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1.
Dental Press J Orthod ; 26(2): e212020, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33950083

RESUMO

INTRODUCTION: After debonding, white spot may appear on the area below the bracket, which is the early clinical sign of carious lesion. There is increased caries risk underneath and adjacent to orthodontic bands and brackets, which call for maximum use of caries preventive procedures using various fluoride application methods. OBJECTIVE: The aim of the study was to evaluate alterations in the mechanical properties (modulus of elasticity and yield strength) in loading and unloading phases for different orthodontic archwires (nickel-titanium [NiTi] and copper-nickel-titanium [CuNiTi]) when exposed routinely to fluoride prophylactic agents for a predetermined period of time. METHODS: Preformed rectangular NiTi and CuNiTi wires were immersed in fluoride solution and artificial saliva (control) for 90 minutes at 37ºC. After immersion, specimens were tested using a 3-point bend test on a universal testing machine. RESULTS: There is a significant reduction in the unloading yield strength when the NiTi and CuNiTi wires were exposed to APF gel. CONCLUSION: The result suggests that use of topical fluoride agents affect the mechanical properties of the wires, leading to increase in treatment duration. Fluoride prophylactic agents must be used with caution in patients undergoing orthodontic treatment. Injudicious use of these agents may cause corrosive effects on the orthodontic wire surfaces, with alteration in their mechanical properties.


Assuntos
Níquel , Fios Ortodônticos , Cobre , Ligas Dentárias , Fluoretos , Humanos , Teste de Materiais , Níquel/efeitos adversos , Propriedades de Superfície , Titânio
2.
Dent Mater ; 37(4): 588-596, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33581911

RESUMO

OBJECTIVES: Previous studies have shown that the use of Cu electrodes compromises the electrochemical properties of Co-Cr and Ti alloys used for the fabrication of implant retained superstructures by Electro Discharge Machining (EDM). A possible solution is the use of Ti instead of Cu electrodes and thus the aim of this study was to evaluate the effect of Cu and Ti electrodes on surface and electrochemical properties of two types of dental alloys used for fabrication of implant retained superstructures after EDM. METHODS: Three full arch frameworks were prepared from a Co-Cr and three from Ti6Al7Nb alloy. One framework from each alloy was used as control, one was subjected to EDM with Cu electrodes and the last one with Ti electrodes. Morphological and elemental characterization was studied by SEM/EDX. The electrochemical properties of the alloys were evaluated by Open Circuit Potential (OCP) and Linear Sweep Voltammetry (LSV) in Ringer's solution. Electrochemical data were analyzed statistically by one way ANOVA and SNK multiple comparison tests at a = 0.05 RESULTS: All groups demonstrate the typical surface after EDM treatment with almost circular valleys and an increase in C and O content compared to control groups. Both alloys demonstrated an uptake of C and Cu by Cu electrodes and C and Ti after treatment with Ti electrodes. The use of Cu electrodes had a detrimental effect on corrosion resistance of Ti alloy. SIGNIFICANCE: The use of Ti electrodes mitigates the degradation of electrochemical properties compared to Cu electrodes and from this standpoint is safer for the EDM of implant retained superstructures made of Co-Cr and Ti alloys.


Assuntos
Ligas Dentárias , Titânio , Ligas , Corrosão , Eletrodos , Humanos , Teste de Materiais , Alta do Paciente , Propriedades de Superfície
3.
J Endod ; 47(5): 836-843, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33387551

RESUMO

The preparation of severely curved S-shaped double-curved root canals can be technically challenging. A novel root canal instrumentation technique is proposed, which modifies 2 techniques: the McSpadden crown-down technique and the tactile controlled activation technique. In the McSpadden crown-down technique, the root canal is divided into 2 portions: the coronal zone and the apical zone. However, rather than focusing on the length of file engagement, a formula is proposed to calculate the maximum insertion depths of higher tapered instruments to prevent overflaring of the canal and preserve pericervical dentin. Tactile-controlled activation involves activating martensitic nickel-titanium rotary files upon engagement and then immediately withdrawing the files. The proposed technique recommends 3 apical strokes after the initial engagement before withdrawal to minimize instrumentation time. This novel technique is described in a case report involving the management of an S-shaped double-curved maxillary lateral incisor. The technique presents a new method of crown-down instrumentation that prevents overflaring and avoids instrument separation.


