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Cornelio R.B.,University of Tromso | Wikant A.,University of Tromso | Mjosund H.,University of Tromso | Kopperud H.M.,Nordic Institute of Dental Materials | And 3 more authors.
Acta Odontologica Scandinavica | Year: 2014

Objective. The aim of this work was to assess the influence of the bis-EMA content on the degree of conversion (DC) and its effect on the water sorption and solubility. Materials and methods. In a polytetrafluorethylene (PTFE) mould, 30 samples (O = 5 mm, height = 2 mm) of four experimental dental composite resins were cured for 10 s, 20 s and 40 s. The DC was analysed by Fourier Transform (FT)-Raman spectroscopy. To analyse sorption and solubility, six samples (O = 15 mm and thickness = 1 mm) of each composite (n = 72) were stored in water at 37°C for different storage periods: 24 h, 7 days and 30 days. Results. When cured for 20 or 40 s the DC increased with the increasing content of bis-EMA. However, the presence of 15 wt% of bis-GMA did not affect the DC, except when cured with 10 s irradiation time. This study also found a correlation between the content of bis-EMA and the reduced values for sorption and solubility, for all storage times used, when the materials were cured with 20 s. Conclusions. The DC of mixtures with higher content of bis-EMA is affected by the presence of bis-GMA at lower energy density delivered from the curing device, suggesting that the restrictions caused by the presence of hydrogen bonds is dependent of the irradiation time used. © 2014 Informa Healthcare. Source

Price R.B.T.,Dalhousie University | Labrie D.,Dalhousie University | Bruzell E.M.,Nordic Institute of Dental Materials | Strassler H.E.,University of Maryland, Baltimore
Journal of Occupational and Environmental Hygiene | Year: 2016

Powerful blue-light emitting dental curing lights are used in dental offices to photocure resins in the mouth. In addition, many dental personnel use magnification loupes. This study measured the effect of magnification loupes on the “blue light hazard” when the light from a dental curing light was reflected off a human tooth. Loupes with 3.5x magnification (Design for Vision, Carl Zeiss, and Quality Aspirator) and 2.5x magnification (Design for Vision and Quality Aspirator) were placed at the entrance of an integrating sphere connected to a spectrometer (USB 4000, Ocean Optics). A model with human teeth was placed 40 cm away and in line with this sphere. The light guide tip of a broad-spectrum Sapphire Plus (Den-Mat) curing light was positioned at a 45° angle from the facial surface of the central incisor. The spectral radiant power reflected from the teeth was recorded five times with the loupes over the entrance into the sphere. The maximum permissible cumulative exposure times in an 8-hr day were calculated using guidelines set by the ACGIH. It was concluded that at a 40 cm distance, the maximum permissible cumulative daily exposure time to light reflected from the tooth was approximately 11 min without loupes. The weighted blue irradiance values were significantly different for each brand of loupe (Fisher's PLSD p < 0.05) and were up to eight times greater at the pupil than when loupes were not used. However, since the linear dimensions of the resulting images would be 2.5 to 3.5x larger on the retina, the image area was increased by the square of the magnification and the effective blue light hazard was reduced compared to without the loupes. Thus, although using magnification loupes increased the irradiance received at the pupil, the maximum cumulative daily exposure time to reflected light was increased up to 28 min. Further studies are required to determine the ocular hazards of a focused stare when using magnification loupes and the effects of other curing lights used in the dental office. © 2016 JOEH, LLC. Source

Mutluay M.M.,University of Oslo | Mutluay M.M.,Nordic Institute of Dental Materials | Oguz S.,Gazi University | Orstavik D.,University of Oslo | And 5 more authors.
Gerodontology | Year: 2010

