RESUMO
OBJECTIVE: This study aimed to compare the insertion torque (IT), flexural strength (FS) and surface alterations between stainless steel (SS-MIs) and titanium alloy (Ti-MIs) orthodontic mini-implants. METHODS: Twenty-four MIs (2 x 10 mm; SS-MIs, n = 12; Ti-MIs, n = 12) were inserted on artificial bone blocks of 20 lb/ft3 (20 PCF) and 40 lb/ft3 (40 PCF) density. The maximum IT was recorded using a digital torque meter. FS was evaluated at 2, 3 and 4 mm-deflection. Surface topography and chemical composition of MIs were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). General linear and mixed models were used to assess the effect of the MI type, bone density and deflection on the evaluated outcomes. RESULTS: The IT of Ti-MIs was 1.1 Ncm greater than that obtained for the SS-MIs (p= 0.018). The IT for MIs inserted in 40 PCF test blocks was 5.4 Ncm greater than that for those inserted in 20 PCF test blocks (p < 0.001). SS-MIs inserted in higher density bone (40 PCF) had significantly higher flexural strength than the other groups, at 2 mm (98.7 ± 5.1 Ncm), 3 mm (112.0 ± 3.9 Ncm) and 4 mm (120.0 ± 3.4 Ncm) of deflection (p< 0.001). SEM evidenced fractures in the Ti-MIs. EDS revealed incorporation of 18% of C and 2.06% of O in the loaded SS-MIs, and 3.91% of C in the loaded Ti-MIs. CONCLUSIONS: Based on the findings of this in vitro study, it seems that SS-MIs offer sufficient stability and exhibit greater mechanical strength, compared to Ti-MIs when inserted into higher density bone.
Assuntos
Ligas Dentárias , Implantes Dentários , Resistência à Flexão , Teste de Materiais , Microscopia Eletrônica de Varredura , Procedimentos de Ancoragem Ortodôntica , Aço Inoxidável , Propriedades de Superfície , Titânio , Torque , Titânio/química , Aço Inoxidável/química , Procedimentos de Ancoragem Ortodôntica/instrumentação , Procedimentos de Ancoragem Ortodôntica/métodos , Ligas Dentárias/química , Técnicas In Vitro , Espectrometria por Raios X , Análise do Estresse Dentário , Humanos , Estresse Mecânico , Densidade ÓsseaRESUMO
INTRODUCTION: The aim of this study was to assess the interaction between a 0.019×0.025-inch (â³) stainless steel archwire and two types of passive self-ligating brackets with the same slot height (0.022â³) and different slot depths (0.028â³ and 0.026â³, and to measure the archwire/slot play as well as to compare the torque expression with archwire torsions of 12°, 24°, and 36°. MATERIAL AND METHODS: An experimental device was developed along with a universal testing machine to measure torque expression in two types of brackets with 0.028â³ and 0.026â³ slot depths. Analysis of variance (ANOVA) and Tukey's test were performed to identify the differences between groups. RESULTS: The 0.026â³ slot bracket presented greater archwire/slot play when compared to the 0.028â³ bracket. Torque expression with torsions of 24° and 36° were significantly higher in the 0.028â³ depth brackets when compared to the 0.026â³ depth brackets. CONCLUSION: The 0.022â³×0.026â³ passive self-ligating brackets attached with a 0.019â³×0.025â³ stainless steel archwire provided no greater torque control when compared to 0.022â³×0.028â³ passive self-ligating brackets.
