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1.
Niger J Clin Pract ; 23(1): 41-45, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31929205

RESUMEN

Objective: This in vitro study aimed to compare the cyclic fatigue resistance of HyFlex EDM (HEDM), Vortex Blue (VB), ProTaper Gold (PG), and OneCurve (OC) nickel-titanium (NiTi) instruments. Materials and Methods: About 12 HEDM (25/.~), 12 VB (25/.06), 12 PG (25/.08), and 12°C (25/.06) instruments were included in this study. All the instruments were tested with a 60° angle of curvature and a 3-mm radius of curvature. All the instruments were utilized until fracture occurred, and then the number of cycles to failure (NCF) was calculated. The data were analyzed statistically using Kruskal-Wallis H and Mann-Whitney U-tests. The statistical significance level was set at P < 0.05. Results: HEDM instruments had the highest cyclic fatigue resistance among all the other instruments (P < 0.05). The OC instruments had a significantly higher fatigue resistance than the PG and VB instruments (P < 0.05); however, there was no significant difference between PG and VB instruments in the NCF (P > 0.05). Conclusion: Within the limitations of this in vitro study, it was found that the cyclic fatigue resistance was higher for the HEDM instruments than for the VB, PG, and OC instruments.


Asunto(s)
Aleaciones Dentales/química , Instrumentos Dentales , Falla de Equipo , Ensayo de Materiales , Preparación del Conducto Radicular/instrumentación , Aleaciones , Diseño de Equipo , Oro , Humanos , Níquel/química , Titanio/química
2.
Chemosphere ; 243: 125205, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31726262

RESUMEN

To determine whether the potential effects on liver and kidney caused by dental alloys could be reduced or terminated by the removal of nickel-chromium (Ni-Cr) alloy, cobalt-chromium (Co-Cr) alloy, and commercially pure titanium (CP-Ti), they were placed in the cheek pouches of Syrian hamsters according to ISO 10993-10. Then, the peak/plateau and end times of trace metals in the blood were determined with or without the removal of the dental alloys. Based on these time points, the trace metals and their effects on liver and kidney were examined. We found that trace metals released from these dental alloys and titanium were accumulated transiently in the blood, liver, and kidney but had no effect on the histopathology of the liver or kidney. Although the functions of the liver and kidney were compromised, the function of these tissues seemed to be clinically acceptable compared to those in control Syrian hamsters. In addition, the apoptotic effect on renal cells was terminated by removing the Ni-Cr and Co-Cr alloys, and that on hepatocytes was also eliminated by removing the Ni-Cr alloy. In contrast, the effect of the Co-Cr alloy on hepatocytes was temporary and recovered by itself. Taken together, Ni- and Co-based dental alloys and titanium have no effect on the histopathology or function of liver and kidney. Moreover, Ni-Cr and Co-Cr alloys induce transient trace metal accumulation and apoptotic effects in liver and kidney, which can be reduced or terminated by the removal of the alloys, while CP-Ti shows favorable biocompatibility.


Asunto(s)
Aleaciones de Cromo/química , Aleaciones Dentales/química , Titanio/química , Aleaciones , Aleaciones de Cromo/toxicidad , Aleaciones Dentales/toxicidad , Riñón , Hígado , Ensayo de Materiales , Titanio/toxicidad
3.
Artículo en Inglés | LILACS-Express | LILACS, BBO - Odontología | ID: biblio-1135560

RESUMEN

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.


Asunto(s)
Humanos , Aleaciones Dentales/química , Amalgama Dental , Materiales Dentales , Mercurio , Irak
4.
Biomed Res Int ; 2019: 6368958, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31828110