Assuntos
Cavidade Pulpar , Preparo de Canal Radicular , Coroas , Ligas Dentárias , Cavidade Pulpar/diagnóstico por imagem , Desenho de Equipamento , Humanos , Dente Molar , Tratamento do Canal Radicular , Titânio
4.
Braz. dent. sci ; 24(2): 1-10, 2021. tab, ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1178333

RESUMO

Objective: The aim of this experimental study was to assess the effect of khat extract with different concentrations on the corrosion resistance of cobalt-chromium (Co-Cr) dental alloys used for removable denture. Material and Methods:The corrosion resistance of three Co-Cr alloys (Neobond II®, Kera 501® and PD Casta H®) was evaluated in artificial saliva in presence of three different concentrations of khat extracts. Fusayama-Meyer artificial saliva was used as a reference solution. The corrosion properties of the alloys were analyzed using potentiodynamic polarization, electrochemical impedance spectroscopy and surface analysis. The data was presented in means, standard deviations, and related figures. Comparison between the different concentrations was done using 1-way ANOVA test. The surface analysis was performed using scanning electron microscopy (SEM). Results: the results showed that the corrosion resistance of the three alloys tested (Neobond II®, Kera 501® and PD Casta H®) decreased in artificial saliva containing khat extract compared with that of the reference solution. Additionally, the corrosion resistance of the three Co-Cr dental alloys decreased by increasing the concentration of khat extract. Furthermore, the results indicate that Neobond II® alloy showed the least corrosion resistance compared with that of Kera 501® and PD Casta H® alloys. Conclusion: Khat extract with different concentrations had negative impact on the corrosion resistance of Cr-Co alloys. More in-vivo studies are highly recommended to confirm the results of the present study (AU)


Objetivo: O objetivo deste estudo experimental foi avaliar o efeito do extrato de khat em diferentes concentrações na resistência à corrosão de ligas dentárias de cobalto-cromo (Co-Cr) utilizadas em próteses removíveis. Material e Métodos:A resistência à corrosão de três ligas de Co-Cr (Neobond II®, Kera 501® e PD Casta H®) foi avaliada em saliva artificial na presença de três concentrações diferentes de extratos khat. A saliva artificial de Fusayama-Meyer foi usada como solução de referência. As propriedades de corrosão das ligas foram analisadas usando polarização potenciodinâmica, espectroscopia de impedância eletroquímica e análise de superfície. Os dados foram apresentados em médias, desvios-padrão e figuras relacionadas. A comparação entre as diferentes concentrações foi feita usando o teste One-way ANOVA. A análise de superfície foi realizada em microscopia eletrônica de varredura (MEV). Resultados: os resultados mostraram que a resistência à corrosão das três ligas testadas (Neobond II®, Kera 501® e PD Casta H®) diminuiu na saliva artificial contendo extrato khat em comparação com a solução de referência. Além disso, a resistência à corrosão das três ligas dentais Co-Cr diminuiu com o aumento da concentração de extrato de khat. Além disso, os resultados indicam que a liga Neobond II® apresentou a menor resistência à corrosão em comparação com as ligas Kera 501® e PD Casta H®. Conclusão: O extrato de Khat com diferentes concentrações teve impacto negativo na resistência à corrosão de ligas de Cr-Co. Mais estudos in vivo são altamente recomendados para confirmar os resultados do presente estudo. (AU)


Assuntos
Catha , Ligas Dentárias , Corrosão Dentária , Prótese Parcial
5.
J Clin Pediatr Dent ; 44(6): 451-458, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33378466