Assuntos
Análise do Estresse Dentário , Teste de Materiais , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Fios Ortodônticos , Aço Inoxidável , Torque , Humanos , Ligas Dentárias/química , Técnicas In Vitro , Torção MecânicaRESUMO
INTRODUCTION: This study aimed to investigate the surface free energy and surface roughness (SR) of metallic alloys under the influence of acid solutions. METHODS: The experiment involved the use of 270 rectangular wire samples measuring 0.019 × 0.025-in. These samples were sourced from 3 different commercial brands: Dentsply GAC, American Orthodontics, and Orthoclassic. This in vitro study categorized the samples into 3 groups based on the solutions employed: deionized water, citric acid, and phosphoric acid. Each group consisted of 90 samples, with 30 samples representing each type of alloy-stainless steel, nickel-titanium, and titanium molybdenum alloy (TMA). The wire segments were immersed in their respective solutions for 72 hours at a controlled temperature of 37°C, with continuous orbital agitation at 130 rpm. After the immersion period, the study analyzed both surface free energy and SR. The mean values obtained were subjected to an analysis of variance at a significance level of 5%. RESULTS: All alloys displayed hydrophobic behavior, as indicated by interaction free energy values <0. In acidic environments (phosphoric acid and citric acid), significant differences were observed among different brands and alloys, affecting surface energy and interaction free energy. Variations in SR among metallic alloys included steel with the lowest SR variations, followed by nickel-titanium and TMA. Notably, the TMA alloy stood out with significantly higher surface energy compared with that of the other alloys (P <0.001). CONCLUSIONS: In this study, all examined alloys demonstrated a hydrophobic nature, suggesting a limited attraction to water. Notably, TMA exhibited the least hydrophobic behavior among the alloys studied. However, when exposed to citric acid, TMA displayed the most substantial alterations in its surface properties. These results underscored the significance of accounting for the distinctive properties of each alloy and their responses to diverse challenges, such as exposure to acidic solutions, during the selection of orthodontic wires for orthodontics treatment.
Assuntos
Ligas , Ligas Dentárias , Teste de Materiais , Fios Ortodônticos , Propriedades de Superfície , Corrosão , Ligas Dentárias/química , Níquel/química , Titânio/química , Ácido Cítrico/química , Aço Inoxidável/química , Ácidos Fosfóricos/química , Molibdênio/químicaRESUMO
AIM: This study aimed to compare three rotary instruments produced by the EDM process with the heat-treated ProTaper Gold system regarding design, metallurgy, mechanical properties and shaping ability. METHODOLOGY: HyFlex EDM (25/~), Neoniti (25/.06), EDMax (25/.06) and ProTaper Gold (25/.08v) instruments (n = 58 per group) were compared regarding design, metallurgy and mechanical performance. Unprepared canal areas were calculated for each system after preparation of mesiobuccal, mesiolingual and distal canals of mandibular molars (15 canals per group) using micro-CT technology. Statistical analyses were performed using One-way anova post-hoc Tukey and Kruskal-Wallis post-hoc Dunn's tests (α = 5%). RESULTS: All instruments had asymmetrical blades, no radial lands, no major defects and almost equiatomic nickel/titanium ratios, but different cross-section designs, tip geometries and surface appearances. Although instruments had distinct transformation temperature curves, they showed crystallographic martensitic arrangement at 21°C and mixed austenite plus R-phase at body temperature. Neoniti and HyFlex EDM showed similar results in all mechanical tests (p > .05), while EDMax and ProTaper Gold had similar time to fracture (p = .841), maximum bending load (p = .729), and cutting ability (p = .985). ProTaper Gold showed the highest torque to failure (p < .001) and HyFlex EDM had the lowest buckling resistance (p < .001). Mean percentages of unprepared canal areas ranged from 20.4% to 25.7% in the mesial canals, and from 20.8% to 26.2% in the distal canal, with no statistical differences among systems (p > .05). CONCLUSIONS: Instruments' geometry and phase transformation temperatures influenced the results of the mechanical tests, but not their shaping ability.
Assuntos
Preparo de Canal Radicular , Humanos , Ligas Dentárias/química , Instrumentos Odontológicos , Desenho de Equipamento , Teste de Materiais , Temperatura , Titânio/química , TorqueRESUMO
OBJECTIVE: The aim of this study was to evaluate the force degradation and deformation over time of an open-closed and open coil spring. MATERIAL AND METHODS: 40 NiTi springs were divided into 2 groups according to the manufacturer (20 specimens per group): Morelli™ (Sorocaba, SP, Brazil) and Orthopli™ (Philadelphia, PA, USA). Then, they were subdivided into 2 groups according to the type of spring (n=10): open spring and open-closed spring. The springs were submitted to the initial compression test in a Universal Test Machine (Instron) in 43.3% of the initial length and analyzed in 3 points (0.5mm, 3.25mm and 6.5mm). After this, the springs were activated with a 240 gf and those maintained for 4 weeks in artificial saliva in the oven at 37°C, and analyzed by a new compression test with the same initial parameters. Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) analyzed the spring's morphology. Two-way repeated measures Analysis of Variance was applied for each brand and extension of compression. Student t-test with correction of Bonferroni was used to compare open spring vs open-closed springs and pairwise t-test was used to compare initial vs final period. The level of significance was set at 95% in all tests. The most representative images were selected (SEM/EDS). RESULTS: The Orthopli™ open-closed spring showed a statistically higher deformation (14.52±0.37) in relation to open spring (14.85±0.19) after 4 weeks (P<0.05). No statistical difference was observed between the types of Morelli™ springs (P>0.05). Orthopli™ open-closed spring showed force values statistically higher than the open spring in the initial and final time (P<0.05). Regardless of the type of spring, the initial force was significantly higher than the final force (P<0.05). CONCLUSIONS: The orthodontist should not rely on the indicated force range without considering the type of spring (open or open-closed), the manufacturer and the amount of compression of the spring.
