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BioMed Research International 2020The purpose of this study was to evaluate the effect of recycling on the properties of interface between 2 dental alloys and their corresponding porcelains.
PURPOSE
The purpose of this study was to evaluate the effect of recycling on the properties of interface between 2 dental alloys and their corresponding porcelains.
MATERIALS AND METHODS
Noble alloy (Pd-Cu-Ga) and high-noble alloy (Au-Pt) were used in this study. Metal matrices (cylinders 4 mm × 4 mm with pedestal 5 mm × 1 mm) were prepared by arc melting in argon after recasting 1-3 times. Corresponding porcelain with overall dimensions of 4 mm × 2 mm was veneered on each metal cylinder. There were 22 specimens in each alloy group. Specifically, two specimens of each group were chosen randomly for interfacial morphology and diffusion analyses by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The remaining 20 specimens were divided into 2 groups with or without thermal cycling. The bond strength was evaluated by shear test, and the data were analyzed by two-way analysis of variance (ANOVA). The failure mode of shear test specimen was observed with a stereoscopic microscopy and subjected to the exact probability test ( = 0.05).
RESULTS
According to the results from SEM, no obvious difference was observed in the interfacial morphology of both Pd-Cu-Ga and Au-Pt alloys among different recasting specimens. EDS analysis revealed that no significant difference was found in the width of elemental diffusion among 2 test alloys after recycling 1-3 times. Notably, in Pd-Cu-Ga alloy groups, the peak of Ga in thrice recasting was lower than those in first and second recastings. And there was no significant difference ( > 0.05) in the metal-ceramic shear bond strength of Pd-Cu-Ga and Au-Pt alloys after recycling 1-3 times, with or without thermal cycling. The results of failure modes observed on specimens were not affected by the recycling and thermal cycling in the 2 tested alloys.
CONCLUSIONS
Within the limitations of this study, the Pd-Cu-Ga and Au-Pt alloys can be recycled 2 times without significant changes on the properties of metal-ceramic interface, with or without thermal cycling.
Topics: Ceramics; Chromium Alloys; Dental Alloys; Dental Porcelain; Materials Testing; Metal Ceramic Alloys; Microscopy, Electron, Scanning; Recycling; Shear Strength; Surface Properties
PubMed: 32337242
DOI: 10.1155/2020/3529781 -
Toxicology and Applied Pharmacology Nov 2019The aim was to explore the biological effect of nickel (Ni) and titanium (Ti) ions released from dental alloys. NiTi alloy were exposed to 40 mL of artificial saliva...
The aim was to explore the biological effect of nickel (Ni) and titanium (Ti) ions released from dental alloys. NiTi alloy were exposed to 40 mL of artificial saliva (pH = 4.8, t = 37 °C). The dynamics of Ni and Ti ions release during corrosion were recorded on the 3th, 7th and 14th day. Biological effect of Ni and Ti ions released from alloy was explored on cell lines of human tongue CAL 27, liver Hep G2 and colon Caco-2. Neutral Red uptake assay for the estimation of cell viability/cytotoxicity and 2',7'-dichlorofluorescein diacetate fluorimetric assay for reactive oxygen species were used. Cells were exposed to the following concentration of corrosion products: 5.0×, 1.0×, 0.5 and 0.1× during the period of 24, 48 and 72 h. To check the effect of each metal separately, cells were exposed to nickel-chloride and titanium-dioxide of corresponding concentration. The release of Ni is higher than of Ti (15.1-30.4 μg/L for Ni and 9.0-17.3 μg/L for Ti, respectively) and 5× higher concentrations are needed to induce cytotoxic effect. Ni and Ti ions alone do not induce a major cytotoxic effect, but their combination does indicating their synergistic effect. Increase in concentration of Ni and Ti tends to increase cytotoxicity, Ti more than Ni. Cytotoxicity and induction of free radicals are in strong positive linear correlation. Ions released from NiTi alloy during 14 days do not induce significant cytotoxic effect and would not have a clinically important impact. Cytotoxic effect is largely the result of the induction of free radicals.
