Metals and their alloys are materials that have long been used in stomatological prosthetics and orthodontics. The side effects of their application include reactions of the body such as allergies. Their source can be corrosion products as well as metal ions released in the corrosion process, which penetrate the surrounding tissue. In order to prevent the harming effect of metal alloys, intensive research has been performed to purify metal prosthetic restorations by way of modifying their surface. The study presents the investigation results of Ti(C, N)-type coatings applied to alloy Ni–Cr by means of the magnetronic method. Five coatings differing in the nitrogen and carbon content were investigated. The studies included the determination of the coatings’ chemical composition, construction, as well as the amount of ions released into the environment: distilled water, 0.9% NaCl and artificial saliva. The performed investigations showed that, in reference to an alloy without a coating, each coating constitutes a barrier reducing the amount of ions transferred into the examined solutions. So, Ti(C, N)-type coatings can be considered for biomedical applications as protective coatings of non-precious metal alloys.

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.

Fretting occurs during orthodontic treatment or wearing prosthesis. Although weight of particles is marginal, the total releasing area is more of a concern due to amount and volume of molecules. The aim of the study was to examine the fretting wear resistance of orthodontic and prosthetic alloy Ni-Cr-Mo samples coated with Ti(C, N) and to compare them with samples without any coating. Five groups of cylindrical shape samples (S1–S5) made of Ni-Cr-Mo were coated with Ti(C, N) layers with different content of C and N. The control group (S0) was without layer. The alloys underwent fretting wear resistance tests with amplitude 100 μm, at frequency 0.8 Hz with averaged unit load: 5, 10, and 15 N for 15 min. The samples were subjected to microscopic observations using scanning electron microscope and a laser scanning microscope. Samples with Ti(C, N) coatings revealed higher fretting wear resistance. The wear in each case with Ti(C, N) coatings was over twice as low. The lowest wear and thus the highest resistance was demonstrated by sample S3 (1.02 µm) whereas in control group-S0 (2.64 µm). The use of Ti(C, N)-type coatings reduces the adverse effects of fretting wear, decreasing the amount of ions released during orthodontic treatment or wearing prosthesis.

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.

Under natural physiological conditions, the oral cavity is colonized by a diverse range of microorganisms, which inhabit its anatomical structures as well as prosthetic restorations and the supragingival surfaces of implants. The metabolic activity of these microorganisms can contribute to microbiological corrosion, leading to the degradation of metal prosthetic materials. No material used for prosthetic elements is entirely resistant to bacterial adhesion. However, the application of protective coatings, such as Ti(C,N) coatings, on prosthetic surfaces can significantly reduce microorganism adherence. This study aimed to evaluate the influence of carbon and nitrogen content in Ti(C,N) coatings on reducing microorganism adhesion. Tests were conducted on five groups of Ni-Cr alloy specimens, each coated with Ti(C,N) layers containing varying amounts of carbon and nitrogen. The adhesion of E. coli bacteria and C. albicans fungi was assessed under both stationary and dynamic flow conditions. Results demonstrated that all tested coatings significantly reduced microorganism adhesion compared to uncoated Ni-Cr alloy samples.