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European Endodontic Journal 2019Ever since their introduction, nickel-titanium (NiTi) alloys have continued to revolutionize the field of endodontics. They have considerable advantages over the... (Review)
Review
Ever since their introduction, nickel-titanium (NiTi) alloys have continued to revolutionize the field of endodontics. They have considerable advantages over the conventional stainless steel file in terms of mechanical properties. However, despite of their superior mechanical properties, NiTi alloys still pose some risk of fracture. Consequently, there has been considerable research conducted to investigate the mechanisms behind the occurrence of these procedural errors. Since the last decade, different proprietary processing procedures have been introduced to further improve the mechanical properties of NiTi alloys. These treatments include thermal, mechanical, electropolishing, and recently introduced electric discharge machining. The main purpose of these treatments is to impart a more martensitic phase into the files at normal body temperature, so that the maximum advantage of flexibility can be obtained. These heat-treated instruments also possess improved cyclic fatigue resistance when compared to conventional NiTi alloys. NiTi alloys can be subclassified as the instruments mainly containing austenitic phase (conventional NiTi, M-wire, R-phase), and those containing martensitic phase (controlled memory wire, ProTaper Gold, and Vortex Blue). Instruments based on austenitic alloys possess superelastic properties due to the stress-induced martensitic transformation. Contrary to this, martensitic alloys can easily be deformed due to phase transformation, and they can demonstrate the shape memory effect when heated. This review discusses the different phase transformations and heat treatments that the NiTi instruments undergo.
PubMed: 32161896
DOI: 10.14744/eej.2019.80664 -
The Cochrane Database of Systematic... Dec 2017Fixed prosthodontic treatment (crowns, fixed dental prostheses (FDPs), complete arch prostheses) involves the use of several different materials to replace missing tooth... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Fixed prosthodontic treatment (crowns, fixed dental prostheses (FDPs), complete arch prostheses) involves the use of several different materials to replace missing tooth structure. Traditionally full metal or metal frameworks veneered with ceramic (metal-ceramic (MC)) have been used. In recent years several different metal-free systems have become available to clinicians and patients. In general, metal-free restorations should allow practitioners to better reproduce natural tooth colour, avoiding shortcomings of MC restorations. The comparative in service clinical performance of fixed prosthodontic treatments of different materials is unclear.
OBJECTIVES
To assess the effects of metal-free materials for prosthodontic restorations compared to metal-ceramic or other conventional all-metal materials.
SEARCH METHODS
Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (searched 3 May 2017), Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 4) in the Cochrane Library (searched 3 May 2017), MEDLINE Ovid (1946 to 3 May 2017), and Embase Ovid (1980 to 3 May 2017). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials (searched 3 May 2017). No restrictions were placed on the language or date of publication when searching the electronic databases.
SELECTION CRITERIA
Randomised controlled trials (RCTs) in which the clinical performance of metal-free fixed prosthodontic restorations was compared with metal-ceramic (MC) or other conventional restorations in adult patients requiring prosthodontic treatment. RCTs in which the clinical performance of different kinds of metal-free systems were compared among themselves were also considered.
DATA COLLECTION AND ANALYSIS
We used standard methodological procedures expected by Cochrane. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted independently and in duplicate. Trial authors were contacted for missing information. Available results for the outcomes of interest of the systematic review of the studies included were tabulated as they could not be included in a formal meta-analysis.
