Search

Legislative framework addresses the issues of alloy corrosion, demanding the restricted use of probable carcinogenic, mutagenic, and toxic-for-human-reproduction (CMG) metals like nickel, cobalt, and chromium and demanding the development of new biomaterials. The aim of this research was to evaluate and compare the ion release of standard dental alloys and their hypoallergenic equivalents. Six types of orthodontic alloy wires (nickel–titanium (NiTi), coated NiTi, stainless steel (SS), Ni-free SS, and cobalt–chromium (CoCr) and titanium–molybdenum (TMA) were immersed into artificial saliva of pH 5.5 and 6.6. Release of metal ions was measured by inductively coupled plasma–mass spectrometry after 3, 7, 14 and 28 days. The data were analyzed using analysis of variance, and results with p < 0.05 were considered significant. NiTi released more Ti and Ni ions compared to the coated NiTi; SS released more iron, chromium, and nickel compared to the nickel-free SS. CoCr released cobalt in a high concentration and low amounts of chromium, nickel, and molybdenum compared to the molybdenum and titanium released by TMA. Release of metals from dental orthodontic alloys in vitro was overall lower at pH 6.6 and for the hypoallergenic equivalents when compared to standard dental alloys. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to compare the shaping abilities of different nickel-titanium file systems. Materials and Methods: Sixty-six j-shaped resin blocks were randomly divided into three groups (n = 22): Group T-Endo MUST (TE), Group WaveOne (W), Group TruNatomy (TR). After canal preparation, the amount of material removed from the canal, the centering ratio of the file systems, the direction and amount of canal transportation, and shaping errors were evaluated. Shaping time was calculated. Data of shaping time were analyzed with ANOVA and Tamhane test. Data on the shaping ability were analyzed with two- and three-way ROBUST ANOVA. The significance level was set at p = 0.05. Results: There was a statistically significant difference between all groups for shaping time (p < 0.001). There was a statistically significant difference between groups for the total amount of material removed (p < 0.001). The directions of canal transportation were the inner surface of the curvature for W and TR and the outer for TE. There was no statistically significant difference between the groups for the amount of transportation (p > 0.05). The centering ratio of TE and W was statistically higher than TruNatomy (p < 0.001). Conclusions: TruNatomy removed the least material that supported the minimally invasive endodontic approach. All file systems caused similar transportation and did not change the original canal shape. [ABSTRACT FROM AUTHOR]

The sliding wear of Ti-6Al-4V alloys coexisting with dental amalgam in a simulated temperature-controlled cell was evaluated. Disc-shaped samples of Ti-6Al-4V (n = 30) and spherical silver amalgam (n = 30) were prepared. Discs were subjected to wear while immersed in artificial and fluoridated saliva as follows: Ti-6Al-4V–Ti-6Al-4V (G1); amalgam–amalgam (G2), and Ti-6Al-4V–amalgam (G3). Samples were analyzed for mass variation, volume loss, and surface roughness. Wear tracks were characterized by scanning electron microscopy. Wearing induced significant mass loss for all groups except G3 in fluoridated saliva: Ti-6Al-4V (p = 0.045) and amalgam (p = 0.732). These samples presented an increase in mean surface roughness (p = 0.032 and 0.010, respectively). Overall, Ti-6Al-4V showed 0.07 mm3 (95% CI: [0.06–0.07]) higher wear track volume. Ti-6Al-4V has a higher mass loss when subjected to fluoridated media but no significant roughness variation. Fluor-containing substances should be avoided over Ti-6Al-4V alloys placed in areas of mechanical wear, especially if dental amalgam is also present. [ABSTRACT FROM AUTHOR]

Purpose This study aimed to compare the shaping abilities of different nickel-titanium file systems. Materials and Methods Sixty-six j-shaped resin blocks were randomly divided into three groups (n = 22): Group T-Endo MUST (TE), Group WaveOne (W), Group TruNatomy (TR). After canal preparation, the amount of material removed from the canal, the centering ratio of the file systems, the direction and amount of canal transportation, and shaping errors were evaluated. Shaping time was calculated. Data of shaping time were analyzed with ANOVA and Tamhane test. Data on the shaping ability were analyzed with two- and three-way ROBUST ANOVA. The significance level was set at p = 0.05. Results There was a statistically significant difference between all groups for shaping time (p 0.05). The centering ratio of TE and W was statistically higher than TruNatomy (p

Chromium- and cobalt-based alloys, as well as chrome–nickel steels, are most used in dental prosthetics. Unfortunately, these alloys, especially nickel-based alloys, can cause allergic reactions. A disadvantage of these alloys is also insufficient corrosion resistance. To improve the properties of these alloys, amorphous Si (C,N) coatings were deposited on the surfaces of metal specimens. This paper characterizes coatings of silicon carbide nitrides, deposited by the magnetron sputtering method on the surface of nickel–chromium alloys used in dental prosthetics. Depending on the deposition parameters, coatings with varying carbon to nitrogen ratios were obtained. The study analyzed their structure and chemical and phase composition. In addition, a study of surface wettability and surface roughness was performed. Based on the results obtained, it was found that amorphous coatings of Si (C,N) type with thicknesses of 2 to 4.5 µm were obtained. All obtained coatings increase the value of surface free energy. The study showed that Si (C,N)-type films can be used in dental prosthetics as protective coatings. [ABSTRACT FROM AUTHOR]

