Polytetrafluoroethylene added to acrylic resin: Surface properties and Candida albicans adherence

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Purpose To evaluate the surface properties and Candida albicans adherence on two acrylic resins, one polymerized by long cycle and the other by short polymerization cycle, with added 2% PTFE (wt/wt) (experimental groups) or not added (control groups) Methods The specimens were divided into four groups (n= 10 per group) (1) acrylic resin polymerized by long cycle, (2) acrylic resin polymerized by long cycle with added 2% PTFE, (3) acrylic resin polymerized by short cycle, and (4) acrylic resin polymerized by short cycle with added 2% PTFE After finishmg and polishing, all specimens were assessed for their surface roughness (mu m), contact angle (degrees) and surface free energy (erg/cm (2)) Saliva-coated specimens were submitted to the adherence assay with C albicans (ATCC 90028) Adhered cells were detached from the acrylic resin surface by ultrasonic waves at 7 watts for 30 seconds m phosphate buffered saline solution (PBS) This cell solution was serially diluted m PBS and plated on Sabouraud agar The results were expressed m colony forming units per surface area (CFU/mm(2)) The data was analyzed by two-way ANOVA The significance limit was set at 5% Results No statistical differences were found for roughness, contact angle and surface free energy There was a reduction trend in C albicans adherence in PTFE added to resins, but it was not statistically significant (Am J Dent 2010,23 201-204)234201204Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2006/03090 7

Effect of sucrose on the selection of mutans streptococci and lactobacilli in dental biofilm formed in situ

Microorganisms are selected in dental biofilm by the acidic environment created by sugar fermentation, but the effect of extracellular polysaccharide (EPS) on the counts of cariogenic bacteria is not clear. Dental biofilm was formed in situ for 13 days under exposure 8 times a day to distilled-deionized water, glucose + fructose or sucrose solutions. Mutans streptococci (MS) counts were not different among the groups, but lactobacilli (LB) were significantly higher in glucose + fructose and sucrose groups, without significant difference between them, irrespective of the higher insoluble EPS concentration in the sucrose biofilm matrix. The data suggest that exposure to sugar is more relevant for the predominance of LB in dental biofilm than for MS and that insoluble EPS does not change the counts of these microorganisms in the biofilm. Copyright (c) 2006 S. Karger AG, Basel40654654

EFFICACY OF DENTURE CLEANSERS ON CANDIDA SPP. BIOFILM FORMED ON POLYAMIDE AND POLYMETHYL METHACRYLATE RESINS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Statement of problem. Although new materials have emerged as options to fabricate removable dental prostheses, the development of Candida biofilms on these materials and the effectiveness of methods to control these pathogenic biofilms are poorly understood. Purpose. The purpose of this study was to evaluate the efficacy of denture cleansers on Candida single- and dual-species biofilms formed on polyamide resin. Material and methods. Polymethyl methacrylate (PMMA) resin (Acron MC) and polyamide resin (Flexite M.P.) specimens (n=116) were prepared, and their surface roughness was standardized (0.34 +/- 0.02 mu m). Surface free energy (SFE) was measured for some specimens (n=20 per resin), while the remainder were randomly divided by lottery into 24 groups (n=8) for biofilm assay. C. albicans and/or C. glabrata biofilm was formed for 72 hours, and then specimens were treated with an enzymatic cleanser solution (Polident 3 Minutes), a cleanser solution (Corega Tabs), or 0.5% sodium hypochlorite (NaOCl) solution. Water served as the negative control. Remaining adherent microorganisms were removed from the treated specimens by ultrasonic waves, and colony-forming units (CFU) of each microorganism were calculated. SEE data were analyzed by 1-way ANOVA, and Candida species data were analyzed by 3-way ANOVA followed by the Tukey-Kramer test (P=.05). Results. All tested biofilms displayed significantly higher growth on polyamide resin (P<.001), which presented the lowest SEE. Denture cleansers significantly decreased Candida levels; however, the 0.5% NaOCl solution was the only effective cleanser. C. glabrata revealed significantly higher CFU counts under all experimental conditions (P<.001). Conclusions. The highest Candida spp. biofilm growth was shown to occur on polyamide resin when compared with PMMA. Denture cleansers were able to remove Candida spp. biofilm formed on both denture base resins. (J Prosthet Dent 2010;105: 51-58)10515158Maranhao Research Foundation [FAPEMA-BM00042/08]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Maranhao Research Foundation [FAPEMA-BM00042/08

Production of a biofunctional titanium surface using plasma electrolytic oxidation and glow-discharge plasma for biomedical applications.

In this study, the authors tested the hypotheses that plasmaelectrolytic oxidation (PEO) and glow-discharge plasma (GDP) would improve the electrochemical, physical, chemical, and mechanical properties of commercially pure titanium (cpTi), and that blood proteinadsorption on plasma-treated surfaces would increase. Machined and sandblasted surfaces were used as controls. Standard electrochemical tests were conducted in artificial saliva (pHs of 3.0, 6.5, and 9.0) and simulated body fluid. Surfaces were characterized by scanning electron microscopy, energy-dispersive spectroscopy, x-ray photoelectron spectroscopy, atomic force microscopy, x-ray diffraction, profilometry, Vickers microhardness, and surface energy. For biological assay, the adsorption of blood serum proteins (i.e., albumin, fibrinogen, and fibronectin) was tested. Higher values of polarization resistance and lower values of capacitance were noted for the PEO and GDP groups (p < 0.05). Acidic artificial saliva reduced the corrosion resistance of cpTi (p < 0.05). PEO and GDP treatments improved the surface properties by enrichment of the surface chemistry with bioactive elements and increased surface energy. PEO produced a porous oxide layer (5-μm thickness), while GDP created a very thin oxide layer (0.76-μm thickness). For the PEO group, the authors noted rutile and anatase crystalline structures that may be responsible for the corrosion barrier improvement and increased microhardness values. Plasma treatments were able to enhance the surface properties and electrochemical stability of titanium, while increasing proteinadsorption levels