MAIN RESULTS
Nine trials involving a total of 448 participants were included. We judged two trials to be at unclear risk of bias and seven to be at high risk of bias. The majority of items of risk of bias were evaluated to be at unclear or high risk level in more than 50% of the included trials. Each trial except two was addressing a different type of intervention. All evidence was rated as being of very low quality due to problems with risk of bias and imprecision of results, the latter being due to very small sample sizes, low event rates, 95% confidence intervals including the possibility of benefit for both the test and control groups, or combinations of these problems. This means that we are very uncertain about all of the results presented in this review.One trial compared metal-free single crowns (full contour zirconia) to cast gold single crowns in 224 participants and found insufficient evidence of a difference in failure rate after one year, but after five years there was some evidence of a benefit for the gold crowns. There was insufficient evidence of a difference for crown complications at either time of assessment.One trial compared three-unit metal-free FDPs (lithium disilicate) to three-unit metal-ceramic FDPs in 37 participants. There was insufficient evidence of a difference in bridge failure at one and six years, but some evidence of a benefit for the lithium disilicate group in terms of bridge complications at six years. One trial compared zirconia-ceramic FDPs to metal-ceramic FDPs in 34 participants but found insufficient evidence of a difference in bridge failures (i.e. no failures in either treatment group), bridge complications or patients' aesthetic evaluation at any time of assessment up to three years.One trial compared metal-free cantilevered FDPs to metal-ceramic cantilevered FDPs in 21 participants. There was insufficient evidence of a difference for any primary outcome: bridge failures (i.e. no failures in either treatment group), bridge complications, or patients' aesthetic evaluation at any time of assessment up to three years.One trial compared metal-free implant-supported screw retained single crowns (zirconia veneered with feldspathic ceramic) to metal-ceramic implant-supported screw-retained single crowns in 20 participants. There was insufficient evidence of a difference for any primary outcome: crown failures (i.e. no failures in either treatment group), crown complications, or satisfaction/aesthetic evaluation at any time of assessment up to two years.Two trials compared metal-free implant abutments (zirconia) to metal implant abutments both supporting single crowns in 50 participants. There was insufficient evidence of a difference in abutment failure at one year.One trial compared metal-free implant-supported FDPs made of two different types of zirconia ceramic in 18 participants. There was insufficient evidence of a difference in failures at any time of assessment up to 10 years (i.e. no failures in either treatment group). There was some evidence of a benefit for the zirconia-toughened alumina group in terms of complications (chipping).One trial compared metal-free tooth-supported FDPs made with two different veneering techniques (pressed versus layered) in 40 participants. There was insufficient evidence of a difference for failures (i.e. no failures in either treatment group) or complications at any time of assessment up to three years.
AUTHORS' CONCLUSIONS
There is insufficient evidence to support or refute the effectiveness of metal-free materials for fixed prosthodontic treatment over metal-ceramic or other type of standard restorations. The overall quality of existing evidence was very low, therefore great caution should be exercised when generalising the results of the included trials. Until more evidence becomes available clinicians should continue to base decisions on which material to use for fixed prosthodontic treatment on their own clinical experience, whilst taking into consideration the individual circumstances and preferences of their patients. There is urgent need of properly designed RCTs.
Topics: Crowns; Dental Alloys; Dental Materials; Dental Restoration, Permanent; Humans; Randomized Controlled Trials as Topic; Zirconium
PubMed: 29261853
DOI: 10.1002/14651858.CD009606.pub2 -
Case Reports in Dermatology 2022A 53-year-old lady underwent a left total knee arthroplasty. She developed a dermatitis over the left knee on postoperative day 5, which worsened over the next 2 weeks...
A 53-year-old lady underwent a left total knee arthroplasty. She developed a dermatitis over the left knee on postoperative day 5, which worsened over the next 2 weeks and spread to the trunk despite regular topical corticosteroids and oral antihistamines. Physical examination revealed an erythematous plaque over the left knee and urticated plaques over the neck. She was given a course of oral and topical corticosteroids with resolution. Subsequent patch testing showed a showing ++ reactions to gold and nickel, and + reactions to copper, palladium, rhodium, titanium, vanadium, zinc, and hydroquinone. Orthopedic implants contain metal alloys, which may include nickel, cobalt. Hypersensitivity to implants allergy may arise from the metal alloy or bone cement. Metal hypersensitivity reactions (MHR) can manifest as a local or systemic contact dermatitis weeks to months following exposure. The role of MHR in contributing to prosthesis failure is conflicting. In patients with no history of metal allergy, pre-implant patch testing is not routinely recommended as a positive patch test does not consistently predict in vivo metal-induced complication. MHR may be managed conservatively with good outcomes. However, in patients with MHR and implant failure, or in a preoperative patient with a proven and clinically relevant hypersensitivity, replacement of the implant, or implant with a titanium or oxidized zirconium alloy should be considered.