Introduction: Metal ions, released from dental alloys due to corrosion, come in contact with the cells of the surrounding tissues and may spread throughout the body via the gastrointestinal system, thus inducing dose-dependent cytopathological effects. This study aimed to assess and compare the salivary cobalt and chromium concentrations in individuals aged 18–65 years with and without dental restorations containing metal alloys. Methods: Participants were divided into two main groups according to the existence of metal alloys in the oral cavity—18 patients had fixed prosthetic restorations made of metal alloys, and 17 patients had no metal objects in their oral cavity. Each main group was subdivided into two subgroups according to the type of saliva sample—with or without additional stimulation. Salivary cobalt and chromium concentrations were measured by inductively coupled plasma mass spectrometry. A non-parametric Mann–Whitney test and Spearman’s rank correlation coefficient were applied, and the level of significance was set to p < 0.05. Results: The results showed that the chromium level in non-stimulated saliva was higher in the group of patients with metal dental restorations. No statistical difference was found in cobalt levels. There was no statistical difference in Co or Cr concentrations in stimulated saliva between the studied groups. A positive correlation was found between Cr and Co concentrations in non-stimulated saliva and between cobalt concentrations in stimulated and non-stimulated saliva. Conclusions: Metal alloys in the oral cavity induced elevated chromium levels in non-stimulated saliva, and a correlation between chromium and cobalt ion concentration was found. A detailed examination of patients and their medical history prior to prosthetic treatment is advisable in order to avoid any undesired health effects.

Objectives: The objective of this in vitro study was to evaluate the shear bond strength between the ceramic veneer and additively manufactured titanium with different surface treatments, and to compare with milled titanium. Also, to characterize the surface and the presence of an α‐case layer of additively manufactured and milled titanium. Material and Methods: Sixty additively manufactured titanium grade 23, and 20 milled titanium grade 4 cylindrical specimens were divided into four groups based on surface treatments, air‐particle abrasion and grinding. After ceramic veneering half of each group were thermocycled. The bond strength was analyzed using a shear bond strength test. The surfaces were analyzed using interferometry and scanning electron microscopy. Results: The grinding procedure and air‐particle abrading pressure had no significant effect on the shear bond strength (p =.264 and p =.344). Thermocycling showed a tendency towards an effect but not significant (p =.052). The group with the highest air‐abrading pressure showed the highest surface roughness. No presence of an α‐case layer was detected in any of the groups. Conclusion: Additively manufactured titanium grade 23 may be veneered with ceramics without prior grinding of the surfaces. [ABSTRACT FROM AUTHOR]

The interaction of different dental alloys with the oral environment may cause severe side effects (e.g., burning sensation, inflammatory reactions, carcinogenesis) as a result of oral galvanism. However, the pathogenesis of side effects associated with oral galvanism is still unclear, and the effects of direct current and alloy corrosion ions are considered potentially contributing factors. Therefore, the aim of this study was to systemically compare the damaging effects of (1) galvanism as a synergistic process (direct current + corrosion ions), (2) direct current separately, and (3) corrosion ions separately on an in vitro mucosa-like model based on a cell line of immortalized human keratinocytes (HaCaTs) to reveal the factors playing a pivotal role in dental alloys side effects. For this, we chose and compared the dental alloys with the highest risk of oral galvanism: Ti64–AgPd and NiCr–AgPd. We showed that galvanic current may be the leading damaging factor in the cytotoxic processes associated with galvanic coupling of metallic intraoral appliances in the oral cavity, especially in the short-term period (28 days). However, the contribution of corrosion ions (Ni2+) to the synergistic toxicity was also shown, and quite possibly, in the long term, it could be no less dangerous. [ABSTRACT FROM AUTHOR]

Abstract Objectives The objective of this in vitro study was to evaluate the shear bond strength between the ceramic veneer and additively manufactured titanium with different surface treatments, and to compare with milled titanium. Also, to characterize the surface and the presence of an α‐case layer of additively manufactured and milled titanium. Material and Methods Sixty additively manufactured titanium grade 23, and 20 milled titanium grade 4 cylindrical specimens were divided into four groups based on surface treatments, air‐particle abrasion and grinding. After ceramic veneering half of each group were thermocycled. The bond strength was analyzed using a shear bond strength test. The surfaces were analyzed using interferometry and scanning electron microscopy. Results The grinding procedure and air‐particle abrading pressure had no significant effect on the shear bond strength (p = .264 and p = .344). Thermocycling showed a tendency towards an effect but not significant (p = .052). The group with the highest air‐abrading pressure showed the highest surface roughness. No presence of an α‐case layer was detected in any of the groups. Conclusion Additively manufactured titanium grade 23 may be veneered with ceramics without prior grinding of the surfaces.

