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Dental Materials Journal 2015This study investigated high-cycle fatigue behavior in three β-Ti wires (TMA, Resolve, Gummetal). Fatigue was evaluated using a static three-point bending test and a...
This study investigated high-cycle fatigue behavior in three β-Ti wires (TMA, Resolve, Gummetal). Fatigue was evaluated using a static three-point bending test and a high-cycle fatigue test with a three-point bending mode. The surfaces of fractured wires were observed with scanning electron microscopy, and the post-fatigue crystal structures were determined by micro-X-ray diffraction. The Gummetal wire exhibited the lowest elastic modulus, bending strength and fatigue limit, and exhibited the highest resilience of the three types of wire studied. However, no difference in the number of cycles to failure was observed among the three types of wire. The fatigue crack propagation and rapid propagation regions of all wires contained single-phase β-Ti. The elastic modulus and bending strength influenced the fatigue limit, although these properties did not affect the number of cycles to fracture. The three types of β-Ti wires exhibited similar risks of wire fracture.
Topics: Dental Alloys; Dental Stress Analysis; Elasticity; Equipment Failure; Humans; Materials Testing; Microscopy, Electron, Scanning; Orthodontic Wires; Stress, Mechanical; Surface Properties; Titanium
PubMed: 25740165
DOI: 10.4012/dmj.2014-012 -
Dento Maxillo Facial Radiology 2015To assess the safety of different magnetic dental attachments during 3-T MRI according to the American Society for Testing and Materials F2182-09 and F2052-06e1 standard...
OBJECTIVES
To assess the safety of different magnetic dental attachments during 3-T MRI according to the American Society for Testing and Materials F2182-09 and F2052-06e1 standard testing methods and to develop a method to determine MRI compatibility by measuring magnetically induced torque.
METHODS
The temperature elevations, magnetically induced forces and torques of a ferromagnetic stainless steel keeper, a coping comprising a keeper and a cast magnetic alloy coping were measured on MRI systems.
RESULTS
The coping comprising a keeper demonstrated the maximum temperature increase (1.42 °C) for the whole-body-averaged specific absorption rate and was calculated as 2.1 W kg⁻¹ with the saline phantom. All deflection angles exceeded 45°. The cast magnetic alloy coping had the greatest deflection force (0.33 N) during 3-T MRI and torque (1.015 mN m) during 0.3-T MRI.
CONCLUSIONS
The tested devices showed minimal radiofrequency (RF)-induced heating in a 3-T MR environment, but the cast magnetic alloy coping showed a magnetically induced deflection force and torque approximately eight times that of the keepers. For safety, magnetic dental attachments should be inspected before and after MRI and large prostheses containing cast magnetic alloy should be removed. Although magnetic dental attachments may pose no great risk of RF-induced heating or magnetically induced torque during 3-T MRI, their magnetically induced deflection forces tended to exceed acceptable limits. Therefore, the inspection of such devices before and after MRI is important for patient safety.
Topics: Dental Alloys; Dental Prosthesis; Equipment Safety; Magnetic Phenomena; Magnetic Resonance Imaging; Phantoms, Imaging; Radio Waves; Temperature; Torque
PubMed: 25785821
DOI: 10.1259/dmfr.20150011 -
Brazilian Dental Journal 2007Dentists and technicians have used dental ceramics associated with different types of alloys without taking into account the characteristics of compatibility of these... (Comparative Study)
Comparative Study
Dentists and technicians have used dental ceramics associated with different types of alloys without taking into account the characteristics of compatibility of these materials. Knowing the properties of the alloy and ceramic used in metal/ceramic restorations is a key factor for treatment success. The purpose of this study was to evaluate the bond strength of a palladium-silver alloy (Pors-on 4) to 3 ceramics (Ceramco, Noritake and Vita VMK-68) using shear forces at the metal-ceramic interface. A stainless steel cylindrical matrix was used for preparation of the metal dies, application of ceramic and shear strength testing. Thirty palladium-silver alloy cylinders received two layers of opaque and two layers of body porcelain, and shear tests were performed in a universal testing machine at a cross-head speed of 0.5 mm/min. Shear bond strength means (in MPa) were: 28.21(Ceramco), 28.96 (Noritake) and 24.11 (Vita VMK-68). One-way ANOVA did not show statistically significant differences (p>0.05) among the materials. The results of this study indicate that the three evaluated ceramic systems are suitable to be used in combination with the tested palladium-silver alloy.
Topics: Analysis of Variance; Dental Alloys; Dental Bonding; Dental Porcelain; Dental Stress Analysis; Palladium; Shear Strength; Silver; Stress, Mechanical
PubMed: 18176717
DOI: 10.1590/s0103-64402007000300012 -
PloS One 2023The durability of dental restorations is highly determined by an accurate marginal fit, which is in turn affected by the high temperature of porcelain firing....