Topics: Caco-2 Cells; Cell Survival; Cytotoxins; Dental Alloys; Gastrointestinal Tract; Hep G2 Cells; Humans; Materials Testing; Nickel; Oxidative Stress; Saliva; Titanium
PubMed: 31628918
DOI: 10.1016/j.taap.2019.114784 -
Dental Materials : Official Publication... Apr 2021Previous studies have shown that the use of Cu electrodes compromises the electrochemical properties of Co-Cr and Ti alloys used for the fabrication of implant retained...
OBJECTIVES
Previous studies have shown that the use of Cu electrodes compromises the electrochemical properties of Co-Cr and Ti alloys used for the fabrication of implant retained superstructures by Electro Discharge Machining (EDM). A possible solution is the use of Ti instead of Cu electrodes and thus the aim of this study was to evaluate the effect of Cu and Ti electrodes on surface and electrochemical properties of two types of dental alloys used for fabrication of implant retained superstructures after EDM.
METHODS
Three full arch frameworks were prepared from a Co-Cr and three from Ti6Al7Nb alloy. One framework from each alloy was used as control, one was subjected to EDM with Cu electrodes and the last one with Ti electrodes. Morphological and elemental characterization was studied by SEM/EDX. The electrochemical properties of the alloys were evaluated by Open Circuit Potential (OCP) and Linear Sweep Voltammetry (LSV) in Ringer's solution. Electrochemical data were analyzed statistically by one way ANOVA and SNK multiple comparison tests at a = 0.05 RESULTS: All groups demonstrate the typical surface after EDM treatment with almost circular valleys and an increase in C and O content compared to control groups. Both alloys demonstrated an uptake of C and Cu by Cu electrodes and C and Ti after treatment with Ti electrodes. The use of Cu electrodes had a detrimental effect on corrosion resistance of Ti alloy.
SIGNIFICANCE
The use of Ti electrodes mitigates the degradation of electrochemical properties compared to Cu electrodes and from this standpoint is safer for the EDM of implant retained superstructures made of Co-Cr and Ti alloys.
Topics: Alloys; Corrosion; Dental Alloys; Electrodes; Humans; Materials Testing; Patient Discharge; Surface Properties; Titanium
PubMed: 33581911
DOI: 10.1016/j.dental.2021.01.012 -
The Journal of Prosthetic Dentistry Oct 2022Custom mini-implants are needed for edentulous patients with extensive mandibular deficiencies where endosteal placement is not possible. However, the best design for...
STATEMENT OF PROBLEM
Custom mini-implants are needed for edentulous patients with extensive mandibular deficiencies where endosteal placement is not possible. However, the best design for these mini-implants is unclear.
PURPOSE
The purpose of this in vitro study was to develop 2 dental mini-implant designs to support mandibular overdentures and evaluate the effect of their geometries on primary stability and stress distribution.
MATERIAL AND METHODS
Two mini-implant designs were developed with changes in the shape, size, and arrangement of threads and chamfers. The experimental mini-implants were made of Grade V titanium alloy (Ti-6Al-4V), (Ø2.0×10 mm) and submitted to a nanoscale surface treatment. Thirty mini-implants (n=10) were placed into fresh swine bones: experimental-threaded, experimental-helical, and a commercially available product model (Intra-Lock System) as the control. The biomechanical evaluations of the experimental mini-implants were compared with those of the control in terms of primary stability, through insertion torque (IT), and with the pullout test. The analysis of stress distribution was performed by using the method of 3D digital image correlation under 250-N axial load and 100-N oblique (30-degree angled model) load. The data were analyzed by ANOVA and the Tukey HSD test (α=.05).