RESUMO

OBJECTIVE: The surface roughness of various orthodontic materials could affect biofilm formation and friction. The purpose of this study was to examine the surface roughness and chemical composition of the slots and wings of several ceramic self-ligating brackets. STUDY DESIGN: Four types of ceramic self-ligating brackets were separated into experimental groups (DC, EC, IC, and QK) while a metal self-ligating bracket (EM) was used as the control group. Atomic force microscopy and energy-dispersive x-ray spectroscope were used to examine the surface roughness and chemical composition of each bracket slot and wing. RESULTS: The control group was made of ferrum and chrome while all the experimental groups were comprised of aluminum and oxide. There was a statistically significant difference in the roughness average (Sa) among the various self-ligating brackets (p< 0.001 in slots and p<0.01 in the wing). The slots in the EC group had the lowest Sa, followed by the DC, IC, control, and QK groups. The wings in the IC group had the lowest Sa, followed by the EC, DC, control, and QK groups. CONCLUSIONS: There is a significant difference in the surface roughness of the slots and wings among several types of ceramic self-ligating brackets.


Assuntos
Braquetes Ortodônticos , Biofilmes , Cerâmica , Ligas Dentárias , Fricção , Humanos , Teste de Materiais , Desenho de Aparelho Ortodôntico , Fios Ortodônticos , Aço Inoxidável , Propriedades de Superfície
7.
Sci Rep ; 10(1): 22280, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33335223

RESUMO

The metal alloys used in dentistry are made mainly of nickel (Ni), titanium (Ti), and other elements such as molybdenum (Mo), zirconium (Zr), iron (Fe), tin (Sn), chrome (Cr), carbon (C), copper (Cu) and niobium (Nb) which can release metal ions in unstable environments. The aim of this work was determine the salivary pH before and during orthodontic treatment; evaluate the release of metal ions, mainly Ni and Ti, in urine and saliva using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES); and evaluate the corrosion using Scanning Electronic Microscopy (SEM). In this study, we selected 35 individuals under orthodontic treatment, from whom saliva and urine samples were collected in 3 stages: (a) basal, (b) at 3 and (c) 6 months after the placement of the fixed appliances. SEM analyzed the Ni-Ti (0.016″) and stainless steel (SS) (0.016 × 0.022″) archs after 1 month of being in contact with the oral cavity. Statistical analysis was performed with Stata using the ANOVA model of repeated measures with a p < 0.05. A statistically significant difference in the concentration of Ni in saliva were found between 3 and 6 months of intervention and Ti in urine was found 3 and 6 months.


Assuntos
Ligas Dentárias/uso terapêutico , Níquel/uso terapêutico , Saliva/efeitos dos fármacos , Titânio/uso terapêutico , Adolescente , Ligas/química , Ligas/uso terapêutico , Criança , Cobre/uso terapêutico , Cobre/urina , Ligas Dentárias/efeitos adversos , Feminino , Humanos , Íons/urina , Ferro/uso terapêutico , Ferro/urina , Masculino , Molibdênio/uso terapêutico , Molibdênio/urina , Níquel/efeitos adversos , Níquel/urina , Nióbio/uso terapêutico , Nióbio/urina , Aço Inoxidável/química , Titânio/efeitos adversos , Titânio/urina , Zircônio/uso terapêutico , Zircônio/urina
8.
Orthod Fr ; 91(3): 249-262, 2020 10 01.
Artigo em Francês | MEDLINE | ID: mdl-33146619

RESUMO

The use of self-ligating brackets has largely developed in orthodontic practice thanks to numerous advantages, including the reduction of frictional forces during sliding orthodontic mechanic. Faced with scientific evidence, this advantage still seems to be debatable. Our objective was to evaluate in vivo the frictional force of self-ligating brackets by searching for micro-morphological and chemical effects on the active slot surface, after phase of alignment-leveling and after a period in the mouth. 16 brackets from four commercial brands were selected (Damon®, In-Ovation®, Smart-clip® and Carriere®). These brackets were visualized using a scanning electron microscope (SEM) and dispersive energy spectroscopy to study their surface and initial chemical composition. After a period in the mouth, these brackets were debonded and evaluated with SEM, to search topographic and chemical changes in relation to the frictional forces. After a period of three months used for dental alignment, all the brackets show considerable changes in topographic and chemical properties related to frictional forces, with deposit of organic debris whose importance is related to the initial surface different from one manufacturer to another.


