In modern times, more and more different materials (including alloys) are in direct contact with human electrolytes (sweat, saliva, lymph, blood, etc.). One of the most important properties for the ...use of these materials is therefore their chemical inertness or resistance to corrosion when they are in contact with human electrolytes. Consequently, during the development of such new materials, it is necessary to study and understand their basic electrochemical behaviour in a given environment. The purpose of this research was to monitor the electrochemical behaviour of the new Au-Ge alloy in artificial sweat and artificial saliva solutions, depending on the electrolyte composition and exposure time. This new alloy represents a potential material for use in dentistry or for jewellery. The obtained results of the study show that the immersion time and the pH value have a significantly greater influence on the corrosion resistance of the new Au-Ge alloy than the composition of the electrolyte solution. The results of the SEM/EDX analysis additionally confirm the main results of the electrochemical measurements.
In this paper, we present the idea and development of a new gold-copper-zinc-germanium (AuCuZnGe) alloy, which is related to the method of production and research of its key properties, so that the ...new Au alloy could be used for jewelry production and in dental technology. The research design was associated with the determination of appropriate chemical composition, manufacturing technology, and performing the characterization. Melting and casting technologies were used to cast the AuCuZnGe alloy while rolling was used to prepare the cylinders and cutting to make square plates with a = 10 mm and thickness of 1 mm. Such plates were provided for corrosion testing. Observation of the plate′s microstructure was performed with Scanning Electron Microscopy (SEM) equipped by Energy-Dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD). Corrosion testing involved performing the following measurements: Polarization, the open circuit potentials, and linear polarization resistance. Based on the SEM, EDS, XRD, and results of corrosion testing it can be concluded that the new AuCuZnGe alloy possesses high corrosion stability and can be classified as a high noble alloy.
Implant-supported and implant-retained extraoral prostheses are reliable treatment options for patients with craniofacial defects. They provide stable retention and therefore enhance the patient's ...appearance and quality of life. Despite studies on survival rates of extraoral implants, little attention has been paid to the design of the implants used to support and retain extraoral prostheses.
The purpose of this longitudinal clinical study was to assess the long-term survival rate (1 to 12 years, mean 6 years) of 2 different designs of implants (disk: single, double, and triple and screw-type) used for extraoral epithesis anchorage.
Twenty-six participants with orbital and nasal defects, 10 of whom had had radiation treatment, were included in the study. Disk implants and extraoral (EO) screw implants were used and placed in the periorbital (15 participants) and perinasal regions (11 participants). Data were analyzed by using the Chi-square test and the Fisher Exact test for qualitative variables and the Mann-Whitney U test for comparison of quantitative variables. Implant survival rates were calculated by Kaplan-Meier analysis.
The overall 12-year survival rate of all implants was 90.3% (mean=79 months), with 92.9% for nasal (mean=84 months) and 88.2% for orbital (mean=75 months) implants. Related to the implant design, survival rates were as follows: for single-disk implants, 90.2%; for double disks, 94.6%; for triple disks, 88.3%; and for screw implants, 83.3%. In nonradiated participants, the implant survival rate was 97.6%, and for radiated participants, 76.1%.
Survival rates for implant-retained craniofacial prostheses are limited. The nasal site seems to be a more predictable implant site than the orbital site, with a higher overall survival rate. Also, implants inserted in radiated tissues have lower survival rates for both anatomic sites, with statistically significantly lower results in the orbital region. The most reliable type of implant among the disk implants used was the double disk in the orbital site and the single disk in the nasal site, which may indicate the advantages of some designs in specific areas.
Background/Aim. The cause of discolored gingiva (DG) is the presence of metal in the gingival tissue. DG is a relatively common case and is caused by the deposition of amalgam material in the ...gingival tissue during dental application or oral surgery. The aim of this study was to determine the significance of the presence of a cast post for the appearance of DG of abutment teeth (AT) in relation to the type of alloy used to make the fixed dental prosthesis (FDP). Methods. The study included 327 subjects with FDP. A total of 1,585 AT were examined. The subjects were classified into four groups depending on the type of alloy used to fabricate their FDPs (silver-palladium, gold, nickel-chromium alloy, or a combination of them). The presence of a cast post was con-firmed by X-ray or by inspection of the dental chart. The study was conducted over the course of one year. Results. DG was observed in more than one-third (37.7%) of the sub-jects, of which 57.3% had a cast post. In the case of AT, dis-coloration occurred in 14.6%. Cast post was present in 92.7% of AT with DG. Conclusion. DG occurred in all groups of subjects regardless of the type of alloy from which the FDP was fabricated. The presence of a cast post is of great significance for the appearance of gray-bluish discoloration of the gingiva.