Copyright of dentalTarget is the property of dentalTarget and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 confirmed 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 subjects, of which 57.3% had a cast post. In the case of AT, discoloration 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. [ABSTRACT FROM AUTHOR]

Background. CAD/CAM technologies facilitate using powder CoCr alloys to produce metal-ceramic dental restorations. However, base alloys may induce oxidative stress in the oral cavity due to corrosion and ion release. This study evaluated resistance to corrosion and release of metal ions from 3D printed CoCr dental alloy and their effect on oral oxidative stress. Methods. Metal-ceramic crowns with 3D printed copings from CoCr alloy EOS CobaltChrome SP2 (EOS, Germany) were fabricated for 35 patients. Inductively coupled plasma mass spectrometry (ICP-MS) was used for measuring the concentration of Co and Cr ions in non-stimulated saliva before prosthetic treatment (BPT), at 2 h and 7 days after the dental treatment (APT2, APT7, respectively). Open circuit potentials (Eocp) were evaluated at APT2 and APT7. Estimating oral oxidative stress, measurements of 8-isoprostaglandin F2-alpha were conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS) at stages BPT, APT2, and APT7. Results. Salivary Co level increased at APT2 and decreased to the initial levels at APT7. No statistical difference was found between the levels of 8-isoPGF2-alpha measured, and between the Eocp measurements at APT2 and APT7. Conclusions. The studied alloy showed stable corrosion resistance and the metal ion release did not induce oral oxidative stress. [ABSTRACT FROM AUTHOR]

nema

In Purpose: The fabrication technique can influence the mechanical properties of Cobalt-Chromium (Co-Cr) dental alloys. Hence, the present study aims to determine the corrosion resistance and thermal expansion of alloys manufactured using three contemporary techniques. Material and Methods: A total of nine specimens of Co-Cr alloy were prepared according to ISO 22674 by each one of the three manufacturing processes (three in each process); conventional casting, direct metal laser sintering (DMLS) and milling (MIL). All these specimens were tested for coefficient of thermal expansion and corrosion resistance. The data was tabulated and analyzed statistically. Results: The difference in the thermal expansion of alloys fabricated using three techniques was non-significant at almost all the temperatures from 50 ºC to 950 ºC (p>0.05), except 450 ºC and 600 °C. The polarization resistance of specimens manufactured using the conventional method was more compared to DMLS and MIL at pH 5 (Conventional>MIL>DMLS) (p

Prosthetic rehabilitation of the maxillary front teeth is an extremely laborious problem for the dental team, consisting of the dentist and the dental technician. If for the physiognomic component the most recommended materials are the ceramic masses, for the resistance substrate there are several variants. Conventional technologies using dental alloys and modern ones involving the use of zirconium dioxide can be used successfully in performing fixed prosthetic restorations in the maxillary frontal area, both options having both advantages and disadvantages, as we will describe in this material.

Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys are widely used for dental applications. This research was aimed to investigate improvement in the mechanical properties of Ni-Cr-Mo alloy through Boron and Cerium doping. These alloys were doped with boron and boron+cerium alloying elements. The mechanical testing of the samples revealed that minor addition of these alloying elements significantly improved the ultimate tensile strength and yield strength. Moreover, the melting points of the doped samples, determined by differential thermal analysis, decreased appreciably with doping elements. Furthermore, detailed wear testing was carried out to analyze the in-situ behavior of the alloys. Significant improvement in wear rate was noted for the boron and boron+cerium added alloy samples. Also biocompatibility for the three alloys in cytotoxicity test proved the suitability for the use of these alloys in dental prostheses. [ABSTRACT FROM AUTHOR]

The electrochemical behaviour of alloys (Au50-Ag25-Pd25 and Ni88.6-Cr11.4) was studied in Fusayama's artificial saliva at pH 6.5 and 37 °C by using open circuit potential, electro­chemical impedance spectroscopy, and potentiodynamic polarization measure­ments. Electrochemical impedance spectroscopy results were simulated with an equivalent electrical circuit. After immersion in artificial saliva, surface characterization of samples was done using scanning electron microscopy connected with energy-dispersive spectro­scopy. All obtained results revealed that Au50-Ag25-Pd25 alloy is much more resistive than Ni88.6-Cr11.4 and can be recommended for the effective treatment of patients with dental prosthetics that have metal frameworks. s.

The interaction of different dental alloys with the oral environment may cause severe side effects (e.g., burning sensation, inflammatory reactions, carcinogenesis) as a result of oral galvanism. However, the pathogenesis of side effects associated with oral galvanism is still unclear, and the effects of direct current and alloy corrosion ions are considered potentially contributing factors. Therefore, the aim of this study was to systemically compare the damaging effects of (1) galvanism as a synergistic process (direct current + corrosion ions), (2) direct current separately, and (3) corrosion ions separately on an in vitro mucosa-like model based on a cell line of immortalized human keratinocytes (HaCaTs) to reveal the factors playing a pivotal role in dental alloys side effects. For this, we chose and compared the dental alloys with the highest risk of oral galvanism: Ti64–AgPd and NiCr–AgPd. We showed that galvanic current may be the leading damaging factor in the cytotoxic processes associated with galvanic coupling of metallic intraoral appliances in the oral cavity, especially in the short-term period (28 days). However, the contribution of corrosion ions (Ni2+) to the synergistic toxicity was also shown, and quite possibly, in the long term, it could be no less dangerous.