RESUMEN

Nickel-titanium (NiTi) rotary files have enabled efficient root canal preparations that maintain the canal center with fewer aberrations compared to hand files. However, NiTi rotary files are susceptible to fracture, which can thereby compromise root canal treatment. Therefore, NiTi files have been developed to enhance fracture resistance by modifying design and thermal treatment. The objective of this study was to compare the torsional fatigue resistance and bending resistance of NiTi files manufactured from different alloys and treatments. ProTaper NEXT X2 (PTN; M-wire), V taper 2H (V2H; controlled memory wire), NRT (heat-treated), and One Shape (OS; conventional alloy) instruments of tip size #25 were compared. Torsional fatigue was evaluated by embedding the 3 mm tip of each instrument (N = 10/brand) in resin and the repetitive application of torsional stress (300 rpm, 1.0 N·cm) by an endodontic motor with autostop when the file fractured. The number of loading cycles to fracture was recorded and analyzed by Kruskal-Wallis and Mann-Whitney U tests with Bonferroni's correction. Bending resistance of the instruments was tested using a cantilever bending test to the 3 mm point from the tip (N = 10/brand). The stress was measured when deflection of 3 mm was subjected and statistically analyzed with a one-way analysis of variance and Tukey's honest significance difference test (α = 0.05). V2H withstood the highest number of load applications during torsional fatigue testing (p < 0.05), followed by NRT, PTN, and OS, where the differences between NRT and PTN (p=0.035) and between PTN and OS (p=0.143) were not statistically significant. V2H showed the lowest bending stiffness, followed by NRT, PTN, and OS (p < 0.001). Thermal treatment of NiTi wire resulted in improved mechanical properties, and controlled memory wire provided improved flexibility and torsional fatigue resistance.


Asunto(s)
Aleaciones/química , Aleaciones Dentales/química , Ensayo de Materiales , Níquel/química , Estrés Mecánico , Titanio/química , Preparación del Conducto Radicular
5.
Clin Exp Dent Res ; 5(5): 452-459, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31687177

RESUMEN

Purpose: The purpose of this study was to investigate the corrosion resistance of galvanically coupled SLA and anodized implant surfaces with a Co-Cr alloy. Materials and Methods: Three groups were included in this study. The first (SLA) was composed of SLA implants (Institut Straumann, Basel, Switzerland), the second (ANO) of NobelReplace® (Nobel Biocare, Göteborg, Sweden), and the third (MIX) of both implant systems combined. All groups were assembled with a single Co-Cr superstructure. Electrochemical testing included open-circuit potential, electrochemical impedance spectroscopy, cyclic potentiodynamic polarization, and chronoamperometric current-time measurements. The quantitative results (EOCP, ECORR, ICORR, EPROT, RP, and ICA) were statistically analyzed by one-way ANOVA and Tukey's post-hoc multiple comparison test (α = 0.05). Results: All the aforementioned parameters showed statistically significant differences apart from ECORR and EPROT. The evaluation of qualitative and quantitative results showed that although SLA had higher corrosion resistance compared with ANO, it had less resistance to pitting corrosion. This means that SLA showed increased resistance to uniform corrosion but less resistance if pitting corrosion was initiated. In all cases, MIX showed intermediate behavior. Conclusion: The corrosion resistance of implant-retained superstructures is dependent on the electrochemical properties of the implants involved, and thus different degrees of intraoral corrosion resistance among different implant systems are anticipated.


Asunto(s)
Cromo/química , Cobalto/química , Aleaciones Dentales/química , Ensayo de Materiales , Prótesis e Implantes , Saliva Artificial/química , Titanio/química , Corrosión , Electroquímica , Humanos
6.
Braz Oral Res ; 33: e097, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31664360

RESUMEN

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.


Asunto(s)
Aleaciones/química , Aleaciones Dentales/química , Instrumentos Dentales , Preparación del Conducto Radicular/instrumentación , Análisis de Varianza , Diseño de Equipo , Análisis de Falla de Equipo , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Valores de Referencia , Reproducibilidad de los Resultados , Estadísticas no Paramétricas , Estrés Mecánico , Propiedades de Superficie , Torque
7.
Colloids Surf B Biointerfaces ; 184: 110492, 2019 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-31522026

RESUMEN

The electrochemical properties of CoCrMo alloy immersed in different artificial saliva with or without Ca2+ and albumin were studied by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP), and meanwhile the microstructures features, phase identification and chemical composition of the alloy were analyzed by SEM, EDS, XRD and RA-IR to further understand the electrochemical behavior of the alloy. The results indicated that the self-passivation behavior of the alloy occurred universally and was obviously distinct with each other in different acidic artificial saliva. No phase transformation was observed and the oxide layer and corrosion products exhibited amorphous nature. There was an obvious complexation of the adsorbed albumin with the alloy, and the adsorption capacity of albumin increased with the prolongation of immersion time. The adsorbed albumin presenting black stripped spots had a certain inhibition to the formation of passivation film, and Ca2+ in saliva promoted the further adsorption of albumin as an intermediate bridge, going against the improvement of the corrosion resistance of passivation film/alloy system. In addition, the passivation state of the alloy surface was changed by different methods to investigate the adsorption behavior of albumin and its influence on the further passivation behavior in depth. Hitherto, we tried to propose a model to explain the dynamic adsorption process of albumin and its influencing mechanism on the growth behavior of passivation film.