Assuntos
Braquetes Ortodônticos , Fios Ortodônticos , Ligas Dentárias , Análise do Estresse Dentário , Fricção , Teste de Materiais , Desenho de Aparelho Ortodôntico , Aço Inoxidável , Propriedades de Superfície
9.
J Contemp Dent Pract ; 21(6): 636-639, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33025932

RESUMO

AIM: Variation in the surface roughness of archwires not only leads to more accumulation of plaque but also modifies the coefficient of friction. This necessitated for the present study to evaluate the surface characteristics of 0.016 × 0.022-inch nickel-titanium, beta-titanium, and copper-nickel-titanium archwires, before and after their use in the oral cavity using atomic force microscopy. MATERIALS AND METHODS: The control and experimental samples were measured at three different positions under atomic force microscopy. The surface roughness was measured using roughness average, root mean square, and maximum height before and after use in the oral cavity among 60 adult participants. Data were analyzed using a one-way analysis of variance and Student's t tests using the Statistical Package for Social Software (SPSS) v.20.0. RESULTS: The surface roughness of archwires increased considerably after their clinical use compared to controls for nickel-titanium (p = 0.013) and beta-titanium (p = 0.002). A similar trend was noticed for root mean square where nickel-titanium (p = 0.014) and beta-titanium (p = 0.013) had increased root mean square. Maximum height was also noticed in nickel-titanium (p = 0.031) and beta-titanium (p = 0.016). CONCLUSION: Surface roughness and the level of friction of the orthodontic wires increase significantly for nickel-titanium and beta-titanium after the clinical use. There is a difference in increase of surface roughness of the archwire within and between the bracket slots. CLINICAL SIGNIFICANCE: Nickel-titanium and beta-titanium wires show more roughness and resultant higher friction levels after use in the oral cavity. Hence, care related to plaque accumulation is essential.


Assuntos
Cobre , Níquel , Ligas Dentárias , Humanos , Teste de Materiais , Propriedades de Superfície , Titânio
10.
Dental Press J Orthod ; 25(4): 51-58, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32965387

RESUMO

OBJECTIVE: To investigate the effect of ZnO nanocoating on mechanical properties of NiTi orthodontic wires and antibacterial activity. METHODS: 0.016 x 0.022-in NiTi orthodontic wires were coated with ZnO nanoparticles using an electrochemical deposition method with three electrodes system in 0.1M Zn(NO3)2. Mechanical properties and frictional resistance of the coated wires were investigated using an universal testing machine. Antibacterial effect of ZnO coating was also investigated. RESULTS: A stable adhered ZnO nanocoating on NiTi wires was obtained. The coated wires have a significant antibacterial activity against S. aureus, S. pyogens and E. coli, and a reduction of frictional forces by 34%. CONCLUSION: ZnO nanocoating may improve the antibacterial effects of NiTi wires and reduce the frictional resistance. Coating may be implanted in orthodontic practice for faster and safer treatment.


Assuntos
Óxido de Zinco/farmacologia , Antibacterianos/farmacologia , Ligas Dentárias , Escherichia coli , Teste de Materiais , Níquel , Fios Ortodônticos , Staphylococcus aureus , Propriedades de Superfície , Titânio/farmacologia , Zinco
11.
J Endod ; 46(12): 1884-1893, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32898557