PubMed: 35496506
DOI: 10.1159/000523740 -
Asian Journal of Andrology 2020Since their popularization, genitourinary prosthetics have remained a gold-standard therapy for the treatment of erectile dysfunction and stress urinary incontinence and... (Review)
Review
Since their popularization, genitourinary prosthetics have remained a gold-standard therapy for the treatment of erectile dysfunction and stress urinary incontinence and in cases of testicular loss or dysfunction. They have also represented an area of significant innovation, which has contributed to excellent long-term outcomes. Given this history, the objective of the current review was to provide a 5-10-year outlook on anticipated trends and developments in the field of genitourinary prosthetics. To accomplish this objective, a PubMed and patent search was performed of topics relating to penile and testicular prostheses and urinary sphincters. In regard to penile prostheses, findings demonstrated several new concepts including temperature-sensitive alloys, automated pumps, devices designed specifically for neophalluses, and improved malleable designs. With artificial urinary sphincters, new concepts include the ability to add or remove fluid from an existing system, two-piece systems, and new mechanisms to occlude the urethra. For testicular prosthetics, future implementations may not only better replicate the feel of a biological testicle but also add endocrinological functions. Beyond device innovation, the future of prosthetics is also one of expanding geographic boundaries, which necessitates variable cost modeling and regulatory considerations. Surgical trends are also changing, with a greater emphasis on nonnarcotic, postoperative pain control, outpatient surgeries, and adjunctive techniques to lengthen the penis and address concomitant stress incontinence, among others. Concomitant with device and surgical changes, future considerations also include a greater need for education and training, particularly given the rapid expansion of sexual medicine into developing nations.
Topics: Erectile Dysfunction; Humans; Male; Penile Implantation; Penile Prosthesis; Prostheses and Implants; Prosthesis Design; Prosthesis Implantation; Testicular Diseases; Urinary Incontinence, Stress; Urinary Sphincter, Artificial; Urologic Surgical Procedures, Male
PubMed: 31571642
DOI: 10.4103/aja.aja_103_19 -
ACS Pharmacology & Translational Science Feb 2023Nanomaterials have now found applications across all segments of society including but not limited to energy, environment, defense, agriculture, purification, food... (Review)
Review
Nanomaterials have now found applications across all segments of society including but not limited to energy, environment, defense, agriculture, purification, food medicine, diagnostics, and others. The pandemic and the vulnerability of humankind to emerging viruses and other infectious diseases has renewed interest in nanoparticles as a potential new class of antivirals. In fact, a growing body of evidence in the literature suggests nanoparticles may have activity against multiple viruses including HIV, HNV, SARS-CoV-2, HBV, HCV, HSV, RSV, and others. The most described antiviral nanoparticles include copper, alloys, and oxides including zinc oxide (ZnO), titanium oxide, iron oxide, and their composites, nitrides, and other ceramic nanoparticles, as well as gold and silver nanoparticles, and sulfated and nonsulfated polysaccharides and other sulfated polymers including galactan, cellulose, polyethylenimine, chitosan/chitin, and others. Nanoparticles, synthesized via the biological or green method, also have great importance and are under major consideration these days, as their method of synthesis is easy, reliable, cost-effective, efficient, and eco-friendly, and is done using easily available sources such as bacteria, actinomycetes, yeast, fungi, algae, herbs, and plants, in comparison to chemically mediated synthesis. Chemical synthesis is highly expensive and involves toxic solvents, high pressure, energy, and high temperature conversion. Examples of biologically synthesized NPs include iron oxide, Cu and CuO NPs, and platinum and palladium NPs. In contrast to traditional medications, nanomedications have multiple advantages: their small size, increased surface to volume ratio, improved pharmacokinetics, improved biodistribution, and targeted delivery. In terms of antiviral activity, nanoscale interactions represent a unique mode of action. As reviewed here their biomedical application as an antiviral has shown four major mechanisms: (1) direct viral interaction prohibiting the virus from infecting the cell, (2) interaction to receptor or cell surface preventing the virus from entering the host cells, (3) preventing the replication of the virus, or (4) other processing mechanisms which inhibit the spread of virus. Here these pharmacologic mechanisms are reviewed and the challenges for technology translation are discussed in more detail.
