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Localized surface plasmon resonance (LSPR) of gold nanoparticles has been reported to increase the antimicrobial effect of the photodynamic therapy. Although silver nanoparticles (AgNPs) are an efficient growth inhibitor of microorganisms, no studies exploring LSPR of AgNPs to enhance the photodynamic inactivation (PDI) have been related. In this work, we described the LSPR phenomenon of AgNP sand investigated its interaction with riboflavin, a natural photosensitizer. We evaluated the use of AgNPs coated with pectin (p-AgNP) in riboflavin (Rb)-mediated PDI of Escherichia coli (Gram- bacteria) and Streptococcus mutans (Gram + bacteria) using a blue light-emitting diode (λ = 455 ± 20 nm) of optical power 200 mW. Irradiance was 90 mW/cm 2 and radiant exposure varied according to the time exposure. Uptake of Rb and p-AgNP by the cells was evaluated by measuring the supernatant absorption spectra of the samples. We observed that LSPR of p-AgNPs was able to enhance the riboflavin photodynamic action on S. mutans but not on E. coli, probably due to the lower uptake of Rb by E. coli. Taken together, our results provide insights to explore the use of the LPRS promoted by silver nanostructures to optimize antimicrobial PDI protocols., (Copyright © 2018 Elsevier B.V. All rights reserved.)

There has been increasing interest on the development of clinically acceptable, more sensitive and specific methods for non-invasive diagnosis in Periodontics. In this pilot study, the performance of an Optical Coherence Tomography (OCT) system in imaging periodontal structures in humans was evaluated. Gingival sulcus depth measurements were obtained and compared with traditional probes. In total, 445 sites of 23 periodontally healthy individuals were measured by 3 instruments: North Carolina manual probe, Florida automated probe and OCT at 1325 nm. To obtain quantitative measurements from OCT images, the gingival refractive index was also determined. Discomfort/pain perception and the duration of examinations were compared among the instruments. The analysis of OCT images allowed the identification of relevant anatomic dental and periodontal regions. The average sulcus depth measured by OCT, 0.85 ± 0.27 mm and 0.87 ± 0.28 mm, was lower than the values obtained by manual and automated probing. Discomfort/pain were prevalent for traditional probes, which are invasive methods, than for the non-invasive OCT technique. OCT has the potential to be a reliable tool for in vivo periodontal tissues evaluation and for reproducible sulcus depth measurements in healthy sites. Further technological advances are required to reduce the procedure time and promote evaluation of posterior oral regions. Photonic assessment of periodontal tissue with OCT (top) in a clinical environment, showing tooth/gingiva features (bottom)., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)