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Federal Register Jun 2010The Food and Drug Administration (FDA) published a final rule in the Federal Register of August 4, 2009 (74 FR 38686) which classified dental amalgam as a class II...
Dental devices: classification of dental amalgam, reclassification of dental mercury, designation of special controls for dental amalgam, mercury, and amalgam alloy; technical amendment. Final rule; technical amendment.
The Food and Drug Administration (FDA) published a final rule in the Federal Register of August 4, 2009 (74 FR 38686) which classified dental amalgam as a class II device, reclassified dental mercury from class I to class II, and designated special controls for dental amalgam, mercury, and amalgam alloy. The effective date of the rule was November 2, 2009. The final rule was published with an inadvertent error in the codified section. This document corrects that error. This action is being taken to ensure the accuracy of the agency's regulations.
Topics: Dental Alloys; Dental Amalgam; Device Approval; Humans; Mercury; Mercury Compounds; United States
PubMed: 20540224
DOI: No ID Found -
International Journal of Oral and... Jul 2016The use of titanium implants is well documented and they have high survival and success rates. However, when used as reduced-diameter implants, the risk of fracture is... (Meta-Analysis)
Meta-Analysis Review
The use of titanium implants is well documented and they have high survival and success rates. However, when used as reduced-diameter implants, the risk of fracture is increased. Narrow diameter implants (NDIs) of titanium-zirconium (Ti-Zr) alloy have recently been developed (Roxolid; Institut Straumann AG). Ti-Zr alloys (two highly biocompatible materials) demonstrate higher tensile strength than commercially pure titanium. The aim of this systematic review was to summarize the existing clinical evidence on dental NDIs made from Ti-Zr. A systematic literature search was performed using the Medline database to find relevant articles on clinical studies published in the English language up to December 2014. Nine clinical studies using Ti-Zr implants were identified. Overall, 607 patients received 922 implants. The mean marginal bone loss was 0.36±0.06mm after 1 year and 0.41±0.09mm after 2 years. The follow-up period ranged from 3 to 36 months. Mean survival and success rates were 98.4% and 97.8% at 1 year after implant placement and 97.7% and 97.3% at 2 years. Narrow diameter Ti-Zr dental implants show survival and success rates comparable to regular diameter titanium implants (>95%) in the short term. Long-term follow-up clinical data are needed to confirm the excellent clinical performance of these implants.
Topics: Dental Alloys; Dental Implants; Dental Prosthesis Design; Humans; Materials Testing; Tensile Strength; Titanium; Zirconium
PubMed: 26852292
DOI: 10.1016/j.ijom.2016.01.004 -
Brazilian Dental Journal 2012The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods....
The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.
Topics: Corrosion; Dental Alloys; Dielectric Spectroscopy; Electrochemistry; Ions; Potentiometry; Saliva, Artificial; Surface Properties
PubMed: 22666772
DOI: 10.1590/s0103-64402012000200009 -
Srpski Arhiv Za Celokupno Lekarstvo 2016Increases in market prices of gold over the last 20 years have led to expansion of basic dental alloys, which, primarily due to their good mechanical properties and...
INTRODUCTION
Increases in market prices of gold over the last 20 years have led to expansion of basic dental alloys, which, primarily due to their good mechanical properties and acceptable prices, have found their place in everyday dental practice. However, within the procedure of making dental prosthetic restorations, the alloys are melted and cast, which leads to changes in their physical, mechanical and biological properties.
OBJECTIVE
The objective of the study was to test biocompatibility of a Ni-Cr dental alloy (WIRON 99) depending on the number of melting and casting processes.
METHODS
The working method included the testing of cytotoxicity of the alloy obtained by casting after one, after four, and after eight successive processes of melting. Cytotoxicity of samples was tested by means of a 24-hour and a three-day cytotoxicity test, done on L929 fibroblasts.
RESULTS
A repeatedly melted and cast alloy shows a reduced biocompatibility and causes specific responses of the tissues in the surrounding area. Since the cytotoxic effect is more significant in the extended contact with the culture cells, a three-day cytotoxicity test showed discrete changes which were the indicator of cell growth inhibition in the cell culture.