PubMed: 36798473
DOI: 10.1021/acsptsci.2c00195 -
Nanomaterials (Basel, Switzerland) Nov 2023Nanomedicine relies on the exploitation of nanoscale constructs for therapeutic and diagnostic functions. Gold and gold-iron alloy nanoparticles (NPs) are two examples...
Nanomedicine relies on the exploitation of nanoscale constructs for therapeutic and diagnostic functions. Gold and gold-iron alloy nanoparticles (NPs) are two examples of nanomaterials with favorable features for use in nanomedicine. While gold NPs have been studied extensively in the last decades, they are not biodegradable. Nonetheless, biodegradation was recently observed in gold alloys with iron obtained using laser ablation in liquid (LAL). Hence, there is a significant interest in the study of the biological effects of gold and gold-iron alloy nanoparticles, starting from their tolerability and cytotoxicity. In this study, these two classes of NPs, obtained via LAL and coated with biocompatible polymers such as polyethylene glycol, were investigated in terms of their cytotoxicity in fibroblasts, prostate cancer cells (PC3) and embryonic kidney cells (HEK). We also explored the effects of different synthetic procedures, stabilizing additives, and the possible mechanisms behind cell mortality such as the formation of reactive oxygen species (ROS) or ferroptosis. NPs larger than 200 nm were associated with lower cell tolerability. The most tolerable formulations were pure PEG-Au NPs, followed by PEG-Au-Fe NPs with a hydrodynamic size < 50 nm, which displayed a toxicity of only 20% in fibroblasts after 72 h of incubation. In addition, tumor cells and highly proliferating HEK cells are more sensitive to the NPs than fibroblasts. However, a protective effect of catalase was found for cells incubated with PEG-Au-Fe NPs, indicating an important role of hydrogen peroxide in alloy NP interactions with cells. These results are crucial for directing future synthetic efforts for the realization of biocompatible Au NPs and biodegradable and cytocompatible Au-Fe alloy NPs. Moreover, the correlation of the cytocompatibility of NPs with ROS and ferroptosis in cells is of general interest and applicability to other types of nanomaterials.
PubMed: 38063740
DOI: 10.3390/nano13233044 -
Bioactive Materials Dec 2019Metallic implant materials possess adequate mechanical properties such as strength, elastic modulus, and ductility for long term support and stability . Traditional... (Review)
Review
Metallic implant materials possess adequate mechanical properties such as strength, elastic modulus, and ductility for long term support and stability . Traditional metallic biomaterials, including stainless steels, cobalt-chromium alloys, and titanium and its alloys, have been the gold standards for load-bearing implant materials in hard tissue applications in the past decades. Biodegradable metals including iron, magnesium, and zinc have also emerged as novel biodegradable implant materials with different degradation rates. However, they do not possess good bioactivity and other biological functions. Bioactive glasses have been widely used as coating materials on the metallic implants to improve their integration with the host tissue and overall biological performances. The present review provides a detailed overview of the benefits and issues of metal alloys when used as biomedical implants and how they are improved by bioactive glass-based coatings for biomedical applications.