The durability of dental restorations is highly determined by an accurate marginal fit, which is in turn affected by the high temperature of porcelain firing. Information is inadequate about the marginal adaptation of metal-ceramic restorations fabricated by soft metal milling technologies after repeated firings. This study aimed to compare the effect of repeated ceramic firings on the marginal fit of copings fabricated from cobalt-chromium through soft metal milling and a conventional nickel-chromium casting alloy. A single standard brass die was designed, machined, and scanned, based on which, 20 frameworks were designed and fabricated through either soft metal milling or conventional casting (n = 10 per group) and porcelain veneered. The vertical marginal fit of the metal copings was measured after 3, 5, and 7 firing cycles by using a digital microscope on 16 points around the finish line of the metal die at ×80 magnification. The data were analyzed through repeated measures ANOVA and independent t-test (α = 0.05). The marginal fit of neither metal group was significantly affected by the number of firing cycles (P = 0.747). However, the marginal discrepancy was statistically lower in the soft metal milling group than that in the casting group (P<0.001). Repeated porcelain firings did not significantly affect the marginal fit of either alloy and remained within the clinically acceptable range after firings. However, the milled alloy had superior marginal fit regardless of the number of firing cycles.
Topics: Dental Porcelain; Computer-Aided Design; Metal Ceramic Alloys; Chromium Alloys; Cobalt; Chromium; Dental Prosthesis Design
PubMed: 37874843
DOI: 10.1371/journal.pone.0275374 -
The Angle Orthodontist Sep 2013To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi... (Comparative Study)
Comparative Study
OBJECTIVE
To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi with that of beta titanium alloy in physiological solution with and without addition of fluoride.
MATERIALS AND METHODS
NiTi corrosion resistance was investigated through electrochemical impedance spectroscopy and anodic polarization in sodium chloride (NaCl 0.15 M) with and without addition of 0.02 M sodium fluoride (NaF), and the results were compared with those associated with beta titanium. The influence of fluoride concentration on NiTi corrosion behavior was assessed in NaCl (0.15 M) with and without 0.02, 0.04, 0.05, 0.07, and 0.12 M NaF solution. Galvanic corrosion between NiTi and beta titanium were investigated. All samples were characterized by scanning electron microscopy.
RESULTS
Polarization resistance decreased when NaF concentration was increased, and, depending on NaF concentration, NiTi can suffer localized or generalized corrosion. In NaCl solution with 0.02 M NaF, NiTi suffer localized corrosion, while beta titanium alloys remained passive. Current values near zero were observed by galvanic coupling of NiTi and beta titanium.
CONCLUSIONS
There is a decrease in NiTi corrosion resistance in the presence of fluoride. The corrosion behavior of NiTi alloy depends on fluoride concentration. When 0.02 and 0.04 M of NaF were added to the NaCl solution, NiTi presented localized corrosion. When NaF concentration increased to 0.05, 0.07, and 0.12 M, the alloy presented general corrosion. NiTi corrosion resistance behavior is lower than that of beta titanium. Galvanic coupling of these alloys does not increase corrosion rates.
Topics: Corrosion; Dental Alloys; Dielectric Spectroscopy; Materials Testing; Nickel; Orthodontic Wires; Sodium Chloride; Sodium Fluoride; Titanium
PubMed: 23448158
DOI: 10.2319/091712-740.1 -
Progress in Orthodontics Dec 2016The aim of this study is to investigate the relative stiffness of straight and mushroom lingual archwires of different diameters, cross sections and alloys, plotting...
BACKGROUND
The aim of this study is to investigate the relative stiffness of straight and mushroom lingual archwires of different diameters, cross sections and alloys, plotting their load/deflection graphs and using a modified three-point bending test.
METHODS
Fujita's mushroom archwires and straight lingual archwires of different diameters, cross sections and alloys were derived by a virtual set-up of an equal malocclusion and were cut at their straight distal portion. These distal portions were tested using a modified three-point bending test by an Instron 4467 dynamometer and the forces, were exerted at 1-mm deflection and were compared on each resulting load/deflection curve by means of ANOVA (p < 0.05).
RESULTS
All upper lingual mushroom wires exerted significantly lower forces than the straight wire. Lower mushroom archwires were stiffer than their upper counterparts, which were longer and featured inset bends. In the lower arch, similar levels of forces were recorded for the two types of wire. Load-deflection curves were higher for the straight wires, and stiffness increased proportionally with their diameter.
CONCLUSIONS
The stiffness of an archwire is a function of its diameter, length and the alloy it is made from. In lower lingual wires, there is little difference in stiffness between mushroom and straight wires, but in upper wires, the straight version is considerably stiffer. The greater bearing effect exhibited by the straight wire in the working and finishing phases makes it less susceptible to bowing effect and therefore preferable for sliding mechanics during en masse retraction, particularly in the upper arch.