RESUMO

INTRODUCTION: This study aimed to compare the ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland) system with 6 replicalike instruments regarding instrument design, mechanical performance, and alloy characteristics. METHODS: New rotary instruments (size 20/.07v) of PTU and 6 replicalike systems (EdgeTaper [EdgeEndo, Johnson City, TN], U-File [Dentmark, Ludhiana, India], Go-Taper Universal [Access, Shenzhen, China], Super Files [Flydent, Shenzhen, China], Multitaper [Proclinic Expert, Besançon, France], and Pluri Taper [Bestdent, Shenzhen, China]) (n = 329) were selected and evaluated regarding their design, mechanical performance, and metallurgical characteristics. The results were compared using the nonparametric Mood median test and 1-way analysis of variance with the significance level set at 0.05. RESULTS: Replicalike instruments were similar to PTU regarding design, maximum torque to fracture (P > .05), and ratio of nickel and titanium elements. Scanning electron microscopy revealed differences in the geometry of the tip and finishing surfaces. Time to fracture of Go-Taper Universal (50.0 seconds) was similar to PTU (44.0 seconds) (P > .05), but the U-File (63.5 seconds), Edge Taper (87.5 seconds), and Super Files (130 seconds) showed significantly higher values (P < .05). The highest maximum torque was observed in the Super Files instrument (P < .05), but no statistical difference was noted among the other instruments (P > .05). The angle of rotation before rupture of the Multitaper (574°) and Pluri Taper (481°) was higher than PTU (354°) (P < .05). Differential scanning calorimetric analysis showed clear differences on the transformation temperatures among the tested instruments. The R-phase start and finish temperatures of PTU were 11.0°C and -18.0°C, respectively. CONCLUSIONS: Overall, replicalike instruments were similar to PTU regarding the torsional resistance, geometric design, and near equiatomic proportions of nickel and titanium elements. In 3 of the 4 mechanical tests, the EdgeTaper (torque, angle of rotation, and bending load) and Go-Taper Universal (time to fracture, torque, and angle of rotation) systems were similar to PTU.


Assuntos
Ligas Dentárias , Preparo de Canal Radicular , China , Desenho de Equipamento , Falha de Equipamento , França , Índia , Teste de Materiais , Estresse Mecânico , Titânio , Torção Mecânica
12.
PLoS One ; 15(9): e0238790, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32903275

RESUMO

The potential mechanical impact of different rotary systems used for root canal preparation has been a matter of debate for long. The aim of this study was to explore the incidence of dentinal cracks after root canal instrumentation with various rotary systems, in vitro. One hundred and eighty intact lower central incisors were selected and randomly divided into fourteen treatment groups (n = 12/group) and a control group (n = 12). After decoronation, the root canals were instrumented with fourteen different rotary systems (E3, E3 azure, NT2, Hyflex CM, Hyflex EDM, 2Shape, OneCurve, ProTaper Next, ProTaper Gold, WaveOne Gold, Mtwo, Reciproc Blue, TF adaptive, K3XF). All roots were horizontally sectioned at 3, 6, and 9 mm from the apex with a low-speed saw under water-cooling. The slices were then examined under stereomicroscope for dentinal cracks. No cracks were found in the control group. Cracks were found in all treatment groups, predominantly in the 3 mm slices. There was no statistically significant difference in the number of cracks when comparing the different systems to each other at any section level. At 3 mm, however, five of the studied systems, namely K3XF (p = 0.004), Protaper Next (p = 0.001), Reciproc Blue (p<0.001), TF adaptive (p = 0.050), and 2Shape (p = 0.009) presented a significantly higher number of cracks than the control group. Within the limitations of this study, instrumented canals presented dentinal cracks, while uninstrumented ones presented no cracks after sectioning. There seems to be no significant difference among the tested systems regarding crack formation in the instrumented root canal wall. Crack formation occurred irrespective of the motion of the rotary system (rotational or reciprocation). Further studies are needed to clarify the factors that contribute to crack formation in the case of each individual rotary system.