Biocompatibility of copper-based shape memory alloy Lazic, Minja Milicic; Trišić, Dijana; Jakšić, Milica ...
International dental journal,
September 2021, 2021-09-00, 2021-09-01, Letnik:
71
Journal Article
Recenzirano
Odprti dostop
To represent biocompatibility of CuAlNi shape memory alloy manufactured by continuous casting.
Test samples were cut by electro erosion into discs shape. After polishing and cleaning, samples were UV ...sterilized for 1h. For the indirect test, discs were incubated in DMEM for 24h at 37°C in humidified 5% CO2 atmosphere (0.2 g/ml), and supernatant was collected the next day. Human gingival cells (HGCs) were isolated by outgrowth method from gingival tissues of healthy donors. HGCs were seeded in 96 well plates, and the next day undiluted material extract was added in corresponding wells. For the assessment of mitochondrial activity of HGCs after 24 and 168h from exposure to material supernatant, medium was discarded, and medium containing 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide was added to each well and incubated. After 4h supernatant was discarded, and dimethyl sulfoxide was added to each well and optical density was measured. Cells cultured in growth medium alone were used as control.
After 24h mitochondrial activity was increased in test group (HGCs exposed to material supernatant) in comparison to control group (untreated HGCs). After 168h of exposure to extracts mitochondrial activity was still higher in test group in comparison to control. T-test of paired samples showed that there was not statistically significant decrease in mitochondrial activity during time (p=0.642).
Although Cu-based alloys are controversial in terms of their biocompatibility, our study justified that biocompatibility depends on the manufacturing process and surface modification but not directly from the content of Cu.
Maxillofacial defects create physical, emotional and mental problems for the
patient. The task of surgical-prosthetic rehabilitation is to provide best
possible functional and esthetic solution. The ...aim of this paper was to
present a modern approach to auricular defect rehabilitation. A 24-year-old
patient with a lack of the right ear lobe due to trauma was admited for
aesthetic rehabilitation. Implant-retained ear prosthesis was indicated.
Three implants were placed into mastoid region of the temporal bone, and
after the period of osseointegration, an individualized bar was attached to
them for the retention of an auricular prosthesis made out of silicone.
Prosthetic rehabilitation, in this case, achieved excellent retention and
restored the appearance as well as self-confidence of the patient.
Background/Aim. Many studies investigated association between stress, anxiety or personality traits and sleep bruxism (SB), but results are still contradictory. We aimed to investigate whether there ...is a relation between clinically diagnosed sleep bruxism and salivary cortisol levels as one of the major stress biomarkers and to examine psychological factors and personality traits specific to sleep bruxism. Methods. A total of 23 sleep bruxism patients and 42 healthy non-sleep bruxism adults participated in this study. Diagnose of sleep-bruxism was assessed by selfreport and clinical examination and also confirmed by bedpartner. Morning saliva was collected from all participants for analyses of the cortisol level. Sleep bruxism patients underwent a psychodiagnostic personality interpretation using the Minnesota Multiphasic Personality Inventory ? MMPI-202 test. Results. Statistically significant difference between levels of morning salivary cortisol in the group of SB patients and the control group was recorded (t = 2.943, p < 0.01). Analysis of the personality profiles indicated that the sleep bruxism patients avoid contact with unpleasant feelings, especially depression, suppress the aggression and censor the expression of anger and rage. Conclusion. This study showed that patients with sleep bruxism have higher levels of salivary cortisol. Personality traits such as depression, hypomania and suppressed aggression were found to be common characteristics in patients with sleep bruxism. Present findings might support the hypothesis that sleep bruxism and psychological states such as stress may be related, but the cross-sectional nature of this study does not allow us to draw conclusions about the causal relationship between stress, personality traits and sleep bruxism.
nema
Introduction. The retention, stability, and plaque resistance of the obturator prosthesis significantly impact the improvement of the patient?s quality of life. The aim of this paper was to draw ...attention to the benefits of telescopic obturator prostheses made of polyether ether ketone (PEEK). Case report. We present an approach to the telescopic obturator fabrication using PEEK as the material of choice for the primary and secondary telescopic crowns, which are an integral part of the framework, in a 65-year-old patient with partial maxillectomy. The positioning of the teeth was made with a silicone key, and the featuring of the gingival part of the prosthesis was performed by a composite. Conclusion. PEEK is a polymer with good mechanical and chemical properties besides being bio-compatible. An obturator prosthesis made of this material does not incur enormous fabrication costs, and its satisfactory functionality contributes to the improvement of patients? lives.
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