Corrosive Studies of a Prosthetic Ni-Cr Alloy Coated with Ti(C,N) Type Layers.

Background: Investigating the general corrosion resistance of Ti(C,N) type coatings on a prosthetic nickel alloy in the aspect of their use as protective coatings on prosthetic and orthodontic elements. Methods: Five groups of Ni-Cr alloy samples covered with Ti(C,N) type coatings differing in their carbon and nitrogen contents were used for the tests. The reference group included alloy samples without coatings. The samples were held for 105 days (2520 h) in salt spray chambers and examined by means of the NSS (neutral salt spray) and SWAAT (sea water acetic acid test) tests. After the periods of 14, 28, 81 and 105 days, the samples were removed and weighed, and their weight losses were determined. Results: In the case of each type of Ti(C,N) coating, the mass loss was lower than the mass loss of a sample without a coating, which makes it possible to state that coatings improve the corrosion resistance. No significant differences in the resistance were observed between the particular coatings. The corrosion rate of the examined coatings is close to parabolic. Conclusions: Ti(C,N) type coatings improve the resistance of a prosthetic Ni-Cr alloy and can be used as protective coatings for prosthetic and orthodontic elements.

Cytotoxicity of titanium carbonitride coatings for prostodontic alloys with different amounts of carbon and nitrogen.

The aim of our work was to examine the cytotoxicity of NiCr alloys coated with Ti(C,N) with different amounts of C and N in the layer on human gingival fibroblasts. Cells were cultured for 24 hours in the alloy extracts or on the surface of tested materials. The viability of the cells exposed to 1-, 3-, 5- and 7-day extracts did not change in comparison to the viability of cells cultured in a control medium assayed by an MTT test. Moreover, the flow cytometry analysis of fibroblasts cultured in direct contact with tested alloys revealed that all coatings except TiC did not induce apoptosis or necrosis. Interestingly, 24 hour fibroblast culture on alloys with Ti(C,N) coatings showed that the number of fibroblasts adhered to these alloys, evaluated by scanning electron microscope, increased with an increase in the content of nitrogen in the layer. The present study demonstrates that Ti(C,N) coatings were not cytotoxic and did not induce apoptosis in Ti(C,N) extracts, nor in direct contact with gingival fibroblasts, and can be considered for biomedical applications in the future.

Possibilities of applying Ti (C, N) coatings on prosthetic elements - research with the use of human endothelial cells.

PURPOSE: The aim of our study was to examine the effect of prosthetic alloys with Ti (C, N) coatings on viability and pro life ration of human cells employing an MTT assay with the use of human microvascular endothelial cells derived from the skin - HMEC-1 (Human Microvascular Endothelial Cells-1). METHODS: Cylindrical shape samples made of Ni-Cralloy were divided into S1-S5 groups and coated with Ti (C, N) layers with different content of C and N. S0 group - control group without layer. The alloys (S0-S5) were stored in an experimental medium (MCDB131 with antibiotics) for 30 days and then HMEC-1 cells were incubated in the alloy extract for 24 and 96 hours. Next, cell viability was determined using MTT method. RESULTS: In the case of samples incubated for both 24 and 96 hours there are statistically significant differences (with p-value <0.05) between the uncoated samples (S0 group) and all the other Ti (C, N) coated samples. Higher absorbance values were observed in all coated groups than in the control S0 group, where cell growth was statistically significantly lower. CONCLUSIONS: During incubation of endothelial cells with coated samples the number of cells was significantly bigger than the number with uncoated alloys. The best viability of cells was obtained from the S = 3 (with 51.94% at. Ti, 28.22% at. C and 19.84% at. N) group of samples. Ti (C, N) coatings may be applied as protective components on prosthetic elements made of base metal alloys.

The Sensitivity of Endodontic Enterococcus spp. Strains to Geranium Essential Oil.

Enterococci are able to survive endodontic procedures and contribute to the failure of endodontic therapy. Thus, it is essential to identify novel ways of eradicating them from infected root canals. One such approach may be the use of antimicrobials such as plant essential oils. Enterococcal strains were isolated from endodontically treated teeth by standard microbiological methods. Susceptibility to antibiotics was evaluated by the disc-diffusion method. The minimal inhibitory concentration (MIC) of geranium essential oil was investigated by microdilution in 96-well microplates in Mueller Hinton Broth II. Biofilm eradication concentrations were checked in dentin tests. Geranium essential oil inhibited enterococcal strains at concentrations ranging from 1.8-4.5 mg/mL. No correlation was shown between resistance to antibiotics and the MICs of the test antimicrobials. The MICs of the test oil were lower than those found to show cytotoxic effects on the HMEC-1 cell line. Geranium essential oil eradicated enterococcal biofilm at concentrations of 150 mg/mL. Geranium essential oil inhibits the growth of endodontic enterococcal species at lower concentrations than those required to reach IC50 against the HMEC-1 cell line, and is effective against bacteria protected in biofilm at higher concentrations. In addition, bacteria do not develop resistance to essential oils. Hence, geranium essential oil represents a possible alternative to other antimicrobials during endodontic procedures.