Assuntos
Níquel , Preparo de Canal Radicular/instrumentação , Titânio , Ligas Dentárias , Dentina/lesões , Desenho de Equipamento , Humanos , Técnicas In Vitro , Tratamento do Canal Radicular/métodos
13.
J Endod ; 46(10): 1485-1494, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32721485

RESUMO

INTRODUCTION: This study aimed to compare the mechanical and metallurgical properties and shaping ability of different rotary systems using a multimethod approach. METHODS: New NeoNiti A1 (Neolix SAS, Châtres-La-Forêt, France), HyFlex EDM One File (Coltène/Whaledent, Altstätten, Switzerland), ProTaper Gold F2 (Dentsply Maillefer, Ballaigues, Switzerland), and ProTaper Universal F2 (Dentsply Maillefer) rotary instruments were tested regarding cyclic fatigue, torsional resistance, design, and morphologic characteristics using scanning electron microscopy, metal alloy characterization using differential scanning calorimetry, and energy-dispersive X-ray spectroscopy. Additionally, their shaping ability on the preparation of 48 canals of maxillary molars was evaluated using micro-computed tomographic technology. Mechanical and metallurgical analyses were compared using analysis of variance post hoc Tukey tests, whereas the independent Student t test was used to compare the shaping ability of the ProTaper systems or the thermomechanically treated instruments. The significance level was set at 5%. RESULTS: The highest cyclic fatigue was observed with the NeoNiti and HyFlex EDM instruments (P > .05), whereas HyFlex EDM had the highest angular rotation to fracture (P < .05). Scanning electron microscopic/energy-dispersive X-ray spectroscopic analyses confirmed similarities in the instruments' design and an almost equiatomic composition of the systems. Differential scanning calorimetry showed that ProTaper Gold had higher transformation temperatures than ProTaper Universal, whereas a similar transformation was observed between NeoNiti and HyFlex. Micro-computed tomographic analysis revealed that, despite the fact that none of the systems was able to prepare all root canal walls, no statistical differences were observed in either ProTaper systems (P > .05) or the thermomechanically treated instruments (P > .05). CONCLUSIONS: Apart from differences in the mechanical tests and metallurgical characterization, systems with comparable instrument dimensions and preparation protocols showed a similar percentage of untouched surface areas in the root canal preparation of maxillary molars.


Assuntos
Níquel , Titânio , Ligas , Ligas Dentárias , Desenho de Equipamento , Falha de Equipamento , França , Humanos , Teste de Materiais , Preparo de Canal Radicular , Estresse Mecânico
14.
Shanghai Kou Qiang Yi Xue ; 29(2): 146-149, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-32626876

RESUMO

PURSPOSE: To compare the shaping ability and dental cracks of Twisted File and S3 in severely curved molar root canal preparation. METHODS: Sixty extracted mandibular molars with mesiobuccal canals (canal curvature angles beyond 25°) were selected and divided randomly into 2 groups with 30 canals in each group. The canals were scanned by cone-beam CT(CBCT) before and after root canal preparation .The canal transportation was recorded at 3 points (3, 5, 7 mm to root tip). After root canal preparation,all the roots were horizontally sectioned 3,5 and 7mm from the apex. The slices were observed under optical stereomicroscope. SPSS 19.0 software package was used for statistical analysis. RESULTS: Transportations occurred in all groups. No significant difference was found between the two groups of canal transportation at the two points (5 mm and 7 mm to root tip) (P>0.05); at the point of 3 mm to the root tip,the transportation of canals prepared by S3 was obviously lesser than the canals prepared by TF. There was no significant difference in the incidence of dentinal cracks between the two groups (P>0.05). CONCLUSIONS: Under the conditions of severely curved molar root canal in extracted teeth, cracks were found in both groups, S3 was found to be better in maintaining original canal shape than TF system.