Asunto(s)
Albúminas/química , Aleaciones de Cromo/química , Cobalto/química , Aleaciones Dentales/química , Molibdeno/química , Saliva Artificial/química , Adsorción , Espectroscopía Dieléctrica , Electroquímica/métodos , Concentración de Iones de Hidrógeno , Ensayo de Materiales/métodos , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Difracción de Rayos X
8.
Int Orthod ; 17(3): 469-477, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31383599

RESUMEN

OBJECTIVE: The aim of this study was to evaluate the effect of intraoral aging and sterilization on the physical properties of rectangular Nickel-Titanium (NiTi), Beta-Titanium and Cooper NiTi (Cu-NiTi) arch wires. METHODS: Three types of preformed 0.018×0.025 inch wires: super elastic NiTi wire, Beta-Titanium wire and Cu-NiTi wire (20 of each type) were divided into 4 groups: as-received (T0), autoclave (T1), intra oral aging after sterilization (T2) and intra oral aging (T3). Specimens in T2 and T3 groups were used in oral environment of 30 participants for 8 weeks. In the next step a length of 30mm was cut from both ends of each arch wire, and 120 straight specimens were achieved and tested by Instron for evaluating their load deflection properties. Data were analysed by means of One-way ANOVA and Tukey's (honestly significant difference) HSD tests. RESULTS: In NiTi wire, all conditions led to a significant decrease in deactivation mean load compared with control in most deflections (P=0.000). In Cu-NiTi wire, all conditions led also to a significant decrease in deactivation mean load compared with the control (P=0.000). In Beta-Titanium wire, sterilization had no significant effect on the load deflection properties; but significant increase was observed in T2 (in all deflections) and T3 (in 1.8-1mm) compared with the control. CONCLUSIONS: After all conditions, NiTi wire in spite of reduction in stiffness presented a mean load which stayed in category of heavy force. The Cu-NiTi wires saw an improvement in light physiologic force. In contrast, the Beta-Titanium stiffness increased after clinical usage, and the force level remained in the range of heavy force.


Asunto(s)
Aleaciones Dentales/química , Ensayo de Materiales , Níquel/química , Alambres para Ortodoncia , Esterilización , Titanio/química , Aleaciones , Análisis de Varianza , Análisis del Estrés Dental/instrumentación , Calor/efectos adversos , Humanos , Fenómenos Mecánicos , Esterilización/métodos , Estrés Mecánico , Resistencia a la Tracción
9.
Photobiomodul Photomed Laser Surg ; 37(7): 442-450, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31265379

RESUMEN

Objective: This study compared the effects of different surface treatments on the surface roughness (Ra), and shear bond strength (SBS) of resin cement to yttria-stabilized tetragonal zirconia (Y-TZP) ceramic and nickel-chromium (Ni-Cr) base metal alloy, respectively. Materials and methods: Thirty disk-shaped specimens (3 mm height and 10 mm diameter) of each material (Y-TZP and Ni-Cr) were prepared. Both zirconia and metal specimens were randomly assigned to three equal groups, according to the surface treatments (n = 10): sandblasting, sandblasting + Er:YAG laser, and sandblasting + Nd:YAG laser. Resin cement cylinders (4 mm diameter and 3 mm thickness) were placed on each specimen. The SBS tests were performed at a 1 mm per minute crosshead speed through a knife-edge rod after 5000 thermal cycles. The Ra (µm) of the specimens was measured using a profilometer and evaluated topographically by atomic force microscopy and scanning electron microscopy. Analysis of variance, followed by Tukey's honestly significant difference, in addition to the Kruskal-Wallis test, followed by the Mann-Whitney U test, were used for statistical analysis (α = 0.05). Results: Combined sandblasting and laser treatment of the metal groups led to statistically higher Ra values than sandblasting alone (p < 0.05). For Y-TZP, there were no significant differences between the Ra values of the subgroups (p > 0.05). The SBS of the sandblasted metal group was significantly higher than the other two laser-irradiated groups, whereas the SBS of sandblasted zirconia was only significantly higher than the Nd:YAG laser-irradiated group (p < 0.05). Conclusions: Combined laser and sandblasting surface treatments resulted in rougher surfaces than sandblasting alone, especially for the metal specimens. Sandblasting, alone, improved the SBS of resin cement in both metal and zirconia, compared with the laser and sandblasting treatments, combined.