Topics: Dental Alloys; Dental Stress Analysis; Elasticity; Finite Element Analysis; Humans; Materials Testing; Orthodontic Brackets; Orthodontic Wires; Stainless Steel; Stress, Mechanical
PubMed: 27593408
DOI: 10.1186/s40510-016-0140-2 -
Dento Maxillo Facial Radiology 2013To estimate the risk of injury from radiofrequency (RF) heating of metallic dental devices in use during 3.0 T MRI.
OBJECTIVES
To estimate the risk of injury from radiofrequency (RF) heating of metallic dental devices in use during 3.0 T MRI.
METHODS
The whole-body specific absorption rate (WB-SAR) was calculated on the basis of saline temperature elevation under the maximum RF irradiation for 15 min to determine the operation parameters for the heating test. The temperature changes of three types of three-unit bridges, a full-arch fixed dental prosthesis and an orthodontic appliance in use during MRI with a 3.0 T MR system (Magnetom(®) Verio; Siemens AG, Erlangen, Germany) were then tested in accordance with the American Society for Testing and Materials F2182-09 standardized procedure under the maximum RF heating during 15 min RF irradiation.
RESULTS
The system console-predicted WB-SAR was approximately 1.4 W kg(-1) and that measured with a saline phantom was 2.1 W kg(-1). In the assessment of RF heating, the highest temperature increase was +1.80 °C in the bridges, +1.59 °C in the full-arch fixed dental prosthesis and +2.61 °C in the orthodontic appliance.
CONCLUSIONS
The relatively minor RF heating of dental casting material-based prostheses in Magnetom Verio systems in the normal operating mode should not pose a risk to patients. However, orthodontic appliances may exhibit RF heating above the industrial standard (CENELEC standard prEN45502-2-3); therefore, the wire should be removed from the bracket or a spacer should be used between the appliance and the oral mucosa during MRI.
Topics: Chromium Alloys; Dental Alloys; Denture, Complete; Denture, Partial, Fixed; Gold Alloys; Hot Temperature; Magnetic Resonance Imaging; Orthodontic Appliances; Phantoms, Imaging; Sodium Chloride; Stainless Steel; Whole-Body Irradiation
PubMed: 23520391
DOI: 10.1259/dmfr.20120234 -
Dental Materials Journal Oct 2010Metal ions released in 1% lactic acid solution from combinations of titanium fixtures with superstructures made of dental precious metal alloys (dental alloys) and... (Comparative Study)
Comparative Study
Metal ions released in 1% lactic acid solution from combinations of titanium fixtures with superstructures made of dental precious metal alloys (dental alloys) and titanium and differences based on the fixing method were investigated. In combinations of titanium with dental alloys, the level of Ti release was influenced by micro-structure of titanium: it was lower when the grain size was smaller. In titanium-titanium combinations, differences in the micro-structure of metal also markedly influenced the dissolution: the level of release increased when the micro-structure of titanium was different. The Ti and V release levels were higher in combination with titanium alloy and titanium than with titanium alloy and dental alloys. Regarding the superstructure-fixture fixing method, the level of Ti release was significantly lower in cement than in direct fixation.
Topics: Alloys; Cementation; Color; Copper; Corrosion; Dental Abutments; Dental Alloys; Dental Cements; Dental Implants; Dental Materials; Dental Prosthesis Design; Gallium; Gold Alloys; Humans; Indium; Lactic Acid; Materials Testing; Metal Ceramic Alloys; Palladium; Particle Size; Silver; Solubility; Surface Properties; Tin; Titanium; Zinc
PubMed: 20823622
DOI: 10.4012/dmj.2010-005 -
Progress in Orthodontics Dec 2021Although preformed archwires with a variety of arch forms are currently commercially available, the effects of variation in the shape of these archwires on the...
BACKGROUND
Although preformed archwires with a variety of arch forms are currently commercially available, the effects of variation in the shape of these archwires on the orthodontic force at each tooth are not well understood. Therefore, we evaluated the forces delivered by various types of commercially available preformed nickel-titanium alloy (NiTi) archwires in a simulated mandibular dental arch.
METHODS
Sixty-three types of 0.019 × 0.025-inch preformed NiTi archwires from 15 manufactures were selected for analysis. The intercanine width (ICW) and intermolar width (IMW) of each archwire were measured at the mean canine and first molar depths of 30 untreated subjects with normal occlusions. Each archwire was placed in a multi-sensor measurement system simulating the mandibular dental arch of subjects with normal occlusions, and orthodontic forces in the facial-lingual direction at the central incisors, canines, and first molars were measured. Correlations between the ICW, IMW, and ICW/IMW ratio of archwires and the delivered forces were analyzed. The archwires were classified into the following four groups according to the ICW and IMW: Control group, ICW and IMW are within the means ± standard deviations of the normal ranges; Ovoid group, narrow ICW and IMW; Tapered group, narrow ICW; and Square group, narrow IMW. The forces were compared among these groups for each tooth.
