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The Role of Nicotine, Cotinine and Caffeine on the Electrochemical Behavior and Bacterial Colonization to cpTi. An in vitro study.

Grant number: 11/20017-0
Support Opportunities:Scholarships in Brazil - Post-Doctoral
Effective date (Start): April 01, 2012
Effective date (End): March 31, 2013
Field of knowledge:Health Sciences - Dentistry - Dental Clinics
Principal Investigator:Wirley Goncalves Assuncao
Grantee:Valentim Adelino Ricardo Barão
Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil


The aim of this study is to investigate the role of different concentrations of nicotine, cotinine and caffeine on the corrosion behavior (electrochemical) of commercially-pure titanium (cpTi) and on the colonization of Streptococcus sanguinis on the surface of cpTi discs. The hypothesis to be tested is that the presence of nicotine, cotinine and caffeine would reduce the corrosion resistance of cpTi in artificial saliva and would increase the growing of microorganism on the surface of cpTi discs. It could explain why smokers present increased risk for dental implant loss. CpTi discs (15 mm diameter, 2 mm thickness) will be fabricated. In the electrochemical assay (n=5), standard tests such as open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic tests will be conducted in artificial saliva containing nicotine, cotinine and caffeine (0 - control; 0.3; 3; 30 and 300 µg/ml). The corrosion current density (Icorr), passivation current density (Ipass), corrosion potential (Ecorr), capacitance (Cdl) and polarization resistance (Rp) of the cpTi oxide layer will be determined. Discs' surfaces will be characterized by scanning electron microscope (SEM), atomic force microscope, and their surface roughness will be investigated. In the microbiological assay (n=3, with three independent tests), single biofilm of Streptococcus sanguinis will grow on cpTi discs during 7 days. Nicotine, cotinine and caffeine (0 - control; 0.3; 3; 30 and 300 µg/ml) will be added to the culture medium. The colony forming units will be determined (log CFU/cm2). The biofilm biomass will be measured with the crystal violet chromogenic assay, and the composition of the extracellular matrix (proteins and carbohydrates) will be investigated by the biocinchoninic acidic and colorimetric assays. SEM will be used to assess the adherence and structure of the biofilm on the cpTi discs. Quantitative data will be statistically analyzed at a significant level of 5%.

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BARAO, VALENTIM A. R.; RICOMINI-FILHO, ANTONIO P.; FAVERANI, LEONARDO P.; DEL BEL CURY, ALTAIR A.; SUKOTJO, CORTINO; MONTEIRO, DOUGLAS R.; YUAN, JUDY CHIA-CHUN; MATHEW, MATHEW T.; DO AMARAL, REGIANE C.; MESQUITA, MARCELO E.; et al. The role of nicotine, cotinine and caffeine on the electrochemical behavior and bacterial colonization to cp-Ti. Materials Science & Engineering C-Materials for Biological Applications, v. 56, p. 114-124, . (11/20021-7, 11/20017-0)

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