Asunto(s)
Aleaciones de Cromo/química , Aleaciones Dentales/química , Recubrimiento Dental Adhesivo/métodos , Grabado Dental/métodos , Porcelana Dental/química , Láseres de Estado Sólido , Cementos de Resina/química , Itrio/química , Circonio/química , Ensayo de Materiales , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Resistencia al Corte/efectos de la radiación , Propiedades de Superficie
10.
Niger J Clin Pract ; 22(7): 926-931, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31293256

RESUMEN

Background: This study was performed to evaluate the amount of apically extruded debris removed from a root canal filled with cold lateral condensation (CLC), and warm vertical compaction (WVC) techniques, using b or a phase gutta-percha with AH-Plus (Dentsply DeTrey, Konstanz, Germany) or Resilon (Resilon Research LLC, Madison, WI) with RealSeal SE (SybronEndo, Amersfoort, The Netherlands). Materials and Methods: About 100 human incisor teeth were prepared with a #25.06 NiTi rotary system and divided into five groups according to the filling material used: Group 1: CLC (gutta-percha, AH-Plus); Group 2: WVC (b phase gutta-percha, AH-Plus); Group 3: WVC (a phase gutta-percha, AH-Plus); Group 4: CLC (Resilon, RealSeal SE); and Group 5: WVC (Resilon, RealSeal SE). Extruded debris during the retreatment procedure was collected in preweighed Eppendorf tubes. The times required for retreatment were recorded. Results: The amount of debris extrusion was significantly greater with WVC than CLC in the gutta-percha and Resilon groups (P < 0.001). Using a phase gutta-percha resulted in significantly more debris extrusion than b phase gutta-percha (P < 0.001). In the WVC groups, Resilon caused significantly more debris extrusion than gutta-percha (P < 0.05). Retreatment was faster for CLC than WVC (P < 0.05). Conclusions: In the retreatment procedure, the amount of apically extruded debris and retreatment duration were dependent on the type of obturation material and technique used.


Asunto(s)
Cavidad Pulpar/cirugía , Gutapercha/química , Materiales de Obturación del Conducto Radicular/química , Preparación del Conducto Radicular/instrumentación , Preparación del Conducto Radicular/métodos , Tratamiento del Conducto Radicular/instrumentación , Aleaciones Dentales/química , Humanos , Níquel , Retratamiento , Materiales de Obturación del Conducto Radicular/efectos adversos , Obturación del Conducto Radicular/métodos , Titanio/química , Ápice del Diente/patología
11.
Dentomaxillofac Radiol ; 48(7): 20190036, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31188678

RESUMEN

OBJECTIVES: To evaluate the effects of syngo WARP on reducing metal artefacts from dental materials. METHODS: Short tau inversion recovery (STIR) with syngo WARP [a dedicated metal artefact reduction sequence in combination with view-angle-tilting (VAT)] was performed using phantoms of three dental alloys: cobalt-chromium (Co-Cr), nickel-chromium (Ni-Cr), and titanium (Ti). Artefact volumes and reduction ratios of black, white and overall artefacts in the standard STIR and syngo WARP images with several different parameter settings were quantified according to standards of the American Society for Testing and Materials F2119-07. In all sequences, the artefact volumes and reduction ratios were compared. The modulation transfer function (MTF) and contrast-to-noise ratio (CNR) were also measured for evaluation of image quality. RESULTS: In standard STIR, the overall artefact volume of Co-Cr was markedly larger than those of Ni-Cr and Ti. All types of artefacts tended to be reduced with increasing receiver bandwidth (rBW) and VAT. The effect of artefact reduction tended to be more obvious in the axial plane than in the sagittal plane. Compared with standard STIR, syngo WARP with a matrix of 384 × 384, receiver bandwidth of 620 Hz/pixel, and VAT of 100 % in the axial plane obtained reduction effects of 30 % (white artefacts), 45 % (black artefacts), and 38 % (overall artefacts) although MTF and CNR decreased by 30 and 22 % compared with those of standard STIR, respectively. CONCLUSIONS: syngo WARP for STIR can effectively reduce metal artefacts from dental materials.