CONCLUSION
The obtained results confirm the working hypothesis that repeated alloy melting and casting will decrease biocompatibility of dental alloys and will lead to specific responses of the tissue in the surrounding area.
Topics: Biocompatible Materials; Chromium Alloys; Dental Alloys; Humans; Materials Testing; Nickel; Surface Properties; Toxicity Tests
PubMed: 29659215
DOI: No ID Found -
Zhejiang Da Xue Xue Bao. Yi Xue Ban =... May 2009Magnetic resonance imaging (MRI) technique is one of the most commonly used imaging diagnostic techniques for pate diseases at present.Metal and alloy are commonly used... (Review)
Review
Magnetic resonance imaging (MRI) technique is one of the most commonly used imaging diagnostic techniques for pate diseases at present.Metal and alloy are commonly used in dental practice. The artifacts on MRI caused by metal and alloy may result in attenuation of signal intensity, image distortion and signal loss, which severely influences imaging quality. So these materials confine the application of MRI on pate. In this paper, the influence of dental metallic materials on MRI is discussed. It expounds the generation and principals of MR artifacts, the influence of artifacts of metal dental prosthetic restoration, the effects of choosing different MR sequences and imaging weight on MRI, as well as how to prevent and diminish artifacts, to provide reference for clinical practice.
Topics: Artifacts; Brain; Dental Alloys; Humans; Magnetic Resonance Imaging
PubMed: 19504645
DOI: 10.3785/j.issn.1008-9292.2009.03.018 -
Lasers in Medical Science Nov 2010The aim was to evaluate the mechanical properties and porcelain bonded strength of nickel-chromium (Ni-Cr) dental alloy fabricated by laser rapid forming (LRF). The...
The aim was to evaluate the mechanical properties and porcelain bonded strength of nickel-chromium (Ni-Cr) dental alloy fabricated by laser rapid forming (LRF). The tensile properties and porcelain bonded strengths of LRF Ni-Cr dental alloy were evaluated by tensile tests (five specimens per group) and three-point bending tests (ten specimens per group). The same tests for the cast Ni-Cr dental alloy were used as for the control. The microstructure and the bonding interface of the metal substrate to porcelain were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The tensile strength of LRF Ni-Cr dental alloy (840 MPa) was superior to that of the cast Ni-Cr alloy (670 MPa), but the ductility had decreased. The porcelain bonded strength of LRF Ni-Cr dental alloy was 44.7 MPa, which was also superior to that of the cast Ni-Cr dental alloy (41.6 MPa). According to analysis by Student's t-test, the porcelain bonded strengths of the Ni-Cr dental alloy presented statistically significant differences between the groups of LRF and cast alloy (P < 0.05), but the porcelain bonded strengths were all above the acceptable value required by the International Organization for Standardization (ISO) standard 9693 (25 MPa). The coefficient of thermal expansion (CTE, mean value of five specimens) of LRF Ni-Cr dental alloy (14 x 10(-6) degrees C(-1)) was higher than that (13.7 x 10(-6) degrees C(-1)) of the cast Ni-Cr dental alloy. Both LRF and cast Ni-Cr dental alloy had positive Deltaalpha, not exceeding the maximum difference (1 x 10(-6) degrees C(-1)) in CTE. SEM and EDS results showed that all the specimens measured for porcelain bonded strength and prepared from the LRF and cast Ni-Cr alloy exhibited a mixed mode of cohesive and adhesive failure. Evaluation of the mechanical properties and porcelain bonded strengths of LRF Ni-Cr alloy revealed that both superior tensile and porcelain bonded properties can be obtained. With improvement of the technique, it is hoped that the LRF Ni-Cr dental alloy could be a good alternative to the conventional cast Ni-Cr dental alloy in the future.