Objectives: Microorganisms may colonise polysiloxane soft liners leading to bio-deterioration. The aim of this study was to investigate in vitro adhesion and in vivo biofilm formation of Candida species on polysiloxane surfaces. Methods: The materials used in this study were Molloplast B, GC Reline soft, Mollosil Plus, Silagum Comfort and Palapress Vario. The in vitro retention of clinical isolates of Candida albicans to the relining and denture-base materials by microscopic (scanning electron microscopy, SEM), conventional culturing methods and antimicrobial properties of these materials were studied. Candida found on materials and mucosa following long-term use were identified and quantified, and biofilms covering the surfaces were investigated by SEM. Results: There was a significant decrease in the number of cells attached in vitro to saliva-coated surfaces compared with non-treated surfaces. An oral Candida carriage of 78% was found. Candida albicans, C. glabrata, C. intermedia and C. tropicalis were identified. In vivo biofilm formation on the liners appeared as massive colonisation by microorganisms. Conclusions: The results of the in vitro experiments suggest that salivary film influences early colonisation of different C. albicans strains. The film layer also minimises the differences among different strains. The Candida carriage of these patients was similar to denture-wearing patients without soft liners. © 2009 The Gerodontology Society and John Wiley & Sons A/S. Source

Ahlfors E.E.,University of Oslo | Ahlfors E.E.,Nordic Institute of Dental Materials | Dahl J.E.,Nordic Institute of Dental Materials | Lyberg T.,University of Oslo
Archives of Oral Biology | Year: 2012

The effect of a single time exposure of SLS to the buccal mucosa of mice was compared to one application of the hapten OXA (oxazolone), evaluated by routine histology, immunohistochemistry and ELISA quantifications of cytokines. The SLS concentrations (2%, 4% and 8%) resulted in epithelial surface necrosis at 1-6 h, after 2-6 h accumulation of intra-epithelial neutrophils and at 24 h the main inflammatory cells were mononuclear. Increased concentrations of SLS gave more severe damage. CD4 + T cells were found at 6 h and increased slightly up to 24 h and were most frequently seen at the lowest SLS dose. The CD8 + T cells were kept at a low number during the whole 24 h observation period, but increased proportionally to the CD4 + T cells. One application of 1% OXA did not raise the number of cells of either phenotype (2-24 h). Neither IL-2 nor IFN-γ demonstrated increased levels during the week of observation at any concentration of SLS, contrary to one application of OXA which caused increased IL-2 levels both at the local application site and in the regional and distant lymph nodes. Regardless of SLS concentration, a minor increase in regional lymph node weight was observed 8-12 h after substance application, quickly to subside whilst one OXA application gave a maximal weight increase at 48-72 h. We conclude that oral mucosa irritant SLS reactions gave early surface necrosis and neutrophil infiltrations and later mononuclear cell infiltrations dominated by CD4 + T cells. The cytokines IL-2 and IFN-γ and lymphocyte proliferation in the regional lymph nodes was not observed after SLS application, contrary to hapten application. Source

Wikene K.O.,University of Oslo | Rukke H.V.,Nordic Institute of Dental Materials | Bruzell E.,Nordic Institute of Dental Materials | Tonnesen H.H.,University of Oslo
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2016

Natural deep eutectic solvents (NADES) are a newly discovered group of eutectics which has shown promise as a solvent in antimicrobial photodynamic therapy (aPDT). The purpose of this study was to investigate preparations of an anionic porphyrin, meso-tetra-(4-carboxyphenyl)-porphine (TCPP), solubilised in NADES, with regard to their physicochemical and antibacterial properties. The NADES CS (pH ∼ 0), ChX (pH ∼ 4) and MFG (pH ∼ 1) solubilised TCPP with absorption maximum ∼443 nm and emission maximum ∼678 nm, indicating formation of the TCPP dication. Dilution of TCPP-NADES > 1:1 (water) reduced the physical stability of the preparations. The photostability half-lives of TCPP in methanol, MFG, and CS were ∼9 h, 6.9 h and 3.2 h, respectively. Nanomolar concentrations of TCPP solubilised in diluted MFG combined with ≤27 J/cm2 blue light increased Gram-positive and Gram-negative bacterial phototoxicity, >99.98% and 96% bacterial reduction, respectively, compared to TCPP in PBS/ethanol under equivalent treatment conditions. TCPP solubilised in diluted CS was toxic to bacteria both in the absence (36-72% reduction) and presence of light. TCPP in CS, and in the CS component citric acid, induced a TCPP-concentration dependent increase in Gram-negative phototoxicity relative to controls, which was most pronounced for TCPP-CS. The mechanism behind the increased toxicity is unknown. © 2016 Elsevier B.V. All rights reserved. Source

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