Asunto(s)
Artefactos , Aleaciones Dentales , Radiografía Dental , Aleaciones Dentales/química , Aumento de la Imagen , Imagen por Resonancia Magnética , Fantasmas de Imagen , Radiografía Dental/métodos
12.
Microsc Res Tech ; 82(9): 1384-1391, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31111992

RESUMEN

The aims of this study were: (a) to determine if the presence of probiotic bacteria in an aging medium, that is, artificial saliva in this study, has relevant effects on the surface roughness and the chemical composition of two main alloys used in dentistry (NiTi and stainless steel [SS]) and (b) in the case of NiTi, if these effects are influenced by the coating of the alloy (rhodium and titanium nitride). Atomic force microscopy and Raman spectroscopy were used to study the surface morphology and identify metal oxides formed on the surface of the alloys. Experiments demonstrated that the probiotic bacteria Lactobacillus reuteri can induce processes that alter some features of the surface such as roughness and chemical composition. The effect is dependent on the type of alloy and coating. The bacteria increased roughness in the case of uncoated NiTi more than saliva alone (pH = 4.8). Probiotic bacteria tend to decrease the corrosive influence of saliva on NiTi when the alloy is coated with rhodium or titanium nitride and this effect was also evidenced on SS. Raman spectroscopy confirmed that only SS samples are prone to oxidation processes, predominantly associated with exposure to saliva rather than probiotic bacteria.


Asunto(s)
Aleaciones Dentales/química , Lactobacillus reuteri/crecimiento & desarrollo , Lactobacillus reuteri/metabolismo , Probióticos/metabolismo , Saliva/microbiología , Propiedades de Superficie , Corrosión , Microscopía de Fuerza Atómica , Óxidos/análisis , Espectrometría Raman
13.
Niger J Clin Pract ; 22(4): 496-502, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30975953

RESUMEN

Aim: The aim of this research was to investigate the effect of microwave glazing, conventional oven glazing, and polishing on surface roughness and wettability of porcelains. Materials and Methods: The initial surface roughness values (Ra0) of the prepared specimens for four different porcelains (Vita VM 9, VitaVM 13, Vita VMK 95, IPS e.maxCeram) were determined by profilometry. Then, the specimens were divided randomly into three groups as polishing, conventional oven glazing, and microwave glazing. Final surface roughness values were evaluated by profilometry (Ra1) and scanning electron microscopy. Wettability of glazed specimens were evaluated by contact angle goniometer. Results: Although microwave-glazed specimens had lower Ra1 values compared with the conventional oven-glazed ones for IPS e.maxCeram (P < 0.05), there were not any statistically significant differences between these two procedures in terms of Ra1 values for the other porcelains (P > 0.05). Microwave-glazed specimens had lower wettability values than conventional oven-glazed ones for Vita VM 9. Conclusions: Microwave glazing procedure may be considered as an alternative method because of the advantages of providing volumetric heating, time, and energy saving.


Asunto(s)
Aleaciones Dentales/química , Pulido Dental/métodos , Porcelana Dental/química , Ensayo de Materiales/métodos , Microscopía Electrónica de Rastreo , Microondas , Humectabilidad , Cerámica , Calor , Humanos , Propiedades de Superficie
14.
Int Orthod ; 17(1): 80-88, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30765237

