Previous in vivo studies suggested that a high substratum surface free energy (s.f.e.) and an increased surface roughness facilitate the supragingival plaque accumulation. It is the aim of this clinical trial to explore the "relative" effect of a combination of these surface characteristics on plaque growth. 2 strips, one made of fluorethylenepropylene (FEP) and the other made of cellulose acetate (CA) (polymers with surface free energies of 20 and 58 erg/cm2, respectively) were stuck to the labial surface of the central incisors of 16 volunteers. Half the surface of each strip was smooth (Ra +/- 0.1 microns) and the other half was rough (Ra +/- 2.2 microns). The undisturbed plaque formation on these strips was followed over a period of 6 days. The plaque extension at day 3 and 6 was scored planimetrically from color slides. Finally, of 6 subjects samples were taken from the strips as well as from a neighbouring smooth tooth surface (s.f.e. 88 erg/cm2; Ra +/- 0.14 microns). These samples were analysed with a light microscope to score the proportion of coccoid cells, and small, medium, and large rods or fusiform bacteria. At day 3, a significant difference in plaque accumulation was only obtained when a rough surface was compared with a smooth surface. However, at day 6, significantly less plaque was recorded on FEP smooth (19.4%) when compared with CA smooth (39.5%). Between FEP rough (96.8%) and CA rough (98.2%), no significant difference appeared.(ABSTRACT TRUNCATED AT 250 WORDS)

An experimental technique is described to determine contact angles on bacterial layers deposited on cellulose triacetate filters. Measurements with water, water-n-propanol mixtures, and a-bromonaphthalene were employed to calculate surface free energies of various oral bacteria. Differences of 30 to 40 erg cm-2 were obtained for four different bacterial species isolated from the human oral cavity, if the concept of dispersion and polar surface free energies is applied. The free energies obtained were used to calculate interfacial free energies of adhesion of these bacteria from saliva onto tooth surfaces. Bacterial adhesion is energetically unfavorable, if the enamel surface free energy is less than 50 erg cm

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Glass surfaces were modified by end-grafting poly(ethylene oxide) (PEO) chains having molecular weights of 526, 2000, or 9800 Da. Characterization using water contact angles, ellipsometry, and X-ray photoelectron spectroscopy confirmed the presence of the PEO brushes on the surface with estimated lengths in water of 2.8-, 7.5-, and 23.7-nm, respectively. Adhesion of two bacterial (Staphylococcus epidermidis and Pseudomonas aeruginosa) and two yeast (Candida albicans and Candida tropicalis) strains to these brushes was studied and compared to their adhesion to bare glass. For the bacterium P. aeruginosa and the yeast C. tropicalis, adhesion to the 2.8-nm brush was comparable to their adhesion on bare glass, whereas adhesion to the 7.5- and 23.7-nm brushes was greatly reduced. For S. epidermidis, adhesion was only slightly higher to the 2.8-nm brush than that to the longer brushes. Adhesion of the yeast C. albicans to the PEO brushes was lower than that to glass, but no differences in adhesion were found between the three brush lengths. After passage of an air bubble, nearly all microorganisms adhering to a brush were removed, irrespective of brush length, whereas retention of the adhering organisms on glass was much higher. No significant differences were found in adhesion nor retention between experiments conducted at 20 and those conducted at 37 degrees C.

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Based on a literature review, a hypothesis is forwarded on the mechanism of initial bacterial adhesion to solid substrata, which accounts both for the role of specific microscopic surface components as well as for the role of non‐specific macroscopic surface properties (surface free energy, zeta potential or hydrophobicity). Three distinct regions in the adhesion process are suggested in which at large and intermediate separation distances adhesion is mediated by the macroscopic surface properties as surface free energy and surface charge, respectively. At small separation distances specific short‐range interactions can occur, leading to a strong and irreversible bonding, provided the water film present in between the interaction surfaces can be removed. A major role of hydrophobic groups, supposed to be associated with bacterial surface appendages is suggested to be its dehydrating capacity, enabling the removal of the vicinal water film yielding small areas of direct contact between protruberant parts of the cell surface and the substratum.

The purpose of this study was to examine the change in plaque area over nine days in vivo on four materials with different sinface freeenergies (s.f e.). Twelve healthy dental students participated in a crossover, split-mouth, double-blind study. Supragingivalplaqueformation was recorded over a nine-day period, on four different materials: fluorethylenepropylene (Teflon) (FEP), parafilm (PAR), cellulose acetate (CA), and enamel (E) with s.f. e. of 20, 26, 57, and 88 erg/cm2, respectively. Strips made from the first three materials were stack to the buccal surface of an upper incisor. The remaining incisor was carefully polished and served as an enamel surface. The increase in plaque was evaluated after three, six, and nine days. A planimetrical analysis was used so that the plaque area could be expressed as a percentage of the total buccal tooth surface. This procedure was repeated on each subject, so that at the end, each pair of central or lateral incisors received the four tested materials.The results indicated that the adherence of micro-organisms on pellicle-coated substrata was influenced by the material's s.f e.; there was an association between the s.fje. of the substrata and the supragingival plaque extension in vivo. High surface free-energy substrata in the oral cavity attracted more micro-organisms than did low energetic materials. Additionally, the bacterial adhesion seemed very weak on surfaces with a low s.f e. J Dent Res 68(5): 796-799, May, 1989 Introduction.

This paper describes the synthesis and characterization of polymer-peptide conjugates to be used as infection-resistant coating for biomaterial implants and devices. Antiadhesive polymer brushes composed of block copolymer Pluronic F-127 (PF127) were functionalized with antimicrobial peptides (AMP), able to kill bacteria on contact, and arginine-glycine-aspartate (RGD) peptides to promote the adhesion and spreading of host tissue cells. The antiadhesive and antibacterial properties of the coating were investigated with three bacterial strains: Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. The ability of the coating to support mammalian cell growth was determined using human fibroblast cells. Coatings composed of the appropriate ratio of the functional components: PF127, PF127 modified with AMP, and PF127 modified with RGD showed good antiadhesive and bactericidal properties without hampering tissue compatibility.