ObjectivesThe purpose of this study was to evaluate the effect of different ambient temperatures on cyclic fatigue (CF) life of two NiTi rotary systems and correlate the results with martensitic transformation temperatures.Materials and methodsHeat-treated NiTi Vortex Blue (VB) and EdgeSequel Sapphire (SP) instruments (tip sizes no. 20, 25, 30, 35, 40) were tested for CF resistance at room and body temperature (n = 20 each group) in a simulated canal (angle of curvature 60°; radius 3 mm; center from instrument tip 4.5 mm) with a motor controlled by an electric circuit. Mean half-life, beta and eta Weibull parameters were determined and compared. Two further instruments of each brand were subjected to differential scanning calorimetry (DSC).ResultsTemperature had an effect on fatigue behavior: all instruments lasted significantly longer at room than at body temperature. All VB significantly outlasted those of SP at body temperature; while smaller diameters of VB (size no. 20) were also significantly more resistant than SP when tested at room temperature; SP with larger diameters (sizes no. 30, no. 35, and no. 40) lasted significantly longer than VB did.ConclusionsImmersion in water at body temperature was associated with a marked decrease in the fatigue life of all rotary instruments tested. VB instruments were significantly more CF resistant at body temperature and showed the highest predictability in terms of fracture resistance.Clinical relevanceRotary instruments manufactured with different post-machining heat treatment responded differently to changed ambient temperatures. DSC assessment of martensitic conversion temperatures helps to predict the behavior of nickel titanium rotaries in different environments.

Co-Cr alloys are still used in metal-ceramic technology on the large scale. The purpose of this study was to provide a comparative analysis of the corrosion resistance by the polarization resistance technique of two Co-Cr-based alloys (codified Co-Cr- P and Co-Cr-PW) produced by the same manufacturer, which have a minor variation in chemical composition. Corrosion tests were performed at a temperature of 37 ± 0.5° C in a bath with heating and recirculation, in artificial saliva (SA) Carter Brugirard at pH = 7.58. Both tested alloys showed an increased corrosion resistance when immersed in artificial saliva, proving a good corrosion resistance and therefore a good biocompatibility. The Co-Cr-P test showed superior electrochemical values ​​and, implicitly, higher corrosion resistance.

The aim of this paper was to study the corrosion behavior of Nickel – Base – Dental Alloys in Ringer biological fluid. The Nickel base alloys are widely used for medical purposes, especially for prosthetic works in the field of dentistry. The applied electrochemical methods used for corrosion investigations are Open Circuit Potential, Linear Polarization during time of immersion in order to calculate the polarization resistance and corrosion rate. Potentiodynamic Polarization diagrams was performed to appreciate the passive domain. Ni-Cr Ugirex alloy show a better corrosion resistance in Ringer solution which will be reflected in a longer life of the dental structures made with this alloy as compared to the Ni-Cr Ducinox alloy, which will result in dental structures with a shorter lifespan. The electrochemical studies has shown that the alloy have a corrosion behavior similar to a passivating alloy, displaying an extensive passivity area due to formation of an oxide film.

Titanium (Ti) alloys used for narrow dental implants usually contain aluminum (Al) and vanadium (V) for improved resistance. However, those elements are linked to possible cytotoxic effects. Thus, this study evaluated the biomechanical behavior of narrow dental implants made with Al- and V-free Ti alloys by the finite element method. A virtual model of a partially edentulous maxilla received single implants (diameter: 2.7 and 2.9 mm; length: 10 mm) at the upper lateral incisor area, with respective abutments and porcelain-fused-to-metal crowns. Simulations were performed for each implant diameter and the following eight alloys (and elastic moduli): (1) Ti–6Al–4V (control; 110 GPa), (2) Ti–35Nb–5Sn–6Mo–3Zr (85 GPa), (3) Ti–13Nb–13Zr (77 GPa), (4) Ti–15Zr (113 GPa), (5) Ti–8Fe–5Ta (120 GPa), (6) Ti–26.88Fe–4Ta (175 GPa), (7) TNTZ–2Fe–0.4O (107 GPa), and (8) TNTZ–2Fe–0.7O (109 GPa). The implants received a labially directed total static load of 100 N at a 45° angle relative to their long axis. Parameters for analysis included the maximum and minimum principal stresses for bone, and von Mises equivalent stress for implants and abutments. Ti–26.88Fe–4Ta reaches the lowest maximum (57 MPa) and minimum (125 MPa) principal stress values, whereas Ti–35Nb–5Sn–6Mo–3Zr (183 MPa) and Ti–13Nb–13Zr (191 MPa) models result in the highest principal stresses (the 2.7 mm model surpasses the threshold for bone overload). Implant diameters affect von Mises stresses more than the constituent alloys. It can be concluded that the narrow implants made of the Ti–26.88Fe–4Ta alloy have the most favorable biomechanical behavior, mostly by mitigating stress on peri-implant bone. [ABSTRACT FROM AUTHOR]

The performance of the field and the condition of success in oral implantology today require the review and reevaluation of the means that contribute essentially to ensuring the stability and durability of the implant, starting from the nature of the biomaterial and continuing with the characteristics of the optimally designed biosurface. This paper proposes a comparative analysis of three commercial alloys, VeraBond, Kera N, and VeraSoft, compared to a modified dental alloy, with the aim of improving some mechanical properties. They have been studied structurally and mechanically. The microstructural structure shows that the alloys crystallize in the face-centered cube system, and the cast alloy has a dendritic structure with large grains. XRD diffractograms highlight that alloys exhibit three compounds Cr156.00 Al596.00: 9013031, Ni4.00, and Cr30.00Al48.00. The hardness measurements showed values between 203 HV and 430 HV. As the percentage of silicon increases, the hardness decreases. The modulus of elasticity obtained by the indentation method for the dental alloys was in the range of 46–153 GPa. The results showed that the hardness and elastic modulus of the new alloy was significantly minimized compared to the classical alloys used. [ABSTRACT FROM AUTHOR]