Topics: Biomechanical Phenomena; Chromium Alloys; Dental Stress Analysis; Humans; In Vitro Techniques; Lasers; Light-Curing of Dental Adhesives; Materials Testing; Metal Ceramic Alloys; Microscopy, Electron, Scanning; Spectrometry, X-Ray Emission; Surface Properties; Tensile Strength
PubMed: 19548056
DOI: 10.1007/s10103-009-0690-3 -
Hellenika Stomatologika Chronika.... 1988In 51 individuals with dental caries (mean age +/- SE, 30, 12 +/- 1, 43) were determined the serum's immunoglobulins IgA, IgG, IgM and the ration IgG/IgA. The levels of... (Comparative Study)
Comparative Study
In 51 individuals with dental caries (mean age +/- SE, 30, 12 +/- 1, 43) were determined the serum's immunoglobulins IgA, IgG, IgM and the ration IgG/IgA. The levels of them were compared with the levels of immunoglobulins of 53 individuals (mean age +/- SE 36, 78 +/- 1, 86) with no significant difference (p greater than 0.1). Also, no significant difference (p greater than 0.1) was observed between the levels of immunoglobulins of the two subgroups, one with dental caries only (n = 32) and another with dental caries and alloy (n = 19). When in the two subgroups was taken care the dental caries degree the mean levels of the above parameters were differenciated. The mean level of IgG was significant lower in the subgroup with high caries degree without alloy (p less than 0.01) comparing with low caries degree. This difference was not observed between the subgroups where there was dental alloy. Also lower mean level of IgA was observed in the subgroup with high caries experience without prosthesis in contrast with the subgroup where there was dental alloy where the mean level of IgA was higher comparing these with the corresponding comparing subgroups. These differences were not significant (p greater than 0.1). The charge of the IgG/IgA ration was similarly lower in the subgroup with or without dental alloy. Also no significant was found between the levels of IgA, IgG, IgM, in relation to preexisting dental alloy or not. Our results show that the levels of IgA, IgG, IgM, can be affected not only of the dental caries degree but also of the preexisting dental alloy.
Topics: Adult; Dental Alloys; Dental Caries; Humans; Immunoglobulin Isotypes
PubMed: 3153687
DOI: No ID Found -
The Journal of Prosthetic Dentistry Jul 2016The pH level of the oral environment influences corrosion in dental materials. Corrosion behaviors of Co-Cr-Mo and Co-Cr-Mo-Ni alloys in different pH environments remain...
STATEMENT OF PROBLEM
The pH level of the oral environment influences corrosion in dental materials. Corrosion behaviors of Co-Cr-Mo and Co-Cr-Mo-Ni alloys in different pH environments remain undetermined.
PURPOSE
The purpose of this in vitro study was to evaluate the surface properties and corrosion behaviors of Co-Cr-Mo and Co-Cr-Mo-Ni dental casting alloys in artificial saliva at pH values of 5.0 and 2.5.
MATERIAL AND METHODS
Fifty specimens were divided into 2 groups according to the alloy composition. The surface compositions, hardness values, and microstructures of the alloys were measured before immersion in artificial saliva. The corrosion behaviors of the specimens in artificial saliva at pH values of 5.0 and 2.5 were studied using electrochemical impedance spectroscopy (EIS). The microstructures were examined again after a 7-day immersion test. Data were analyzed by a 1-way analysis of variance (ANOVA) test (α=.05).
RESULTS
As expected, the relative levels of Co and Cr of the surface composition were higher in the Co-Cr-Mo alloy. The Co-Cr-Mo alloy had statistically higher surface hardness than the Co-Cr-Mo-Ni alloy (P<.05). In the pH 2.5 environment, both of the alloys showed decreased corrosion resistance (P<.05). The microstructure of the Co-Cr-Mo-Ni alloy corroded more than that of the Co-Cr-Mo alloy in the pH 2.5 environment. The oxide-layer corrosion resistance of the Co-Cr-Mo alloy was better than that of the Co-Cr-Mo-Ni alloy in Fusayama artificial saliva solutions at pH values of both 5.0 and 2.5 (P<.05).