RESULTS
Significant correlations between the measured archwire width and force to each tooth were found, except between IMW and forces at the central incisors and canines. Significant differences in the forces were found among all groups, except between the Ovoid and Tapered groups at all teeth and between the Ovoid/Tapered and Control groups at the first molar. Significantly greater orthodontic forces in the facial direction were delivered at the central incisors by the archwires in the Ovoid and Tapered groups when compared with the archwires in the other groups.
CONCLUSION
These findings suggest that there is a possible risk of a clinically significant level of unfavorable orthodontic force being delivered to the mandibular incisors in labial inclination when using a preformed archwire with an ICW that is narrower than the dental arch.
Topics: Dental Alloys; Dental Arch; Humans; Nickel; Orthodontic Wires; Titanium
PubMed: 34850299
DOI: 10.1186/s40510-021-00385-1 -
Journal of the Mechanical Behavior of... Jun 2023The authors have been using improved superelastic Nickel-Titanium alloy wire (ISW) to close and align extraction spaces simultaneously, instead of separately using rigid...
PURPOSE
The authors have been using improved superelastic Nickel-Titanium alloy wire (ISW) to close and align extraction spaces simultaneously, instead of separately using rigid wires for closing extraction spaces and Ni-Ti alloy wires for leveling and aligning. ISW has a low stiffness, which makes it challenging to generate sufficient moments. This study aimed to demonstrate the forces and moments exerted on adjacent brackets using an orthodontic simulator (OSIM) attached to a high-precision 6-axis sensor.
MATERIALS AND METHODS
In experiment 1, a 0.016 × 0.022-inch ISW, stainless steel (SS) wire, and β-titanium wires were ligatured into the two brackets. The 0.018 × 0.025-inch slot self-ligating brackets were bonded to two simulated teeth at the same height, and the experiment was conducted using the high-precision OSIM. The distance between the brackets was 10 mm, the V-bend angles of the installed wires were 10°, 20°, 30°, and 40°, and the apex position was set at the center of the bracket. In experiment 2, 6.0- and 9.0-mm long elastomeric chains were placed on the same brackets as in Experiment 1 to measure forces and moments. The distance between the brackets was increased by 1.0 mm from 6.0 to 15.0 mm. Both experiments were conducted in a 37 °C thermostatic chamber similar to the oral environment.
RESULTS AND DISCUSSION
In experiment 1, we measured moments on both sides for all the wires. As the V-bend angle increased, the absolute values of the moments also increased. With a V-bend angle of 10°, there was a significant (p < 0.05) difference in the moment generated in the left and right brackets among the three wire types. In the ISW, -1.67 ± 0.38 N・mm was generated in the left bracket, while 0.38 ± 0.26 N・mm was generated in the right bracket at 10°. At 20°, -1.77 ± 0.69 N・mm was generated in the left bracket, while 2.37 ± 0.94 N・mm was generated in the right bracket. At 30°, -2.98 ± 0.49 N・mm was generated in the left bracket, while 3.25 ± 0.32 N・mm was generated in the right bracket. Moreover, at 40°, -3.96 ± 0.58 N・mm was generated in the left bracket, while 3.55 ± 0.53 N・mm was generated in the right bracket. Furthermore, in experiment 2, the moments increased in proportion to the increase in distance between the centers of the two brackets. Absolute values of the moments were approximately equal for the left and right brackets. The 6.0-mm elastomeric chain generated a minimum force of -0.09 ± 0.05 N in the left direction when the distance between brackets was 6.0 mm, while a maximum of 1.24 ± 0.3 N when the distance between brackets was 12 mm in the right bracket. In the left bracket, minimum and maximum forces of -0.09 ± 0.07 and 1.3 ± 0.4 N were generated in the right direction, respectively. The 9.0-mm elastomeric chain generated a minimum force of 0.03 ± 0.07 N in the left direction when the distance between brackets was 9.0 mm, while a maximum of 1.3 ± 0.1 N when the distance between brackets was 15 mm in the right bracket. In the left bracket, minimum and maximum forces of 0.05 ± 0.06 and 0.98 ± 0.2 N were generated in the right direction, respectively.
CONCLUSION
Mechanical data of the ISW have been collected in the study, which was previously difficult to perform owing to the low stiffness of the wire. It is suggested that the ISW can provide sufficient moments with the addition of V-bends to close the space by bodily movement.
Topics: Alloys; Titanium; Orthodontic Wires; Orthodontic Brackets; Torque; Stainless Steel; Dental Stress Analysis; Materials Testing; Dental Alloys
PubMed: 37146519
DOI: 10.1016/j.jmbbm.2023.105861