Introduction: Variation in the thickness of commercially available preformed rectangular archwires at the bracket positions has not been thoroughly studied. Therefore, this study measured the edgewise (height) and flatwise (width) dimensions of preformed rectangular nickel-titanium (NiTi) archwires at bracket positions corresponding to the central incisor, canine, and first molar and compared them among bracket positions., Methods: Sixty types of preformed rectangular NiTi mandibular archwires indicated as 0.019 × 0.025-in were obtained from 14 manufacturers. The height and width dimensions of archwires were measured at 4 points (3 bracket positions corresponding to the central incisor, canine, and first molar, and 1 terminal end) of each side of each archwire using a micrometer and compared with the indicated dimensions using 1-sample t tests. Furthermore, the measured dimensions were compared among the 3 bracket positions using a 1-way analysis of variance and Bonferroni post-hoc test., Results: The measured dimensions were significantly smaller than the indicated dimensions for all points except the central incisor point for height and significantly smaller than the indicated dimensions for all points for width. Comparisons among points showed that for height, the central incisor point was significantly larger than the first molar and terminal points. However, no significant differences were found for width at any point., Conclusions: The measured dimensions of preformed NiTi archwires at the bracket positions were generally smaller than the indicated dimensions, with variations observed not only among products but also among manufacturers., (Copyright © 2024 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Peri-implantitis occurs around dental implants, and implantoplasty has been used to address this ongoing disease; however, the changes to the physical properties of an implant after implantoplasty have not been well documented., Purpose: The purpose of this in vitro study was to determine the effect of implantoplasty on fracture strength and the load required for plastic deformation after cyclic fatigue on dental implants., Material and Methods: Twenty-six titanium/zirconium (TiZr) alloy implants (Roxolid Bone Level Implant; 4.1×10 mm) were embedded with 50% thread exposure and divided into 4 groups based on whether they had implantoplasty treatment by using different diamond rotary instruments and/or cyclic loading at 250 N for 2 million cycles: C0 (control, no cyclic loading), T0 (test, no cyclic loading), CM (control, cyclic loading), and TM (test, cyclic loading). After implantoplasty and/or cyclic loading, all implants underwent a load-to-failure test. The maximum fracture strength (FS) and load required for the onset of plastic deformation (PD) were recorded in Newtons. One-way ANOVA and nonparametric comparisons with control by using the Dunn and Wilcoxon method for joint ranking were used for statistical analysis., Results: The mean ±standard deviation FS for C0, CM, T0, and TM was 1465.2 ±86.4 N, 1480.7 ±64.1 N, 1299.3 ±123.8 N, and 1252.1 ±85.7 N, respectively. The mean ±standard deviation load for onset of PD for C0, CM, T0, and TM was 860.2 ±88.1 N, 797.0 ±130.5 N, 776.5 ±181.8 N, and 631.3 ±84.5 N, respectively. The TM group had a significantly lower FS and PD than the C0, CM, and T0 groups (P<.05) CONCLUSIONS: Both fracture strength (FS) and the onset of plastic deformation (PD) were significantly reduced after a TiZr alloy implant received implantoplasty and cyclic loading., (Copyright © 2022 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate magnetic susceptibility artefacts produced by orthodontic wires on MRI and the influence of wire properties and MRI image sequences on the magnitude of the artefact., Methods: Arch form orthodontic wires [four stainless steels (SS), one cobalt chromium (CC) alloy, 13 titanium (Ti) alloys] were embedded in a polyester phantom, and scanned using a 1.5-T superconducting magnet scanner with an eight-channel phased-array coil. All wires were scanned with T1-weighted spin echo (SE) and gradient echo (GRE) sequences according to the American Society for Testing and Materials (ASTM) F2119-07 standard. The phantom also scanned other eight sequences. Artefacts were measured using the ASTM F2119-07 definition and OsiriX software. Artefact volume was analysed according to metal composition, wire length, number of wires, wire thickness, and imaging sequence as factors., Results: With SE/GRE, black/white artefacts volumes from all SS wires were significantly larger than those produced by CC and Ti wires (P < .01). With the GRE, the black artefacts volume was the highest with the SS wires. With the SE, the black artefacts volume was small, whereas white artefacts were noticeable. The cranio-caudal extent of the artefacts was significantly longer with SS wires (P < .01). Although a direct relationship of wire length, number of wires, and wire thickness with artefact volume was noted, these factors did not influence artefact extension in the cranio-caudal direction., Conclusions: Ferromagnetic/paramagnetic orthodontic wires create artefacts due to local alteration of magnetic field homogeneity. The SS-type wires produced the largest artefacts followed by CC and Ti., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Institute of Radiology and the International Association of Dentomaxillofacial Radiology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aim of the study: the study on the allergic, inflammatory and toxic reactions of the dental alloys. Material and method: Oral clinical examination followed the presence of reactions due to some release elements in the oral environment. Morphopathological examination allowed to assess the reactivity of oral tissues who were in direct contact with dental materials. Results: the subjective symptoms incriminated was: metallic taste, burning sensations, decrease in taste sensitivity, etc. association with general status. Objective symptoms was: allergic, inflammatory, and chimico-toxic mechano-iritative reactions. Mophopatologic examen show atrophic aspects of oral mucosa with decrease dimension and papiles brides, or hipertrophic aspect, with inflammatory infiltration in the corion and distrophic lesions with to break off epithelium integrity. Conclusions: metallic restorations may determine unfavorable interactions between alloys and oral adjacent structures with severe clinical implications.