CONCLUSIONS
The corrosion resistance of the Co-Cr-Mo alloy was better in the oral environment, especially at a low pH value.
Topics: Corrosion; Dental Alloys; Dental Casting Technique; Denture, Partial, Removable; Electric Impedance; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Nickel; Surface Properties; Vitallium
PubMed: 26822710
DOI: 10.1016/j.prosdent.2015.12.001 -
Journal of Nanoscience and... Apr 2017Porcelain-fused-to-metal crown is one of the widely-used prostheses among the dental porcelain restorations. Nonprecious metals like Ni–Cr and Co–Cr have extensively...
Porcelain-fused-to-metal crown is one of the widely-used prostheses among the dental porcelain restorations. Nonprecious metals like Ni–Cr and Co–Cr have extensively been used for metal-ceramic restorations due to advantages such as inexpensive price, hardness, durability, resistance to deformation, thin thickness of metal of porcelain area, and other mechanical and physical properties. However, the immediate advantage of the Co–Cr alloy is comparable performance to other base metal alloys, but without an allergenic nickel component. To achieve clinical longevity of porcelain-fused-to-metal (PFM) crowns, it is essential to have adequate bond strength between the metal substrate and porcelain. Any type of metal-ceramic fracture failure can become a costly and timeconsuming problem, both in the clinic and laboratory. Therefore, the suitability of the Co–Cr alloy for dental applications is critically associated with its ceramic bonding capacity. In this study, Co–Cr metal alloys modified by acid-etching and sandblasting, oxide layer was formed for subsequent bonding to porcelain ceramics. By both acid-etching and sandblasting oxide layer was formed and showed higher bonding strength at a proper condition, but debonding was occurred at porcelain layer so that they showed highest bonding strength by combined these two kind of surface treatment. Because the oxide film was formed more densely in a vacuum at the portions where more sophisticated concavo-convex were formed on the surface of a metal.
Topics: Chromium Alloys; Dental Alloys; Dental Bonding; Dental Porcelain; Materials Testing; Nickel; Oxides
PubMed: 29659213
DOI: 10.1166/jnn.2017.13313 -
Journal of Prosthodontics : Official... Jun 2015The aim of this study was to review the effect of selective laser melting (SLM) procedure on the properties of dental structures made of Co-Cr alloys and to evaluate its... (Review)
Review
PURPOSE
The aim of this study was to review the effect of selective laser melting (SLM) procedure on the properties of dental structures made of Co-Cr alloys and to evaluate its quality and compare it to those produced by conventional casting and milling fabrication techniques.
MATERIALS AND METHODS
A computerized database search using PubMed and Scopus was conducted for peer-reviewed scientific research studies regarding the use of SLM in Co-Cr dental alloys with no restrictions for publication years. The search engines provided hundreds of results, and only 48 scientific research papers, case studies, or literature reviews were considered relevant for this review.
RESULTS
The innovative manufacturing concept of SLM offers many advantages compared with casting and milling fabrication techniques. SLM provides different microstructure from casting and milling with minimal internal porosity and internal fitting, marginal adaptation, and comparable bond strength to porcelain. Mechanical and electrochemical properties of SLM structures are enhanced compared to cast, while clinical longevity of single-metal ceramic crowns is comparable to Au-Pt dental alloy.
CONCLUSION
The SLM technique provides dental prosthetic restorations more quickly and less expensively without compromising their quality compared with restorations prepared by casting and milling techniques.
CLINICAL SIGNIFICANCE
The current SLM devices provide metallic restorations made of Co-Cr alloys for removable and fixed partial dentures without compromising the alloy or restoration properties at a fraction of the time and cost, showing great potential to replace the aforementioned fabrication techniques in the long term; however, further clinical studies are essential to increase the acceptance of this technology by the worldwide dental community.
Topics: Chromium Alloys; Dental Alloys; Dental Casting Technique; Dental Porcelain; Humans; Materials Testing; Metal Ceramic Alloys; Surface Properties
PubMed: 26129918
DOI: 10.1111/jopr.12268