RESULTS
The IT and pullout test presented a statistically significant difference for all mini-implants (P<.05), with higher IT for the experimental-threaded and maximum pullout force for the control, followed by threaded (P=.001) and helical (P=.001). Regarding the 3D digital image correlation, a lower incidence of stress was found in the cervical third for all mini-implants. No statistically significant differences were found between the designs evaluated (P>.05).
CONCLUSIONS
Comparing the experimental mini-implants with the commercially available control, the experimental-threaded model presented greater primary stability, and all mini-implants showed less stress in the cervical third.
Topics: Denture, Overlay; Dental Implants; Dental Alloys; Mandible; Titanium
PubMed: 33640085
DOI: 10.1016/j.prosdent.2020.06.043 -
Minerva Stomatologica Dec 2020Currently in dentistry, scientific research has been conducted in the study of dental implants. Being able to optimize dental implants, in all its mechanical and...
BACKGROUND
Currently in dentistry, scientific research has been conducted in the study of dental implants. Being able to optimize dental implants, in all its mechanical and biological components, is the main objective of the research. The purpose of this article was to evaluate the structure and the molecular features of dental implant titanium alloy.
METHODS
Two different internal hexagonal connection systems belonging to FDS76 have been used as sample. Beyond the literature search, fixture and abutment surface through an X-Ray Fluorescence (XRF) method have been analyzed.
RESULTS
The surfaces have achieved an excellent level of quality and low impurity, according to commercial pure titanium alloy.
CONCLUSIONS
This information will surely bring useful information to evaluate the quality of this type of alloy and possibly improve its features.
Topics: Alloys; Dental Abutments; Dental Alloys; Dental Implant-Abutment Design; Dental Implants; Dental Materials; Fluorescence; Materials Testing; Surface Properties; Titanium; X-Rays
PubMed: 33393276
DOI: 10.23736/S0026-4970.20.04358-7 -
International Endodontic Journal Apr 2023To compare design, metallurgy and mechanical performance of the ProTaper (PT) Ultimate system with instruments of similar dimensions from the ProGlider, PT Gold and PT...
AIM
To compare design, metallurgy and mechanical performance of the ProTaper (PT) Ultimate system with instruments of similar dimensions from the ProGlider, PT Gold and PT Universal systems.
METHODOLOGY
New PT Ultimate instruments (n = 248) were compared with instruments of similar dimensions from ProGlider (n = 31), PT Gold (n = 155) and PT Universal (n = 155) systems regarding their number of spirals, helical angle, blade symmetry, tip geometry, surface finishing, nickel/titanium ratio, phase transformation temperatures and mechanical performance. One-way anova and nonparametric Mood's median tests were used for statistical comparison (α = 5%).
RESULTS
All instruments had symmetrical blades without radial lands or flat sides, similar surface finishing and an almost equiatomic nickel/titanium ratio, whilst the number of spirals, helical angles and the tip geometry were different. PT Ultimate instruments showed 3 distinct heat treatments that matched with the colour of their metal wire. Slider and ProGlider instruments had similar R-phase start (Rs) and R-phase finish (Rf) temperatures. SX, F1, F2, F3 and Shaper instruments showed equivalent heat treatments (Rs ~45.6°C and Rf ~28.3°C) that were similar to their PT Gold counterparts (Rs ~47.9°C and Rf ~28.2°C), but completely distinct to the PT Universal ones (Rs ~16.2°C and Rf ~-18.2°C). Amongst the PT Ultimate instruments, the lowest maximum torques were observed in the SX (0.44 N cm), Slider (0.45 N cm) and Shaper (0.60 N cm) instruments, whilst the highest was noted in the FXL (4.90 N cm). PT Ultimate Slider and ProGlider had similar torsional (~0.40 N cm) and bending loads (~145.0 gf) (p = 1.000), whilst the other PT Ultimate instruments showed statistically significantly lower maximum torque, higher angle of rotation and lower bending load (higher flexibility) than their counterparts of the PT Universal and PT Gold systems.
