Exploiting optical coherence tomography to evaluate wear in spiral dental polishing systems.

This study aimed to evaluate the behavior of spiral polishing systems in restorative materials through optical coherence tomography (OCT). Performance of spiral polishers specific to resin and ceramics were evaluated. The surface roughness of restorative materials was measured, and images of the polishers were acquired by OCT and stereomicroscope. Surface roughness was reduced in ceramic and glass-ceramic composite polished with a system specific to resin (p<0.01). Surface area variation was observed on all polishers, except for the medium-grit polisher tested in ceramic (p<0.05). Similarity between images obtained through OCT and stereomicroscopy presented a Kappa inter- and intra-observer of 0.94 and 0.96, respectively. Then, OCT was able to evaluate wear areas in spiral polishers.

Activity of poly(methacrylic acid)-silver nanoparticles on fluconazole-resistant Candida albicans strains: Synergistic and cytotoxic effects.

AIMS: To synthesize and evaluate the antifungal activity of poly(methacrylic acid)-silver nanoparticles (PMAA-AgNPs) against nine Candida albicans isolated from clinical specimens. METHODS AND RESULTS: The effects of PMAA-AgNPs-fluconazole combination was analysed by checkerboard methodology. The synergistic potential of PMAA-AgNPs-fluconazole was determined by the fractional inhibitory concentration index (FICI). The inhibition of germ tube formation and the determination of PMAA-AgNPs cytotoxicity were also performed. All C. albicans strains were susceptible to PMAA-AgNPs and resistant to fluconazole. PMAA-AgNPs at subinhibitory concentrations restored the susceptibility of resistant C. albicans to fluconazole, whose FICI ranged from 0.3 to 0.5. The synergistic interaction of the combination was observed in eight of nine strains. The PMAA-AgNPs-fluconazole combination was also able to inhibit the germ tube formation. PMAA-AgNPs showed a dose-dependent decrease in viability for cells tested, with 50% cytotoxic concentration (CC50 ) values of 6.5, 4.9 and 6.8 µg ml-1 for macrophages, fibroblasts and Vero cells, respectively. CONCLUSIONS: This study demonstrated that, in general, PMAA-AgNPs acts synergistically in combination with fluconazole, inhibiting fluconazole-resistant C. albicans strains. PMAA-AgNPs-fluconazole combination was also able to inhibit germ tube formation, an important virulence factor. Inhibitory effect of PMAA-AgNPs alone or in combination was higher in C. albicans than in mammalian cells. SIGNIFICANCE AND IMPACT OF STUDY: This study shows the potential of PMAA-AgNPs combined with fluconazole to inhibit fluconazole-resistant C. albicans strains.