RESUMEN

INTRODUCTION: There are controversies regarding the most reliable conditioning method of the aged composite surface to ensure optimum bond strength. The purpose of this study was to evaluate the shear bond strength of metal brackets to microhybrid composite restorations after different surface preparation techniques. MATERIALS AND METHODS: A total of sixty microhybrid composite samples were prepared using upper right central incisor celluloid crown as a mold. Samples were treated with 4 different surface conditioning methods: (1) etching, (2) sandblasting, (3) grinding, and (4) CO2 laser irradiation. Samples were then bonded with metal brackets and underwent shear bond strength testing. A scanning electron microscope was carried out and the data was analysed by one-way ANOVA and post-hoc Tukey test. Bond failure was examined by stereomicroscope and scored based on adhesive remnant index (ARI). Kruskal-Wallis test was used to compare ARI values (α=0.05). RESULTS: Shear bond strength values in the sandblasting group (17.18±1.53MPa) were significantly higher than the other groups. There was no significant difference between the grinding (12.87±3.38MPa) and laser (11.08±1.37MPa) groups (P=0.09). The lowest values were recorded in the etching group (6.78±1.69MPa). There was a significant difference in ARI scores among the four groups (P<0.001). ARI scores were mostly 2 and 3 in the sandblasting and grinding group, while in the etching and laser groups ARI was mostly 0 and 1. CONCLUSIONS: Surface preparation by sandblasting and CO2 laser provides clinically acceptable results with regards to bond strength and ARI score, however grinding and acid etching failed to produce the same results.


Asunto(s)
Aleaciones Dentales/química , Recubrimiento Dental Adhesivo/métodos , Soportes Ortodóncicos , Resistencia al Corte , Resinas Acrílicas , Abrasión Dental por Aire/métodos , Grabado Dental/métodos , Fracaso de la Restauración Dental , Humanos , Incisivo , Láseres de Gas , Ensayo de Materiales , Maxilar , Metales , Ácidos Fosfóricos , Cementos de Resina/química , Propiedades de Superficie
15.
Int Orthod ; 17(1): 60-72, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30777734

RESUMEN

BACKGROUND AND AIM: Surface topography is a crucial factor in bracket sliding mechanics. Literature on surface roughness of aesthetic archwires is scarce, and there is no study on surface topography of such archwires affected by any sterilization methods. The aim of this study was to compare the surface topography of plain nickel-titanium (NiTi) versus as-received aesthetic coated NiTi wires versus aesthetic wires sterilized by autoclaving or glutaraldehyde immersion. MATERIALS AND METHODS: This in vitro study was performed on 80 atomic force microscopy (AFM) observations, 160 profilometry observations, and 40 scanning electron microscopy (SEM) images from rectangular wires of the brands 'American Orthodontics, Ortho Organizers, SIA, and Gestenco'. AFM consisted of 8 subgroups of NiTi orthodontic wires, consisting of 4 subgroups of 4 brands of coated orthodontic wires and 4 subgroups of 4 brands of uncoated wires from the same brands. Profilometry consisted of 16 subgroups of NiTi orthodontic wires, consisting of 4 subgroups of 4 brands of coated orthodontic wires and 12 subgroups of 4 brands of uncoated wires from the same brands (4 as-received wire subgroups, 4 autoclaved, and 4 cold-sterilized subgroups). Scanning electron microscopy (SEM) and AFM images were subjectively evaluated. AFM and profilometry data were analysed statistically (α=0.05). RESULTS: Overall, the difference between surface roughness parameters of coated versus uncoated archwires was not significant (P>0.05). However, surface roughness of brands differed significantly. Mann-Whitney did not show any significant differences between sterilized wires (both sterilization methods together as one group) and unsterilized wires (both unsterilized coated and uncoated as one group) (P>0.460). After excluding plain uncoated NiTi group, the coated wires in 3 sterilization groups (no sterilization, autoclaving, glutaraldehyde) were not significantly different in terms of average overall surface roughness (Ra) and maximum roughness depths (Rq) of different sterilization groups (P>0.1) but the average maximum peak to valley heights (Rz) values of 3 sterilization groups were significantly different (P=0.0415). Dunn test showed that among three post-hoc pairwise comparisons of Rz values, only the comparison of "no sterilization versus autoclaving" was significant (P<0.05) and the other two were non-significant. CONCLUSION: Coating might not affect the surface roughness considerably. Brands have different surface roughnesses. Autoclaving but not cold sterilization might affect the surface roughness of coated archwires.


Asunto(s)
Microscopía de Fuerza Atómica/métodos , Microscopía Electrónica de Rastreo/métodos , Níquel/química , Soportes Ortodóncicos , Alambres para Ortodoncia , Esterilización/métodos , Titanio/química , Aleaciones Dentales/química , Estética Dental , Glutaral , Humanos , Ensayo de Materiales , Diseño de Aparato Ortodóncico , Propiedades de Superficie
16.
PLoS One ; 14(1): e0210530, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30703125

RESUMEN

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.