Assuntos
Ligas Dentárias/química , Análise do Estresse Dentário/instrumentação , Fios Ortodônticos , Ortodontia , Análise de Variância , Elasticidade , Humanos , Teste de Materiais/instrumentação , Fenômenos Mecânicos , Níquel , Projetos Piloto , TitânioRESUMO
This study was undertaken to assess in vivo the corrosion in two commercial nickel-titanium (NiTi) orthodontic archwires removed from the oral cavity of patients using fluoride mouthwashes. Five volunteers took part in this study on the corrosion behavior of two brands of NiTi archwires (3M and AO (brand of archwire)) during use of two mouthwashes with neutral sodium fluoride 1.1%, one with acidulated fluoride 1.1%, and one with placebo and a control group. Each patient used one mouthwash in three different periods of time for 1 min a day for 30 days. The archwires were assessed with scanning electron microscopy and atomic force microscopy for qualitative and quantitative analysis. The values obtained with atomic force microscopy (AFM) were submitted to normality test, two-way analysis of variance, and Tukey's test at a significance level of 5%. The AFM images showed a gradual qualitative increase in the roughness of both types of wire between the treatments: control < placebo < neutral fluoride < acidulated fluoride. The arithmetic average of the roughness and root mean square of the roughness were similar. As for 3M archwires, only the acidulated fluoride group differed statistically from the others. As for AO archwires, the control and placebo groups did not differ from each other, but differed from the other fluoride treatments. The group using neutral fluoride also differed significantly from the acidulated fluoride group. 3M archwires were not affected by daily oral challenges. AO archwires were not affected by daily oral challenges either; their association with fluoride, either neutral or acidulated, increased their roughness.
Assuntos
Ligas Dentárias/química , Níquel/química , Fios Ortodônticos , Estresse Fisiológico/fisiologia , Propriedades de Superfície , Titânio/química , Adolescente , Adulto , Corrosão , Cárie Dentária/patologia , Feminino , Humanos , Masculino , Teste de Materiais , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Antissépticos Bucais/química , Antissépticos Bucais/farmacologia , Fluoreto de Sódio/química , Fluoreto de Sódio/farmacologia , Desmineralização do Dente/patologia , Adulto JovemRESUMO
Abstract 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<0.05). Results: For new amalgam restorations, the mean of mercury was 0.1281 µg/mL, while for old restorations it was 0.1029 µg/mL. There was a significant difference between the new and old amalgam restorations in the amount of mercury available (p<0.001). Conclusion: There is a significant loss of mercury over a five years period in the patient mouth.
Assuntos
Humanos , Ligas Dentárias/química , Amálgama Dentário , Materiais Dentários , Mercúrio , IraqueRESUMO
To evaluate the torsional properties of engine-driven pathfinding instruments manufactured from different NiTi alloys - R-Pilot (tip size 12.5;.04 taper; M-Wire) and One G (tip size 14;.03 taper; Conventional NiTi). A total of 40 NiTi instruments from engine-driven pathfinding instruments (n = 20) were used. The torsion tests followed ISO 3630-1 (1992). Three millimeters of each instrument tip was fastened to a small load cell by a lever arm linked to the axis of torsion. During the test, the torsion testing machine software measured the maximum torsional strength and angle of rotation (0) before instrument failure. The fractured surface of each instrument was assessed by scanning electron microscopy (SEM). In addition, a supplementary examination was performed to measure the cross-sectional area and the metal mass volume of each instrument 3 mm from the tip. Data were analyzed using a t-test, with significance level set at 5%. R-pilot had significantly higher torsional strength than did One G (p < 0.05). Regarding the angle of rotation to fracture, One G had higher angles than did R-Pilot (p < 0.05). The supplementary examination showed that R-Pilot had the highest cross-sectional area and volume of metal mass at 3 mm from the tip (p < 0.05). R-pilot (M-Wire NiTi alloy) had a significantly higher torsional strength and One-G (superelastic NiTi alloy) had the highest angle of rotation to fracture.