Background. CAD/CAM technologies facilitate using powder CoCr alloys to produce metal-ceramic dental restorations. However, base alloys may induce oxidative stress in the oral cavity due to corrosion and ion release. This study evaluated resistance to corrosion and release of metal ions from 3D printed CoCr dental alloy and their effect on oral oxidative stress. Methods. Metal-ceramic crowns with 3D printed copings from CoCr alloy EOS CobaltChrome SP2 (EOS, Germany) were fabricated for 35 patients. Inductively coupled plasma mass spectrometry (ICP-MS) was used for measuring the concentration of Co and Cr ions in non-stimulated saliva before prosthetic treatment (BPT), at 2 h and 7 days after the dental treatment (APT2, APT7, respectively). Open circuit potentials (Eocp) were evaluated at APT2 and APT7. Estimating oral oxidative stress, measurements of 8-isoprostaglandin F2-alpha were conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS) at stages BPT, APT2, and APT7. Results. Salivary Co level increased at APT2 and decreased to the initial levels at APT7. No statistical difference was found between the levels of 8-isoPGF2-alpha measured, and between the Eocp measurements at APT2 and APT7. Conclusions. The studied alloy showed stable corrosion resistance and the metal ion release did not induce oral oxidative stress.

Prosthetic rehabilitation of the maxillary front teeth is an extremely laborious problem for the dental team, consisting of the dentist and the dental technician. If for the physiognomic component the most recommended materials are the ceramic masses, for the resistance substrate there are several variants. Conventional technologies using dental alloys and modern ones involving the use of zirconium dioxide can be used successfully in performing fixed prosthetic restorations in the maxillary frontal area, both options having both advantages and disadvantages, as we will describe in this material. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was the microscopy evaluation of the outer prosthetic surfaces in the case of four restorative dental materials: two metal alloys, one noble and one non-noble, and two dental ceramics, one based on lithium disilicate, the other based on zirconia. The samples were made as anatomical crowns in dental laboratory using the specific protocol for each analysed material. The general appearance of the occlusal and buccal surfaces is shown at several magnifications and the results are discussed in relation to the data from the literature and their clinical importance. Among the metallic materials, the noble alloys offered more homogeneous images with smaller cavities, while the final layer of glaze offer a glossier surface for the ceramics materials, in which other small particles may be incorporated, depending on the analysed ceramics . The use of an optical microscope for the final evaluation of the prosthetic structure may bring important details leading to an improvement of the obtained prosthetic structures.

Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p

The aim of this paper was to study the corrosion behavior of Nickel - Base - Dental Alloys in Ringer biological fluid. The Nickel base alloys are widely used for medical purposes, especially for prosthetic works in the field of dentistry. The applied electrochemical methods used for corrosion investigations are Open Circuit Potential, Linear Polarization during time of immersion in order to calculate the polarization resistance and corrosion rate. Potentiodynamic Polarization diagrams was performed to appreciate the passive domain. Ni-Cr Ugirex alloy show a better corrosion resistance in Ringer solution which will be reflected in a longer life of the dental structures made with this alloy as compared to the Ni-Cr Ducinox alloy, which will result in dental structures with a shorter lifespan. The electrochemical studies has shown that the alloy have a corrosion behavior similar to a passivating alloy, displaying an extensive passivity area due to formation of an oxide film. [ABSTRACT FROM AUTHOR]

Objective: To compare the amount of mercury in new and old dental amalgam restorations. Material and Methods: This study analyzed twenty samples of dental amalgam restorations, dividing into two groups. Group 1 consisted of samples of new dental amalgam restoration (n=10) and group 2 consisted of samples of old dental amalgam restoration (5-years old) (n=10). In each group, the mercury involved in the dental amalgam restoration was calculated using the cloud point extraction (CPE) method. The new dental amalgam restorations are taken from the patients' mouth after condensation and analyzed directly after setting. The old dental amalgam restorations are removed from the patients' mouth, after 5 years of use by the patients, and then they are analyzed. The independent-samples t-test was used to analyze the differences (p

Objective: To evaluate the difference in torsional resistance, angular deflection and fragment length between two new rotary instruments: AF Blue S4 and S-One. These files share all features except cross- sectional design. Material and Methods: A total of 40 new Nickel-Titanium instruments of 25 mm in length were tested in this study and divided in two groups: 20 AF Blue S4, tip 25 and constant 6% taper and 20 AF-Blue S4 tip 25 and constant 6% taper. The torsional test was performed by the use of a torque recording endodontic motor (KaVo, Biberac, Germany). Torque to Fracture (TtF), Angular Deflection (AD) and Fragment Length (FL) was recorded for each instrument. To ensure an immovable block at 3mm of the instrument tip, an auto-polymerizing resin (DuraLay; Reliance Dental Mfg Co, Worth, IL) was used. Each file was rotated clockwise at a speed of 300 rpm until fracture occurred. Results: Group A (AF Blue S4) showed higher TtF and AD than Group B (S-One), and statistical analysis found significant differences between the two instruments (p0.05) between the two instruments. Conclusion: The AF Blue S4 seems to have a higher resistance to torsional stress in vitro. Clinically, the use of AF Blue S4 could be safer in narrow canals.