CONCLUSIONS
The PT Ultimate system comprises instruments with 3 distinct heat treatments that showed similar phase transformation temperatures to their heat-treated analogues. PT Ultimate instruments presented lower torsional strength and superior flexibility than their counterparts, whilst maximum torque, angle of rotation and bending loads progressively increased with their sizes.
Topics: Titanium; Nickel; Hot Temperature; Equipment Failure; Materials Testing; Dental Alloys; Root Canal Preparation; Equipment Design; Torsion, Mechanical
PubMed: 36508297
DOI: 10.1111/iej.13880 -
Dental Materials Journal Aug 2023Adhesion of the most common dental biofilm bacteria to alloys used in orthodontics in relation to surface characteristics was analyzed. Streptococcus mutans (S. mutans),...
Adhesion of the most common dental biofilm bacteria to alloys used in orthodontics in relation to surface characteristics was analyzed. Streptococcus mutans (S. mutans), Streptococcus oralis (S. oralis), Veillonella parvula (V. parvula), and Aggregatibacter actinomycetemcomitans (A. actynomicetemcomitans) were incubated for 4 h with nickel-titanium (NiTi) and stainless-steel (SS) wires. The surface roughness and free energy of the alloys, as well as the hydrophobicity of the alloys and bacteria, were assessed. NiTi had higher surface free energy and rougher (p<0.001) and more hydrophilic surfaces than SS (p<0.001). The hydrophobic properties of the bacteria decreased in the following order: V. parvula>S. oralis>S. mutans>A. actynomicetemcomitans. Bacterial adhesion generally increased over time, though this pattern was influenced by the type of alloy and the bacteria present (p<0.001). In a multiple linear regression, the principal predictor of adhesion was bacterial hydrophobicity (p<0.001), followed by time (p<0.001); alloy surface characteristics had a low influence.
Topics: Dental Alloys; Orthodontic Wires; Surface Properties; Orthodontic Appliances; Alloys; Streptococcus mutans; Titanium; Stainless Steel
PubMed: 37271541
DOI: 10.4012/dmj.2022-235 -
Natural Product Research Apr 2024A phytochemical investigation of L.C.Xu ex X.W.Zheng afforded two novel polyacetylenes, tridecane-2-monoene-4,6,8-triyntylen-1,13-diol-12---glucoside () and...
A phytochemical investigation of L.C.Xu ex X.W.Zheng afforded two novel polyacetylenes, tridecane-2-monoene-4,6,8-triyntylen-1,13-diol-12---glucoside () and tetradecane-2,8-diene-4,6-diyne-1,14-diol-13---glucoside (), together with ten known compounds (). Their chemical structures were elucidated by NMR and MS spectrums as well as the comparison of the published data. Furthermore, the chemotaxonomy of the yielded compounds was also discussed.
Topics: Plant Extracts; Polyynes; Dental Porcelain; Glucosides; Glycosides; Molecular Structure; Titanium; Metal Ceramic Alloys
PubMed: 36255124
DOI: 10.1080/14786419.2022.2134864 -
Clinical Oral Investigations Sep 2023Ceramic-sintering affects bond strength and longevity of metal-ceramic. This study investigated the effect of sintering temperatures and times on metal-ceramic bond...
OBJECTIVES
Ceramic-sintering affects bond strength and longevity of metal-ceramic. This study investigated the effect of sintering temperatures and times on metal-ceramic bond strength vis-a-vis interfacial fracture toughness.
MATERIALS AND METHODS
One hundred eighty rectangular-shaped (25 × 8 × 1 mm) casting (Auriloy® (CA)) and CAD-milling (Ceramill Sintron® (MA)) alloys were prepared and randomly veneered with ceramic at normal (930 °C; (TN)), increased (940 °C; (TI)), and extremely increased (950 °C; (TE)) sintering temperatures and normal (1 min; (HN)), increased (2 min; (HI)), and extremely increased (3 min; (HE)) sintering time (n = 10/group). Pre-cracked was subjected to four loading-unloading cycles at 0.05 mm/min speed to determine interfacial fracture toughness from strain energy release rate (G). Microstructures were examined with a scanning electron microscope (SEM), energy-dispersive X-ray (EDX), and atomic force microscopy (AFM). ANOVA and Tukey comparisons were determined for significant differences (α = 0.05).