Assuntos
Níquel , Preparo de Canal Radicular , Ligas Dentárias , Instrumentos Odontológicos , Cavidade Pulpar , Desenho de Equipamento , Dente Molar , Titânio
15.
J Contemp Dent Pract ; 21(5): 539-542, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32690836

RESUMO

AIM: The aim of the present study was to investigate the role of the flat design compared with a non-flat designed instrument on the centering ability in a simulated root canal system. MATERIALS AND METHODS: Two file systems were chosen: the F-One (Fanta Dental, Shanghai, China) and a prototype with the same design but without the flat-side design. A total of 50 simulated L-shaped root canals in resin blocks were shaped with a new instrument each. Pre- and postcanal preparation images were captured and superimposed to measure and compare the canal transportation and evaluate the centering ability of each file. The t test was performed and the level of significance was set at p < 0.05. RESULTS: Prototype files removed significantly less resin from the inner and the outer parts of the canal and showed significantly higher mean transportation values. CONCLUSION: It can be concluded that the F-One file system demonstrated better shaping ability compared with the prototype file system in L-shaped resin-simulated canals. CLINICAL RELEVANCE: The present study showed the safety of the flat-side design, minimizing the risk of iatrogenic errors such as ledging, perforation, or zipping of the root canal.


Assuntos
Níquel , Titânio , China , Ligas Dentárias , Instrumentos Odontológicos , Cavidade Pulpar , Desenho de Equipamento , Preparo de Canal Radicular
16.
J Contemp Dent Pract ; 21(4): 351-352, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32584267

RESUMO

In the last decades, the use of nickel-titanium (Ni-Ti) rotary instruments has become the most effective and popular method among endodontists for shaping root canals, even if there are still concerns regarding the increased risks of intracanal breakage or weakening of the instruments.1,2 So manufacturers started to modify the cross-sectional geometrical aspects of the files in order to improve their resistance to torsional and cyclic fatigue. Design is a major feature in determining instruments' properties including cutting efficiency, removal of debris, stresses generated during instrumentation, and the relative resistance to these stresses; however, a perfect design is not existing and any change in design is likely to provide some advantages but also some disadvantages.3,4.


Assuntos
Níquel , Titânio , Estudos Transversais , Ligas Dentárias , Instrumentos Odontológicos , Desenho de Equipamento , Falha de Equipamento , Preparo de Canal Radicular
17.
Shanghai Kou Qiang Yi Xue ; 29(1): 40-45, 2020 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-32524119

RESUMO

PURPOSE: To study the change of ion precipitation and surface roughness of three dental alloys'coexisting in standard electrolyte solution, in order to provide a reference for the selection of clinical alloy materials. METHODS: Standard samples of Ni-Cr alloy, Co-Cr alloy and Au-Ag-Pd alloy were prepared and divided into 5 groups: Ni-Cr alloy(group N), Co-Cr alloy(group C), Au-Ag-Pd alloy(Group A), Ni-Cr alloy contact with Au-Ag-Pd alloy(group NA), Ni-Cr alloy contact with Co-Cr alloy(group NC). All groups of alloys were soaked in standard electrolyte solution (T=37 ℃, pH=2.31) for 7 days. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the amount of ions released from each group. The surface morphology of each group was observed and the surface roughness(Ra) was measured using atomic force microscope(AFM). SPSS 18.0 software package was used for statistical analysis. RESULTS: The amount of nickel ions released from group N, NA, NC was (1.32±0.03) µg/cm2, (2.13±0.07) µg/cm2, (1.53±0.08) µg/cm2, respectively. Nickel ions of group NA and NC was significantly more than that of group N(P<0.05), nickel ions of group NA was significantly more than that of group NC(P<0.05). The amount of chromium ions released from group N, NA, NC was (0.06±0.01) µg/cm2, (0.08±0.01) µg/cm2, (0.05±0.01) µg/cm2, respectively, the amount of chromium ions of group NA was significantly more than that of group NC(P<0.05). The surface roughness of Ni-Cr alloy in group N, NA, NC was (4.60±0.16) nm, (5.37±0.08) nm, (5.04±0.15) nm, respectively. The surface roughness of Ni-Cr alloy in group NA and group NC was significantly larger than that in group N (P<0.05). When contact with Au-Ag-Pd alloy or Co-Cr alloy, the amount of nickel ions released and the surface roughness of Ni-Cr alloy both significantly increased. Compared with Co-Cr alloy, Au-Ag-Pd alloy caused Ni-Cr alloy to release more nickel, chromium ions and formed a rougher surface.