Objective: This in vitro study aimed to evaluate the torque expression efficiency when it is integrated into the bracket slot versus the bracket base. Additionally, the impact of archwire geometry (rectangular vs. rhomboid) on torque expression has been examined., Material and Methods: The torque expression was evaluated in a full arch printed maxillary model, focusing on tooth #11, which was positioned within an alveolus filled with Typodont wax. Three different types of brackets were utilized: conventional metallic bracket (Minidiamond™), self-ligating bracket with torque in base (Damon Q2™), and a new self-ligating bracket design with torque in slot (Damon Ultima™). Two variations of archwires were used: rectangular and rhomboid stainless steel, measuring 0.019×0.025 inches and 0.019×0.0275 inches, respectively, from ORMCO™. The study included seven groups: six experimental groups and a control group, with 15 measurements in each group, totaling 105 torque measurements. Optical impressions were taken of the tooth's original position and its final position after torque expression. STL files were superimposed using GEOMAGIC software to calculate the percentage of torque expression., Results: The self-ligating bracket with torque in slot (Damon Ultima™) shows significantly higher torque expression than the self-ligating bracket with torque in base (Damon Q2™) with a rectangular stainless steel archwire (P=0.00015). The Ultima™ bracket also demonstrates higher torque expression than both the Q2™ and conventional 22° brackets with a rhomboid stainless steel archwire (P<0.003). No significant difference in torque expression was found between the rectangular and rhomboid stainless steel archwires for any bracket group (P>0.05)., Conclusions: The self-ligating bracket with torque in slot shows comparable torque expression effectiveness to the conventional bracket, outperforming the self-ligating bracket with torque in base. Archwire geometry does not significantly impact torque expression., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

IntroductionThe purpose of this study was to evaluate the effect of 2 different temperatures (20°C and 37°C) on the cyclic fatigue life of rotary instruments and correlate the results with martensitic transformation temperatures.MethodsContemporary nickel-titanium rotary instruments (n = 20 each and tip size #25, including Hyflex CM [Coltene, Cuyahoga Falls, OH], TRUShape [Dentsply Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [Dentsply Tulsa Dental Specialties], and ProTaper Universal [Dentsply Tulsa Dental Specialties]) were tested for cyclic fatigue at room temperature (20°C ± 1°C) and at body temperature (37°C ± 1°C). Instruments were rotated until fracture occurred in a simulated canal with an angle curvature of about 60° and a radius curvature of 3 mm; the center of the curvature was 4.5 mm from the instrument tip. The number of cycles to fracture was measured. Phase transformation temperatures for 2 instruments of each brand were analyzed by differential scanning calorimetry. Data were analyzed using the t test and 1-way analysis of variance with the significance level set at 0.05.ResultsFor the tested size and at 20°C, Hyflex CM showed the highest resistance to fracture; no significant difference was found between TRUShape and Vortex Blue, whereas ProTaper Universal showed the lowest resistance to fracture. At 37°C, resistance to fatigue fracture was significantly reduced, up to 85%, for the tested instruments (P

Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files. [ABSTRACT FROM AUTHOR]

Objective The aims of this in vitro study were to assess if dynamic loading increases the metal ion release of selected dental alloys and to evaluate the cytotoxicity of the released metal ions. Materials and methods One Pd–Ag alloy (Aurolite 2B) and two Co–Cr alloys (Wirobond 280 and d.Sign 30) were investigated. Two different corrosion immersion tests were used: a standardized static test (ISO 22674: 2016) and an experimental dynamic test. Both tests involved immersion of the specimens in a lactic acidic solution (pH = 2.3). Inductively coupled plasma mass spectrometry was used to identify and quantify released elements. A human monocyte cell-line (THP-1) was exposed to serially diluted solutions containing the selected metal ions. Cell viability was measured using the methyl-thiazolyl-tetrazolium assay. Results According to the threshold defined in ISO 22674, only low concentrations of released elements were observed for both corrosion tests. No increase in metal ion release from the dynamic test compared with the static test was observed. Of the released elements, only Zn(II) and Co(II) showed a cytotoxic effect on THP-1 cells at 250 µM and higher concentrations. No increased viability loss was observed when adding other released elements to the exposure mixture. Conclusions The tested alloys showed low levels of metal ion release from both static and dynamic corrosion testing. Dynamic loading did not increase the metal ion release compared to the static corrosion test. Concentrations of 250 µM and above of Zn(II) and Co(II) showed a cytotoxic effect on THP-1 cells.

Abstract Dental alloys are widely used in fabrication of removable partial dentures, particularly as a dental framework. The present study aimed at studying the effect of the commercial mouthwashes on the corrosion behavior of the Co−Cr dental casting alloy. Corrosion behavior was investigated in alcohol-free and alcohol-containing mouthwashes added to artificial saliva solutions at room temperature by electrochemical tests recorded the open circuit potential (OCP) and current density, after the surface analysis of the samples was performed. During the early 250s, the OCP values showed significant changes, with the exception of one test group containing alcohol, where potential decreased continuously during the test, which also recorded the highest current density, different from the other groups. It was observed that the presence of alcohol increased the current density and the corrosion process in this alloy and the mouthwashes had more aggressive action in specimens submitted to solutions with alcohol in the composition.

