization of eukaryotic cell surfaces prior to and after serum protein adsorption by X-ray photoelectron spectroscopy. Fibroblasts, HELA epithelial, and smooth muscle cells.

Elemental surface concentration ratios N/C,O/C, and P/C of fibroblasts, HELA epithelial cells, and smooth muscle cells, prior to and after washing in the absence or presence of serum proteins, were determined by X-ray photoelectron spectroscopy. Cell surfaces appeared to adsorb hardly any serum proteins, and the relatively high P/C, as compared to N/C and O/C, elemental surface concentration ratio indicated that the cell surfaces consisted mainly of the phospholipid bilayer, with little or no proteins present. The lack of adsorption of serum proteins to the cell surfaces seems at odds with the common notion that cells require adhesive proteins in order to adhere and spread.

Physicochemical characterization of Escherichia coli. A comparison with gram-positive bacteria.

Eight Escherichia coli strains were characterized by determining their adhesion to xylene, surface free energy, zeta potential, relative surface charge, and their chemical composition. The latter was done by applying X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). No relationship between the adhesion to xylene and the water contact angles of these strains was found.

Influence of substratum wettability on the strength of adhesion of human fibroblasts.

To determine the strength of adhesion and the detachment mechanisms of fibroblasts from substrata with different wettability, the behaviour of adhered cells was studied in a parallel-plate flow chamber during exposure to shear. Adhered cells were observed in situ, i.e.

A new profilometric method for determination of enamel and dentinal abrasion in vivo using computer comparisons: a pilot study.

A technique, sensitive enough to determine both dentinal and enamel abrasion in vivo, is presented. Computer-aided profilometry was used to measure the surface of dentinal and enamel samples before the experiment. Samples were subsequently placed in the buccal flanges of the mandibular dentures of two test subjects, who then brushed these pieces with a soft, multitufted brush, and two different toothpastes.

Cell-seeding of periodontal ligament fibroblasts. A novel technique to create new attachment. A pilot study.

This study was undertaken to test the hypothesis that seeded periodontal ligament cells are able to create new attachment. In one beagle dog, a premolar was removed and scrapings of the ligament were cultured. Artificial periodontal defects were made and the cultured ligament cells were seeded on the planed root surfaces and covered with muco-periosteal flaps.

Comparison of the physicochemical surface properties of Streptococcus rattus with those of other mutans streptococcal species.

Mutans streptococci comprise a group of seven closely related, yet distinct species. The distinction between the four species used in this study, namely Streptococcus sobrinus, Streptococcus cricetus, Streptococcus rattus, and Streptococcus mutans, has been made only recently on the basis of DNA homologies. In order to determine if there is a difference in the physicochemical surface properties of these species, strains were characterized by contact angles, zeta potentials and isoelectric points (IEP), elemental surface compositions by X-ray photoelectron spectroscopy, and molecular moieties by infrared spectroscopy.

Analogies in the two-dimensional spatial arrangement of adsorbed proteins and adhering bacteria: bovine serum albumin and Streptococcus sanguis 12.

Neither proteins nor bacteria adsorb or adhere homogeneously to a substratum surface. The final two-dimensional spatial arrangement depends on a complicated interplay between protein-protein (bacterium-bacterium) and protein (bacterium)-substratum interactions and the prevailing hydrodynamic conditions. In this paper, results are presented of two separate experiments in which bovine serum albumin (BSA) was adsorbed to, or Streptococcus sanguis 12 was deposited on substrata with different wettabilities in a search for analogies in the two-dimensional spatial arrangement of the absorbed proteins and adhering bacteria.