Assuntos
Ligas/química , Ligas Dentárias/química , Instrumentos Odontológicos , Preparo de Canal Radicular/instrumentação , Análise de Variância , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Estresse Mecânico , Propriedades de Superfície , TorqueRESUMO
BACKGROUND: Titanium (Ti) and its alloys possess high biocompatibility and corrosion resistance due to Ti ability to form a passive oxide film, i.e. TiO2, immediately after contact with oxygen. This passive layer is considered stable during function in the oral cavity, however, emerging information associate inflammatory peri-implantitis to vast increases in Ti corrosion products around diseased implants as compared to healthy ones. Thus, it is imperative to identify which factors in the peri-implant micro-environment may reduce Ti corrosion resistance. METHODS: The aim of this work is to simulate peri-implant inflammatory conditions in vitro to determine which factors affect corrosion susceptibility of Ti-6Al-4V dental implants. The effects of hydrogen peroxide (surrogate for reactive oxygen species, ROS, found during inflammation), albumin (a protein typical of physiological fluids), deaeration (to simulate reduced pO2 conditions during inflammation), in an acidic environment (pH 3), which is typical of inflammation condition, were investigated. Corrosion resistance of Ti-6Al-4V clinically-relevant acid etched surfaces was investigated by electrochemical techniques: Open Circuit Potential; Electrochemical Impedance Spectroscopy; and Anodic Polarization. RESULTS: Electrochemical tests confirmed that most aggressive conditions to the Ti-6Al-4V alloy were those typical of occluded cells, i.e. oxidizing conditions (H2O2), in the presence of protein and deaeration of the physiological medium. CONCLUSIONS: Our results provide evidence that titanium's corrosion resistance can be reduced by intense inflammatory conditions. This observation indicates that the micro-environment to which the implant is exposed during peri-implant inflammation is highly aggressive and may lead to TiO2 passive layer attack. Further investigation of the effect of these aggressive conditions on titanium dissolution is warranted.
Assuntos
Ligas Dentárias/química , Implantes Dentários/normas , Teste de Materiais/métodos , Titânio/química , Ácidos/química , Ligas , Corrosão , Técnicas Eletroquímicas/métodos , Humanos , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Inflamação/induzido quimicamente , Inflamação/complicações , Microscopia Eletrônica de Varredura , Modelos Químicos , Propriedades de SuperfícieRESUMO
AIM: To evaluate artefact intensity in cone beam computed tomography (CBCT) images of two alloys used in metal posts scanned using different exposure parameters. METHODOLOGY: The sample consisted of 20 single-rooted teeth divided into two groups for use with either a NiCr post or AgPd post. All teeth were scanned with and without their corresponding metal posts and with and without the presence of an extra restored tooth in the arch. The samples were scanned using CS 9000 3D scanner with two exposure protocols: 85 kV 6.3 mA and 85 kV 10 mA. Voxel size and FOV were fixed at 0.100 mm and 5 cm × 3.75 cm. The presence of artefacts was assessed qualitatively by two calibrated observers using the CBCT volume and paired 2D images, and quantitatively by one trained observer, using ImageJ software. Wilcoxon's signed rank, Mann-Whitney, kappa and chi-square tests were used for qualitative analyses. Two-way anova and Tukey's tests were used for quantitative analyses. All analyses were conducted considering the 95% confidence level (α < 0.05). RESULTS: For the CBCT volume qualitative analysis, significant differences were observed between the metal alloys in the presence of an extra restored tooth, with higher artefact intensity for AgPd when assessing hypodense halos and lines (P = 0.006). Images with two restored teeth had significantly more hypodense and hyperdense lines (P = 0.033). When evaluating exposure parameters and number of restored teeth, the paired image quality analysis revealed significant disagreement between observers for diagnostic image quality (P = 0.001). Quantitative artefact analysis revealed higher artefact intensity for the AgPd posts in the presence of two restored teeth. CONCLUSION: Although the exposure parameters tested did not interfere with artefact intensity, post alloys with a higher atomic number and the presence of another metal structure in the arch increased artefact intensity and impaired the diagnostic quality of CBCT images.