Asunto(s)
Aleaciones Dentales/química , Implantes Dentales/normas , Ensayo de Materiales/métodos , Titanio/química , Ácidos/química , Corrosión , Técnicas Electroquímicas/métodos , Humanos , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Inflamación/inducido químicamente , Inflamación/complicaciones , Microscopía Electrónica de Rastreo , Modelos Químicos , Propiedades de Superficie
17.
J Int Med Res ; 47(2): 803-814, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30616411

RESUMEN

OBJECTIVE: To examine the effect of clinical use on both force retention and the deactivation of closed-coil nickel-titanium (NiTi) springs in a 16-week trial. METHODS: The force-activation curves for NiTi springs were determined before and after clinical use. The rate of tooth movement and maximum force (MF), hysteresis between activation and deactivation, and mean force of the deactivation plateau (MDF) were examined and correlated as a function of 4, 8, 12 and 16 weeks of clinical use. To recover the force properties, the springs were heat treated at 100°C and the results were compared with the preceding data. RESULTS: A total of 36 springs were analysed. The MF loss after use was 60, 74, 55, and 48 g for the 4-, 8-, 12- and 16-week springs, respectively. Heat treating had little effect on the MF. Clinical use lowered hysteresis by a mean of 180 g*mm compared with the pre-clinical use data, and heat treating increased the hysteresis by a mean of 59 g*mm above the post clinic testing data. The MDF was nominally 100 g less than the MF. Teeth moved approximately 1 mm/month, independent of the force loss. CONCLUSIONS: The loss of MF and the lowering of the MDF was not time dependent. Heat treating can partially recover the mechanical properties of the used springs.


Asunto(s)
Aleaciones Dentales/química , Níquel/química , Cierre del Espacio Ortodóncico/instrumentación , Alambres para Ortodoncia , Titanio/química , Adolescente , Niño , Femenino , Estudios de Seguimiento , Humanos , Masculino , Ensayo de Materiales , Fenómenos Mecánicos , Pronóstico , Estudios Prospectivos
18.
J Prosthodont ; 28(1): e265-e270, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29271021

RESUMEN

PURPOSE: To evaluate the effect of the triad finish line design, axial wall convergence angle, and luting cement on the marginal fit of metal copings used in metal-ceramic crowns. MATERIALS AND METHODS: Schematic dies and their respective copings were cast in NiCr alloy. The dies exhibited the following finish line/convergence angle combinations: sloping shoulder/6°, sloping shoulder/20°, shoulder/6°, shoulder/20°. Marginal fit was evaluated under a stereomicroscope, before and after cementation. Copings were air-abraded with 50 µm Al2 O3 particles and cemented with Cimento de Zinco, RelyX U100, or Panavia F cements (n = 10/group). Data were square-root transformed and analyzed by 3-way factorial random effect model and Tukey's post hoc test (α = 0.05). RESULTS: Statistical analysis showed significance for the interactions finish line and convergence angle (p < 0.05), convergence angle and time (p < 0.001), and luting cement and time (p < 0.001). Sloping shoulder/20° provided the highest marginal discrepancy when compared to the other finish line/convergence angle combinations, which were statistically similar among each other. For both convergence angles and for all luting cements, the marginal discrepancy was significantly higher after cementation. Before and after cementation, 6° provided better marginal fit than 20°. After cementation, Panavia F provided higher marginal discrepancy than Cimento de Zinco. CONCLUSION: Lower convergence angle combined with shoulder and a low-consistency luting cement is preferable to cement metal copings.