RESULTS
Significant differences in G due to the effect of alloy, sintering temperature, and time (p < 0.05) were indicated. MA revealed higher G than CA. Raising temperatures enabled increasing G for CA, not for MA. Extended sintering permitted increasing G for both alloys. Rougher surface of MA than CA was observed. Interfacial ion exchange was differently indicated between CA and MA.
CONCLUSIONS
Bond strength was influenced by alloy, sintering temperature, and time. Ceramic has better adhesion to MA than CA. Enhancing bond for CA was succeeded through increasing sintering temperature and time, whereas through extended sintering for MA.
CLINICAL RELEVANCE
MA offers stronger bond than CA. Enhancing bond is suggested by extended sintering. Raising temperature can enhance bond for CA, not for MA.
Topics: Dental Porcelain; Metal Ceramic Alloys; Dental Bonding; Surface Properties; Ceramics; Chromium Alloys; Materials Testing
PubMed: 37462729
DOI: 10.1007/s00784-023-05157-1 -
European Journal of Orthodontics Mar 2022The aim of this systematic review was to compare the different force delivery systems for orthodontic space closure by sliding mechanics. (Meta-Analysis)
Meta-Analysis
BACKGROUND/OBJECTIVES
The aim of this systematic review was to compare the different force delivery systems for orthodontic space closure by sliding mechanics.
SEARCH METHODS
Multiple sources including Cochrane Central, Ovid Medline, Embase etc. were used to identify all relevant studies.
SELECTION CRITERIA
Randomized controlled trials (RCT) of parallel-group and split-mouth designs were included.
PARTICIPANTS
Orthodontic patients of any age treated with fixed orthodontic appliances and requiring space closure.
DATA COLLECTION AND ANALYSIS
Search result screening, data extraction and quality assessment were performed independently and in duplicate by 2 reviewers. The included studies were grouped into parallel-arm and split-mouth studies and subgroup analysis was then performed for the type of retraction subsets; en-masse and individual canine retraction. A traditional meta-analysis, and network meta-analysis (NMA) for direct and indirect comparisons for the rate of space closure were performed.
RESULTS
Thirteen studies, six parallel-arm and seven split-mouth were included. The traditional meta-analysis comparing Nickel-titanium (NiTi) closed coil springs and elastomeric power chain for the rate of tooth movement showed statistically significant difference favouring NiTi springs (MD: 0.24; 95% CI, 0.03-0.45; I2 0%, P = 0.02) and the comparison between NiTi springs and active ligatures also showed statistically significant result favouring NiTi springs (MD: 0.53; 95% CI, 0.44-0.63; I2 0%, P ˂ 0.00001) for the rate of tooth movement. NMA for the rate of space closure showed fairly confident evidence for NiTi coil springs when compared with elastomeric chain and active ligatures. The NiTi coil spring ranked best between all methods of space closure.
CONCLUSIONS
There is moderate quality evidence in favour of NiTi coil springs for the rate of space closure when compared with active ligature and low quality of evidence favouring NiTi springs when compared with elastomeric chain. The ranking from NMA showed NiTi coil springs to be the best method for space closure with 99% chance. An urgent need for standardization of study designs and the need for development of an agreed core outcome sets and core outcome instrument measurement sets is evident.
REGISTRATION
PROSPERO CRD42020157811.
Topics: Dental Alloys; Elasticity; Humans; Orthodontic Space Closure; Orthodontic Wires; Titanium; Tooth Movement Techniques
PubMed: 34609513
DOI: 10.1093/ejo/cjab047