PubMed: 31667443
DOI: 10.1016/j.bioactmat.2019.09.002 -
Materials (Basel, Switzerland) Jan 2019Metallic biomaterials are used in medical devices in humans more than any other family of materials. The corrosion resistance of an implant material affects its... (Review)
Review
Metallic biomaterials are used in medical devices in humans more than any other family of materials. The corrosion resistance of an implant material affects its functionality and durability and is a prime factor governing biocompatibility. The fundamental paradigm of metallic biomaterials, except biodegradable metals, has been "the more corrosion resistant, the more biocompatible." The body environment is harsh and raises several challenges with respect to corrosion control. In this invited review paper, the body environment is analysed in detail and the possible effects of the corrosion of different biomaterials on biocompatibility are discussed. Then, the kinetics of corrosion, passivity, its breakdown and regeneration in vivo are conferred. Next, the mostly used metallic biomaterials and their corrosion performance are reviewed. These biomaterials include stainless steels, cobalt-chromium alloys, titanium and its alloys, Nitinol shape memory alloy, dental amalgams, gold, metallic glasses and biodegradable metals. Then, the principles of implant failure, retrieval and failure analysis are highlighted, followed by description of the most common corrosion processes in vivo. Finally, approaches to control the corrosion of metallic biomaterials are highlighted.
PubMed: 30696087
DOI: 10.3390/ma12030407 -
International Journal of Molecular... Nov 2022This work deals with a physical and chemical surface characterization of quaternary 18K, 14K, and 9K gold alloys and pure polycrystalline gold substrates. Surface...
This work deals with a physical and chemical surface characterization of quaternary 18K, 14K, and 9K gold alloys and pure polycrystalline gold substrates. Surface microstructure and composition are evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence spectroscopy. Corrosion resistance of 18K gold alloys is explored by potentiodynamic polarization showing the influence of the manufacturing process on materials fabricated as plates and wires. The research is also in the framework of one of the most common strategies on the modification of metallic surface properties, i.e., the building of self-assembled monolayers (SAM) from organic thiols. The metal affinity of the head group to produce the coating of the substrate by covalent binding is approached by using thiol compounds with different molecular structures and functional group chemistries exposed to an electrolyte solution. Therefore, a comparative study on the surface protection of a quaternary 18K gold alloy and pure gold substrates by SAMs of 6-mercaptopurine (6MP), 1-decanethiol (DT), and 11-mercaptoundecanoic acid (MUA) has been carried out. Surface modification and SAM organization are followed by cyclic voltammetry (CV), and the behavior of the double layer of the electrode-electrolyte interface is evaluated by electrochemical impedance spectroscopy (EIS). The study of these materials allows us to extract fundamental knowledge for its potential application in improving the bioactive properties of different jewelry pieces based on 18K gold alloys.
Topics: Gold Alloys; Sulfhydryl Compounds; Corrosion; Gold; Surface Properties
PubMed: 36430610
DOI: 10.3390/ijms232214132 -
Journal of Oral Science Jul 2022Recently in Japan, due to the increased prices of palladium and gold, cast titanium restorations have been included in the Japanese national health insurance system. The... (Review)
Review
Recently in Japan, due to the increased prices of palladium and gold, cast titanium restorations have been included in the Japanese national health insurance system. The purpose of this review was to survey the available literature on titanium bonding systems, focusing on the adhesive monomer in the luting agent in order to expand the application of resin-bonded fixed prostheses made of titanium or titanium alloys. It was found that adhesive monomers are effective for bonding to titanium, and provide results equal to the procedures of silanization and tribochemical silica coating. A primer or a luting agent, including 10-methacryloyloxydecyl dihydrogen phosphate (MDP), methacryloyloxyalkyl thiophosphate derivative (MEPS), 6-methacryloxyhexyl phosphonoacetate (6-MHPA), and 4-methacryloyloxyethl trimellitate anhydride (4-META) promotes bonding characteristics between titanium and the resin material.
Topics: Alloys; Dental Bonding; Dental Cements; Materials Testing; Methacrylates; Resin Cements; Surface Properties; Titanium
PubMed: 35584941
DOI: 10.2334/josnusd.22-0036