Asunto(s)
Cementación/métodos , Cementos Dentales/química , Adaptación Marginal Dental , Ensayo de Materiales , Aleaciones de Cerámica y Metal/química , Preparación Protodóncica del Diente/métodos , Aleaciones Dentales/química , Porcelana Dental/química , Diseño de Prótesis Dental , Fracaso de la Restauración Dental , Cementos de Ionómero Vitreo/química , Humanos , Cementos de Resina , Estrés Mecánico , Propiedades de Superficie , Preparación del Diente/métodos
19.
Int Endod J ; 52(1): 94-104, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29969837

RESUMEN

AIM: To assess the real-time dynamic torque values and axial forces during preparation of straight root canals using three different endodontic motors and hand preparation. METHODOLOGY: Sixty maxillary incisors were divided into four homogeneous groups (n = 15). After glide path establishment (size 20) the root canals were prepared to an apical size 40 using the rotary NiTi system F6 SkyTaper. Motors (DentaPort ZX OTR, EndoPilot and VDW.silver) were set to 'auto-torque-reverse' mode and DentaPort ZX was set to its specific OTR mode (optimum torque reverse). One group served as a control using manual balanced-force canal preparation with K-Flexofiles. Teeth were embedded in resin and fixed in a multi-component sensor measuring axial and torsional load during active instrumentation with 50 Hz. Preparation time was also recorded. Data were statistically analysed using the Kruskal-Wallis test. RESULTS: The maximum axial forces (peak) and both peaks of dynamic clockwise and counter-clockwise torque did not differ significantly when using the three different motors despite different gear ratios and pre-settings. Only the VDW.silver motor exceeded the torque values during the use of 30 instruments (3.3%). The Morita OTR motor exceeded the maximum intrinsic torque set at 1.0 Ncm in approximately 53% of cases. The larger tapered F6 SkyTaper instruments (size 20, .06 taper and size 30, .06 taper) created significantly higher torque values (P < 0.0001). Manual instrumentation created significantly lower torque levels and higher axial values compared to rotary instrumentation (P < 0.0001) and was significantly more time consuming (P < 0.0001). CONCLUSIONS: Manual preparation was associated with significantly lower torque peaks compared to rotary instrumentation. The three motors remained well within the safety torque values of the instruments.


Asunto(s)
Instrumentos Dentales , Equipos y Suministros Eléctricos , Preparación del Conducto Radicular/instrumentación , Estrés Mecánico , Torque , Aleaciones Dentales/química , Análisis del Estrés Dental , Diseño de Equipo , Humanos , Incisivo/anatomía & histología , Níquel/química , Rotación , Titanio/química
20.
Int Endod J ; 52(1): 86-93, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29858500

RESUMEN

AIM: To evaluate and compare the canal shaping ability of BioRace, ProTaper NEXT and Genius engine-driven nickel-titanium (NiTi) file systems in extracted mandibular first molars using micro-computed tomography (MCT). METHODOLOGY: Sixty mesial root canals of mandibular first molars were randomly divided into three equal groups, according to the instrument system used for root canal preparation (n = 20): BioRace (BR), ProTaper NEXT (PTN) or Genius (GN). Root canals were prepared to the full WL using a crown-down technique up to size 35, .04 taper instruments for BR and GN groups and size 30, .07 taper instruments for the PTN group. MCT was used to scan the specimens before and after canal instrumentation. Changes in dentine volume, the percentage of uninstrumented canal surface and degree of canal transportation were evaluated in the coronal, middle and apical thirds of canals. Data were analysed statistically using one-way analysis of variance and Tuckey's post hoc tests with the significance level set at 5%. RESULTS: There were no significant differences between the three groups in the terms of dentine removed after preparation and determination of the root canal volume, or percentage of uninstrumented canal surface (P > 0.05). No significant differences were found between the systems for canal transportation in any canal third (P > 0.05). CONCLUSIONS: The shaping ability of the BR, PTN and GN NiTi file systems was equally effective. All instrumentation systems prepared curved root canal systems with no evidence of undesirable changes in 3D parameters or significant shaping errors.


Asunto(s)
Aleaciones Dentales/química , Níquel/química , Preparación del Conducto Radicular/instrumentación , Titanio/química , Microtomografía por Rayos X/métodos , Análisis de Varianza , Instrumentos Dentales , Cavidad Pulpar/anatomía & histología , Cavidad Pulpar/diagnóstico por imagen , Dentina/anatomía & histología , Dentina/patología , Diseño de Equipo , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Técnicas In Vitro , Mandíbula/anatomía & histología , Mandíbula/diagnóstico por imagen , Diente Molar/anatomía & histología , Diente Molar/diagnóstico por imagen , Diente Molar/cirugía , Preparación del Conducto Radicular/métodos , Propiedades de Superficie
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