Assuntos
Ligas de Cromo , Ligas Dentárias , Íons , Teste de Materiais , Níquel , Propriedades de Superfície
18.
Am J Orthod Dentofacial Orthop ; 158(2): 199-208, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32576426

RESUMO

INTRODUCTION: This research aimed to evaluate the effect of titanium dioxide (TiO2) coating on surface roughness (Ra) of nickel-titanium (NiTi) archwires and its influence on Streptococcus mutans (S mutans) adhesion and enamel mineralization at the end of 1 month in orthodontic patients and to evaluate the integrity of the TiO2 coating. METHODS: Twelve patients undergoing orthodontic treatment with preadjusted edgewise appliance formed the sample for this prospective clinical study. Uncoated NiTi archwires and TiO2 nanoparticle coated NiTi archwires in as-received condition and after 1 month of intraoral use were subjected to Ra analysis using surface profilometry, and surface topography using scanning electron microscopy. S mutans adhesion was evaluated on the retrieved archwires using real-time polymerase chain reaction (PCR). Enamel mineral content in the arches related to the uncoated and coated archwires was evaluated using DIAGNOdent. RESULTS: After 1 month of intraoral use, both coated and uncoated archwires exhibited a rougher surface with coated archwires demonstrating greater quantum of increase (control, P = 0.002; experimental, P = 0.002). S mutans adhesion was more in uncoated archwires (P = 0.0005). The TiO2 nanoparticle coating on the NiTi archwires showed delamination, deterioration and was lost by 60% at the end of 1 month. Laser fluorescence values did not show any significant difference (control, P = 0.182; experimental, P = 0.105). CONCLUSIONS: TiO2 nanoparticle coating on NiTi archwires causes an initial reduction in roughness; however, at the end of 1 month, the benefit was lost. S mutans adhesion was lesser on the coated wires, which could be attributed to reduced initial Ra and antibacterial property of TiO2. Orthodontic archwire appears to have a limited role in enamel demineralization.


Assuntos
Streptococcus mutans , Ligas Dentárias , Esmalte Dentário , Humanos , Teste de Materiais , Níquel , Fios Ortodônticos , Estudos Prospectivos , Propriedades de Superfície , Titânio
20.
J Endod ; 46(8): 1125-1129, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32497655

RESUMO

INTRODUCTION: The aim of this study was to compare the buckling resistance of nickel-titanium (NiTi) instruments for glide path preparation depending on the test mode (static vs dynamic). METHODS: The conventional PathFile (PF; Dentsply Sirona, Ballaigues, Switzerland) and heat-treated ProGlider (PG, Dentsply Sirona) and WaveOne Gold Glider (WG, Dentsply Sirona) were evaluated. The instrument tips were placed in a small dimple prepared in an aluminum cube in a customized device. The file was then pushed in the axial direction at a 1.0-mm/s crosshead speed with rotation (dynamic mode) or without rotation (static mode). The dynamic mode of WG used its dedicated reciprocating rotation, whereas the others were rotated continuously at 300 rpm. The axial load and lateral buckling displacement were simultaneously measured. Data were analyzed statistically using 2-way analysis of variance (P = .05). RESULTS: The buckling resistance in the dynamic mode was higher than in the static mode for PG and WG (P < .05), whereas PF was not influenced by test modes (P > .05). In the dynamic mode, the PG required the highest buckling load followed by PF and WG (P < .05). In the static mode, the WG showed the lowest load (P < .05). The dynamic mode showed significantly more upper level lateral buckling displacement than in the static mode (P < .05). CONCLUSIONS: When the glide path preparation instruments moved in the dynamic mode as in clinical situations, the buckling resistance of the heat-treated NiTi glide path instruments was higher than in the static condition. The heat-treated instruments may have better buckling resistance than the conventional NiTi instrument in clinical situations.


Assuntos
Níquel , Titânio , Ligas Dentárias , Desenho de Equipamento , Teste de Materiais , Preparo de Canal Radicular , Rotação
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