Background: Piezocision is a minimally invasive surgical method aiming to accelerate tooth movement. However, its effect was found to be transient, appertaining to the regional acceleratory phenomenon (RAP). Hence, the aim of the study was to evaluate the effect of single and multiple piezocisions on the rate of orthodontic tooth movement (OTM). Moreover, the impact of both protocols on canine tipping and orthodontically induced inflammatory root resorption (OIIRR) has been assessed., Methods: Thirty indicated patients for the therapeutic extraction of maxillary first premolars were enlisted in this split-mouth study, and they were randomly split into two equal groups, each including 15 subjects. In the Single Application Group (SAG), one side of the maxillary arch arbitrarily received a single piezocision before the onset of canine retraction, whereas in the Multiple Application Group (MAG), piezocisions were randomly performed on one side, three times on a monthly basis, over the 12-week study period. The contralateral sides of both groups served as the controls. Canine retraction was carried out bilaterally using nickel-titanium closed-coil springs, delivering 150 g of force, and the rate of tooth movement, as well as canine tipping were evaluated on a monthly basis, over a 3-month period. Cone-bean computed tomography scans were also conducted pre- and post- canine retraction, and OIIRR was assessed using Malmgren Index., Results: The reported outcomes revealed a significant increase in the amount of canine retraction, canine tipping, as well as root resorption scores on the experimental sides in both groups SAG and MAG post-retraction (p < 0.001). However, upon comparing the experimental sides in both groups, non-significant differences have been observed between them regarding all the assessed outcomes (p > 0.05)., Conclusions: Single and multiple piezocisions effectively accelerate OTM in comparison to conventional orthodontic treatment, with relative outcomes reported by both intervention frequencies. Accordingly, single piezocision is recommended as an adjunct to OTM. Furthermore, significant tooth tipping as well as a significantly higher root resorption risk accompanies both single and multiple piezocision applications in conjunction with OTM., Name of the Registry: Clinicaltrials.gov TRIAL REGISTRATION NUMBER: NCT05782088 DATE OF REGISTRATION: 23/03/2023 "Retrospectively registered". URL: https://clinicaltrials.gov/ct2/show/NCT05782088., (© 2024. The Author(s).)

Orthodontic uprighting or traction of an impacted mandibular second molar often necessitates invasive interventions. This report aims to illustrate the utilization of nickel-titanium wire segments inserted into small, simple tubes for uprighting mesially impacted mandibular second molars and also for scissor bite correction. The term "simple tube" refers to a tube without a bonding base attached to a tooth surface by covering it with flowable composite resin. Due to the absence of a bonding base, the simple tube is characterized by its diminutive size and minimal profile height, facilitating placement on partially exposed second molars and unconventional positioning to adjust the force geometry. In this case study, mesially-impacted mandibular second molars with scissor bite were uprighted in a 21-year-old male utilizing simple tubes. Simple tubes can be used for molar uprighting and scissor bite correction buccally and lingually., (Copyright © 2024. Published by Elsevier Inc.)

Objectives: To address the quality problems caused by high porosity in the preparation of dental cobalt-chrome alloy prosthetics based on selective laser melting (SLM) technology, we investigated the influence mechanism of different forming process parameters on the microstructure and properties of the materials. Moreover, the range of forming process parameters that can effectively reduce defects was precisely defined., Methods: The effects of laser power, scanning speed, and scanning distance on the pore properties, surface roughness, and hardness of dental cobalt-chrome alloy were investigated by adjusting the printing parameters in the process of SLM. Through metallographic analysis, image analysis, and molten pool simulation, the pore formation mechanism was revealed, and the relationship between the porosity and energy density of SLM dental cobalt-chrome alloy was elucidated., Results: When the linear energy density was higher than 0.18 J/mm, the porosity defect easily appeared at the bottom of the molten pool. When the laser energy density was lower than 0.13 J/mm, defects occurred in the gap of the molten pool due to insufficient melting of powder. In particular, when the linear energy density exceeded the threshold of 0.30 J/mm or was below 0.12 J/mm, the porosity increased significantly to more than 1%. In addition, we observed a negative correlation between free surface roughness and energy density and an inverse relationship between macroscopic hardness and porosity., Conclusions: On the basis of the conditions of raw materials and molding equipment used in this study, the key process parameters of SLM of molding parts with porosity lower than 1% were successfully determined. Specifically, these key parameters included the line energy density, which ranged from 0.13 J/mm to 0.30 J/mm, and the scan spacing should be strictly controlled below 90 μm.

The performance of the field and the condition of success in oral implantology today require the review and reevaluation of the means that contribute essentially to ensuring the stability and durability of the implant, starting from the nature of the biomaterial and continuing with the characteristics of the optimally designed biosurface. This paper proposes a comparative analysis of three commercial alloys, VeraBond, Kera N, and VeraSoft, compared to a modified dental alloy, with the aim of improving some mechanical properties. They have been studied structurally and mechanically. The microstructural structure shows that the alloys crystallize in the face-centered cube system, and the cast alloy has a dendritic structure with large grains. XRD diffractograms highlight that alloys exhibit three compounds Cr156.00 Al596.00: 9013031, Ni4.00, and Cr30.00Al48.00. The hardness measurements showed values between 203 HV and 430 HV. As the percentage of silicon increases, the hardness decreases. The modulus of elasticity obtained by the indentation method for the dental alloys was in the range of 46–153 GPa. The results showed that the hardness and elastic modulus of the new alloy was significantly minimized compared to the classical alloys used.